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DISTRIBUTION OF ORGANISMS
Before understanding the details of distribution of VERTEBRATE ZOOLOGY vertebrates, let us understand distribution of living organisms. Usually the living organisms are INTRODUCTION classified as below along with some of chief characteristics. For your information virus do not fit nearly any classification of living organisms By because they have a very simple, noncellular Dr. K. S. Goudar structure and cannot exist independently of other organisms.
DISTRIBUTION OF ORGANISMS DISTRIBUTION OF ANIMALS
DISTRIBUTION OF INVERTEBRATES DISTRIBUTION OF VERTEBRATES
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CRITERIA CRITERIA
There are 3 types of body plan symmetry. Animals are grouped using a variety of criteria. Bilateral symmetry: Three criteria are used to categorize animals: Animals with bilateral symmetry can be divided 1. Body plan symmetry equally along only one 2. Tissue layers plane, which splits an 3. Developmental patterns animal into mirror-image sides.
CRITERIA CRITERIA Both radial and asymmetrical animal types have ectoderm (outer layer) and endoderm (inner layer) Radial symmetry: Body and they are called as diploblastic animlas. arranged in circle around a central axis (usually the Whereas bilateral animals have mesoderm (middle mouth). layer) also. Such animals are called as triploblastic animals Asymmetry: Body has no general plan or central axis. It is irregular in shape.
CRITERIA DISTRIBUTION OF VERTEBRATES Animals are divided into two major groups,
1. The Protostomes 2. The Deuterostomes.
Protostomes form mouth first, and anus second.
Deuterostomes first form the anus and then the mouth.
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WHAT IS VERTEBRATE WHAT IS VERTEBRATE The vertebrates and Protochordates together from Vertebrate (subphylum Vertebrata) is an animal of the second big group of animals besides the a large group distinguished by the possession of a Invertebrata. vertebrates are the largest of the backbone or spinal column, including mammals, deuterostome birds, reptiles, amphibians, and fishes.
GEOLOGIC TIME SCALE TIME SCALE
Anno Domini = In the year of lord
HUMAN TIME SCALE GEOLOGIC TIME SCALE
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GEOLOGIC TIME SCALE GEOLOGIC TIME SCALE
The Geologic Time Scale is the history of the Earth broken down into spans of time marked by various events. There are other markers, like the types of species and how they evolved, that distinguish one time from another on the Geologic Time Scale.
GEOLOGIC TIME SCALE GEOLOGIC TIME SCALE DIVISIONS
There are four main time spans the generally mark the Geologic Time Scale divisions. The first, Precambrian Time, is not an actual era on the Geologic Time Scale because the lack of diversity of life, but the other three divisions are defined eras. The Paleozoic Era, Mesozoic Era, and Cenozoic Era saw many great changes.
PRECAMBRIAN TIME PRECAMBRIAN TIME (4.6 billion years ago - 540 million years ago) (4.6 billion years ago - 540 million years ago)
The Precambrian Time Span began at the It wasn't until the end beginning of the Earth of this time period that 4.6 billion years ago. For single celled organisms billions of years there came into existence. was no life on Earth.
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PRECAMBRIAN TIME PRECAMBRIAN TIME (4.6 billion years ago - 540 million years ago) (4.6 billion years ago - 542 million years ago)
No one knows for sure The end of this time span saw the rise of a few how life on Earth began, more complex animals in the oceans like jellyfish. but there are several There was still no life on land and the atmosphere theories like the was just beginning to accumulate the oxygen Primoridal Soup Theory, needed for higher order animals to survive. It Hydrothermal Vent wasn't until the next era that life really began to Theory, and Panspermia take off and diversify. Theory.
GEOLOGIC TIME SCALE PALEOZOIC ERA (540 million years ago - 250 million years ago)
The Paleozoic Era began with the Cambrian Explosion. This relatively rapid period of large amounts of speciation kicked off a long time span of flourishing life on earth.
PALEOZOIC ERA PALEOZOIC ERA (540 million years ago - 250 million years ago) (540 million years ago - 250 million years ago) The end of the Paleozoic This great amounts of Era came with the life in the oceans soon largest mass extinction moved onto land. First in the history of life on plants made the move Earth. The Permian and then invertebrates. Extinction due to Not long after that, glaciations (covered vertebrates moved to with ice sheets) wiped land as well. Many new out about 95% of species appeared and marine life and nearly thrived. 70% of life on land.
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GEOLOGIC TIME SCALE PALEOZOIC ERA (540 million years ago - 250 million years ago) Climate changes were most likely the cause of this extinction as the continents all drifted together to form Pangaea. The mass extinction paved the way for new species to arise and a new era to begin.
MESOZOIC ERA MESOZOIC ERA (250 million years ago - 65 million years ago) (250 million years ago - 65 million years ago) The Mesozoic Era is the next era on the Geologic The Mesozoic Era is also known as the "age of the Time Scale. After the Permian Extinction caused so dinosaurs" because dinosaurs were the dominant many species to go extinct, many new species species for much of the era. Dinosaurs started off evolved and thrived. small and got larger as the Mesozoic Era went on.
MESOZOIC ERA MESOZOIC ERA (250 million years ago - 65 million years ago) (250 million years ago - 65 million years ago)
The climate during the Mesozoic Era was very humid and tropical and many lush (growing Another mass extinction marks the end of the extreme in abundance), green plants were found Mesozoic Era. All dinosaurs, and many other all over the Earth. Herbivores especially thrived animals, especially herbivores, completely died off. during this time period. Besides dinosaurs, small Again, niches were needing to be filled by new mammals came into existence. Birds also evolved species in the next era. from the dinosaurs during the Mesozoic Era.
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GEOLOGIC TIME SCALE CENOZOIC ERA (65 million years ago - Present)
The last and current time period on the Geologic Time Scale is the Cenozoic Period.
CENOZOIC ERA CENOZOIC ERA (65 million years ago - Present) (65 million years ago - Present) With large dinosaurs now extinct, the smaller mammals that survived were able to grow and become dominant life on Earth. Human evolution The climate has changed drastically over the also all happened during the Cenozoic Era. relatively short amount of time in this period. It got much cooler and drier than the Mesozoic Era climate. There was an ice age where most temperate parts of the Earth was covered in glaciers. This made life have to adapt rather rapidly and increased the rate of evolution.
CENOZOIC ERA EVOLUTION OF VERTEBRATES (65 million years ago - Present)
Vertebrate animals have come a long way since their tiny, translucent ancestors way back 500 All life on Earth evolved into their present day million years ago. Here's a brief chronological list forms. The Cenozoic Era has not ended and most of the major vertebrate animal groups, ranging likely will not end until another mass extinction from fish to amphibians to mammals, with some period. notable extinct reptile lineages (including archosaurs (Crocodile like), dinosaurs and pterosaurs (Flying Reptiles) in between.
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EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES FISH AND SHARKS FISH AND SHARKS These ocean dwellers Between 500 and 400 established the template million years ago, life on for later vertebrate earth was dominated by evolution. The first prehistoric fish. With prehistoric sharks their bilaterally evolved from their fish symmetric body plans, V- forebears about 420 shaped muscles and million years ago, and protected nerve chords quickly swam to the apex running down the of the undersea food lengths of their bodies. chain.
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES TETRAPODS TETRAPODS The proverbial "fish out Crucially, the first of water," tetrapodes tetrapodes descended were the first from lobe-finned, rather vertebrates to climb out than ray-finned, fish, of the sea and colonize which possessed the least swampy land, a key characteristic skeletal evolutionary transition structure that morphed that occurred into the fingers, claws somewhere between and paws of later 400 and 350 million vertebrates. years ago.
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES AMPHIBIANS AMPHIBIANS
Often considered a mere During the Carboniferous way station between period--from about 360 earlier tetrapodes and to 300 million years ago- later reptiles, -terrestrial life on earth amphibians were was dominated by crucially important in prehistoric amphibians. their own right.
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EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES AMPHIBIANS AMPHIBIANS
Since they were the first vertebrates to figure out Today, amphibians are a way to colonize dry represented by frogs, land (however, these toads and salamanders, creatures still needed to and their population is lay their eggs in water, rapidly dwindling under which severely limited environmental stress. their mobility).
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES TERRESTRIAL REPTILES TERRESTRIAL REPTILES
The earth's land masses were quickly populated by About 320 million years the first true reptiles pelycosaurs (the primitive evolved from amphibians (with their scaly skin and reptiles that preceded the semi-permeable eggs, reptiles were free to leave dinosaurs.), archosaurs bodies of water behind and venture deep into dry (including prehistoric land). crocodiles), anapsids (including prehistoric turtles).
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES TERRESTRIAL REPTILES TERRESTRIAL REPTILES
Later on two-legged Then prehistoric snakes, archosaurs spawned the and therapsids (the first dinosaurs, the "mammal-like reptiles" that descendants of which later evolved into the first ruled the planet until mammals) came into the end of the Mesozoic existence. Era 175 million years later.
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EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES MARINE REPTILES MARINE REPTILES The ichthyosaurs At least some of the first overlapped with, and reptiles led partly (or were then succeeded by, mostly) aquatic lifestyles, long-necked plesiosaurs but the true age of and muscular pliosaurs, marine reptiles didn't which themselves begin until the overlapped with, and appearance of the were then succeeded by, ichthyosaurs ("fish the exceptionally sleek, lizards“). vicious mosasaurs.
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES MARINE REPTILES AVIAN REPTILES
Often mistakenly All of these marine referred to as dinosaurs, reptiles went extinct 65 pterosaurs ("winged million years ago along lizards") were actually a with their terrestrial distinct family of reptiles dinosaur cousins. that evolved from archosaurs.
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES AVIAN REPTILES BIRDS It's difficult to pin down the exact moment when the first true prehistoric birds The pterosaurs of the evolved from their dinosaur early Mesozoic Era were forebears; most fairly small, but some palaeontologists point to truly gigantic breeds the late Jurassic period, (such as the 200-pound about 150 million years ago, Quetzalcoatlus). on the evidence of distinctly bird-like dinosaurs like Archaeopteryx.
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EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES BIRDS BIRDS By the way, following the classification system However, it's possible known as "cladistics,“ (a that birds evolved classification of animals multiple times during and plants into groups the Mesozoic Era, most based on characteristics recently from the small, which originated in a feathered theropods common evolutionary (sometimes called "dino- ancestor) this refer to birds“). modern birds as dinosaurs!
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES MESOZOIC MAMMALS MESOZOIC MAMMALS All we know for sure is that small, furry, warm- As with most such evolutionary transitions, there blooded, mammal-like creatures skittered across wasn't a bright line separating the most advanced the high branches of trees about 230 million years therapsids ("mammal-like reptiles“). ago, and coexisted on unequal terms with dinosaurs.
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES MESOZOIC MAMMALS MEGAFAUNA MAMMALS Because they were so small and fragile, most After the dinosaurs and Mesozoic mammals are represented in the fossil marine reptiles vanished record only by their teeth, though some species off from the earth 65 left surprisingly complete skeletons. million years ago, the next big theme in vertebrate evolution was the rapid progression of mammals from small, timid, mouse-sized creatures to the giant megafauna.
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EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES MEGAFAUNA MAMMALS MEGAFAUNA MAMMALS The megafauna including oversized wombats (Burrowing plant-eating Among the mammals that ruled the planet in the Australian marsupial absence of dinosaurs and mosasaurs were which resembles a small prehistoric cats, prehistoric dogs, prehistoric bear with short legs), elephants, prehistoric horses and prehistoric rhinoceroses, camels and whales, most species of which went extinct often at beavers (a large semi the hands of early humans. aquatic broad-tailed rodent).
EVOLUTION OF VERTEBRATES EVOLUTION OF VERTEBRATES PRIMATES PRIMATES Technically, there's no good reason to separate The first primates appear in the fossil record into a prehistoric primates from the other mammalian bewildering (unknown origin) array of lemurs megafauna that succeeded the dinosaurs, but it's (arboreal primate with a pointed snout and natural to want to distinguish our human ancestors typically a long tail, found only in Madagascar), from the mainstream of vertebrate evolution. monkeys, apes and anthropoids (the direct ancestors of modern humans).
EVOLUTION OF VERTEBRATES PRIMATES Palaeontologists are still trying to sort out the evolutionary relationships of these fossil primates, as new "missing link" species are constantly being discovered. Thank You
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THE FOSSIL RECORD THE FOSSIL RECORD
How fossils are formed and Fossils are remains of discovered (fossilization)? organisms preserved in • Usually formed from sediments which in the sedimentary rocks course of time have become • When we think of fossil rocks vertebrates, we probably Direct evidences for picture bones and teeth, evolution are formed by the hard parts of a body using fossils that more readily resist • Fossils tell us past history the destructive processes of organisms following death and burial • Indirect evidences are • Certainly most fossil also used – based on the vertebrates are known living from their skeletons and dentition
THE FOSSIL RECORD THE FOSSIL RECORD
• The calcium phosphate • If a full animal skeleton is compound composing bones discovered, microscopic analysis of and teeth is a mineral usually the region occupied in life by the stomach might reveal the types of preserved indefinitely, with foods eaten shortly before its little change in structure or death composition • Dung is sometimes fossilized • • Although we might not know Occasionally products of which animal dropped it, we can vertebrates, such as eggs, will gain some notion about the types fossilize of foods eaten. • If tiny young bones are • Soft parts usually decay quickly after death and seldom fossilize. preserved inside, we can • Occasionally soft parts leave an identify them and the impression in the terrain in which they group to which they are buried • Impressions of feathers in the rock belong around the skeleton of Archaeopteryx • Infrequently, fossils preserve demonstrate thatthis animal was a bird more than just their hard • The past behavior of now extinct animals is sometimes implied by their parts fossilized skeletons
THE FOSSIL RECORD THE FOSSIL RECORD
1. Stratigraphy – Relative dating How fossils are dated? Dating of fossils • A method of placing fossils in a • To discover a fossil is not relative sequence to each other enough • Based on the sedimentary layers • Its position in time with - rocks could be arranged from regard to other species oldest (deepest) to youngest (surface) must be determined as • Similar strata, layered one on well, because this will help top of another, are built in to place its morphology in chronological order an evolutionary sequence • Each layer of rock is called a • Techniques for dating time horizon because it contains fossils vary, and preferably the remains of organisms from several are used to verify one slice in time – the d/t layers age: mark time intervals
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THE FOSSIL RECORD THE FOSSIL RECORD • Any fossils contained within separate layers can be ordered from the oldest to the most 2. Radiometric dating – the widely recent, bottom to top used absolute dating technique • Although this gives no absolute • Paleontologists use radiometric age, it does produce a chronological sequence of fossil dating to determine more species relative to each other precisely the age of fossils • By placing fossils in their • In this process, they study the stratigraphicsequence, we can isotopes of minerals in the rock determine which arose first and surrounding the fossil which later, relative to other fossils • Radioactive elements decay in the same overall rock exposure and converted into another Since the sedimentary layers change element through time their place due to flooding, volcanic The change takes place at constant activity, etc we can’t depend in one overall rock exposure rate • If we have matching and • Half life (decay constant) – the congruent (matching) sedimentary amount of time for half of a layers in d/t parts of the world, we radioactive elements to decay will have reliable information for (decompose) dating of fossils
THE FOSSIL RECORD THE FOSSIL RECORD It is formulated by scientists Common examples include “decay” of Limitations of fossil record uranium-235 to lead-207 (710 million • All animals (& animal parts) years) and potassium-40 to argon-40 could not be fossilized (1.3 billion years). • Mostly, only the hard parts • Knowing the rates at which the isotopes decay, and having could be fossilized determined how much of the • Most protochordates couldn’t isotope has decayed in the rock be fossilized since they are soft sample, paleontologists can bodied determine the age of the rock— • Sedimentary rock formation is and thus the age of the fossil episodic preserved in the rock • We can’t recognize the life cycle • When rocks form, these of an organism which live at one radioactive isotopes are often time in one local place incorporated • If we compare the ratios of • The rocks should be formed and product to original and if we know persistent the rate at which this • The sedimentary rocks which transformation occurs, then the contain this information (fossil) age of the rock and, hence, the should be exposed for the age of fossils it holds can be paleontologists calculated
GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE Notochord: There is a dorsal median supporting rod in the body called notochord. The phylum vertebrata is also called as This is replaced by the vertebral column in chordata is a very big phylum comprising the higher chordates. animals which have the following characteristics which distinguish them from the Invertebrates. The distinguishing characters of vertebrates are
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GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE This supporting chord may remain So the presence of a median supporting cartilaginous throughout life. In some cases notochord at least, during some stage in the the notochord develops but disappears later. life history of any animal is an essential characteristic of a chordate.
GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE The invertebrates usually have a ventral Dorsal tubular nervous system: The central nerve cord and it is solid. Here also the nervous system, namely the brain and spinal presence of dorsal tubular nervous system cord are place dorsally above the nototchord may get obliterated (destroy) in later stages and they are hollow ie., contain cavities. of life.
GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE But evidence of its presence at least in Pharyngeal gill slits: All chordates have embryonic stages is also a chordate paired gill slits in the region of the pharynx. character.
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GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE
The gill slits may disappear later but at least in the embryonic Ventral heart: Where as the heart is usually stages pharyngeal gill dorsally placed in the invertebrates, the slits are present in all chordates have a ventral heart placed a little chordates (In man the below and behind the pharynx eustachian tubes are remnants of the gill slits in the embryo)
GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE
Post anal tail: All chordates possess a tail with the vertebral column extending into it. Hemoglobin in the corpuscles: The respiratory pigment, the iron containing hemoglobin is present in the erythrocytes (red blood corpuscles) while in the invertebrates the pigment is dissolved in the plasma
GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE The tail may be concealed internally as in man or may Number of limbs: No become lost as in the chordates has more adult frog. But its than two pairs of presence, extending limbs (a pair of beyond the anus at forelimbs and a pair least during some part of hind limbs). of the life is a chordate character.
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GENERAL CHARACTERS OF VERTEBRATE GENERAL CHARACTERS OF VERTEBRATE The limb may be absent as in the case of snakes but it is a secondary adaptation (Invertebrates can have more limbs) Hepatic portal system: In all chordates, blood from the alimentary canal is taken to the liver.
GENERAL CHARACTERS OF VERTEBRATE SALIENT FEATURES OF CHORDATES This system begins in 1. Body plan: bilateral symmetry a bed of capillaries in 2. They have three axis in their body the alimentary canal a. Anterio-posterior axis and ends in a bed of b. Dorso-ventral axis capillaries in the liver c. Lateral axis constituting the hepatic portal system. From the liver blood is later transported to the heart
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES Chordates have d/t body parts Trunk: d/t cavities are found and structures: Head Pharyngeal region here Trunk Tail 1. Abdominal cavity: Appendages Muscles accommodates the Skeleton viscera Head: Urochordates are mostly 2. Pericardial cavity: sessile; they don’t have well encloses heart (ventral) organized head 3. Pleural cavity: encloses As you go higher the head lung (cephalization) is well developed At the end of the trunk, there is Pharyngeal region is persistent in an opening (anus) for waste; aquatic chordates & in terrestrial but for invertebrates at the chordates replaced by neck extreme end
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SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
• Birds have reduced tail Tail: differ in function in d/t that can accommodate chordates feather • All (most) embryos of • Adult mammals have tail chordates have tail; some but diminished in lack tail in adults function • Adult fishes have a • Tail is lost in apes and prominent tail humans (but, there is a • Some adult amphibians sign of tail in adults as a possess tail tail bone (coccyx) – loss • Found in most adult of tail is a secondary reptiles phenomena
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
Appendages: are found as fins (in aquatic chordates) or limbs (in terrestrial chordates) 1. Fins – used generally for swimming; keeping balance, 2. Limbs - Based on changing direction & hypothesis supported by controlling the motion of evidence forward movement • Fore limbs – evolved • Median fins – earlier structure from pectoral fin i. Dorsal fins ii. Anal fins and • Hind limbs – evolved iii. Caudal fins • Paired fins – advanced from pelvic fin structure i. Pectoral fins and ii. Pelvic fins
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
There are 3 types of muscles: Muscles: muscle is a tissue; 1. Striated (skeletal) muscles – • There are d/t types of voluntary tissues in the body of Composed of long, cylindrical chordates & multinucleate muscle fiber • 1/3rd to ½ of the body of 1. Non-striated (smooth) chordates is made up of muscles – involuntary muscles muscles • Contractility is the major Uninucleate; lack cross characteristics of muscles striations • Used for movement of the 1. Cardiac muscles – involuntary whole body or part of it muscles • Several ways for classifying Heart muscles; unique striated muscles (but, muscles uninucleate cells)
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SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
Skeleton – body support (its main function) • Bone, scales and teeth constitute • The main composition of the skeletal important storage places for calcium material of chordates is calcium and other mineral salts phosphate; no bone in invertebrates • Can be grouped into two: regional • The hard parts of chordates can be components grouped into four: a. Axial skeleton – found along the • Bone, cartilage, dentine and enamel – all longitudinal axis of skeleton arose from the same ancestral structure Skull, vertebral column, ribs and • Bone: composed of collagenous fibers sternum (proteinaceous fiber on which the
b. Appendicular skeleton – found in the Ca3(PO4)2 deposited) and high appendages concentration of crystals of Ca3(PO4)2 • Pectoral and pelvic girdles, skeleton of • Cementing elements are water + paired fins and limbs and skeletons of mucopolysaccharide (to bind the crystals median fins to the collagenous matrix) • Most chordates have endoskeleton but • Cartilage: composed of collagenous fibers
exoskeleton for most invertebrates and low concentrations of Ca3(PO4)2 • But, some chordates have exoskeleton; • Cementing materials – sulphated e.g. Spines of Armadillos and shells of mucopolysaccharide tortoises
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
Esophagus is a muscular tube that Digestive system takes food from the pharynx to the • There are 2 openings in the digestive stomach. Peristalsis of the esophagus system of chordates without propels food in one direction and exception ensures that food gets to the • One for entry of food & another for exit of waste stomach even if the body is • Mouth → Pharynx → Esophagus → horizontal or upside down; Absent in Stomach → Intes ne → Anal opening lower chordates • Mouth is used for the entry of food and water Stomach - Although part of the • Pharynx is a muscular tube located in alimentary tube, the stomach is not a the neck, lined with mucous tube, but rather a sac that extends membrane, that connects the nose from the esophagus to the small and mouth with the trachea intestine. Absent in some chordates (windpipe) and esophagus and serves as a passageway for both air and food e.g. Lamprey – the only parasitic vertebrates
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
Intestine – in almost all aquatic chordates large Circulation and the heart intestine is absent b/c its role is for reabsorbtion of • The position of the heart is water; water is not a problem in aquatic habitat. ventral in chordates but dorsal in invertebrates • Blood flows dorsally backward Anal opening – For digestive and excretory (urinary) and ventrally forward wastes. But, in higher chordates the excretory & • Blood flows dorsally forward digestive wastes exit in d/t openings. and ventrally backward • In both cases, blood flows first Cloaca - Digestive & excretory wastes and towards the head region reproductive cells are released out through the same • Circulation of blood in opening in fishes, amphibians, reptiles and birds chordates is closed
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SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES Excretion • All the other chordates (vertebrates) have d/t types of • The process by which the body of animals removes kidney for excretion; differ in the development of nitrogenous wastes ducts and compactness • Ammonia, which requires a large amount of water for a. Archinephros removal, is the major nitrogenous waste in aquatic Kidney found in embryo of hagfish; this is the inferred ancestral environment condition of the vertebrate kidney • Urea & uric acid, which require relatively less amount of b. Pronephros water for removal, are the nitrogenous wastes in Functional kidney in adult hagfish and embryonic fishes and terrestrial habitat amphibians fleeting existence in embryonic reptiles, birds, and mammals • Salts and sometimes pigments are also removed c. Mesonephros together Functional kidney of adult lampreys, fishes, and amphibians; • Hemichordates and urochordates have specialized cell transient function in embryonic reptiles, birds, and mammals (nephrocytes) for excretion d. Meta nephros • Cephalochordates have nephridia for excretion Functional kidney of adult reptiles, birds, and mammals
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES Reproductive pattern in Reproduction vertebrates: • Sexual reproduction is the major form Oviparity • regeneration of bodies is seen in some lower • Egg laying pattern chordates • A few or mostly • Hermaphroditism is seen in some chordates such as thousands/millions of eggs urochordates and bony fishes may be produced • When the two gametes mature at the same time, self • In lamprey, fertilization & incubation are external fertilization is possible; but mostly the gonad produce • Fishes are largely oviparous; either a male or female gamete (protandry or mostly fertilization and protogyny) incubation are external • Parthenogenesis is seen in some chordates such as • In birds and reptiles desert lizards fertilization is internal and incubation is external
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES Ovoviviparity Viviparity • Fertilization is internal and • Giving young which are unnourished young is come already nourished; e.g. by out; it develops within the placenta in mammals body of the female, but • It is advantageous without placental i. Protection: gives protection attachment for embryo and young • The nourishment is stored ii. Conserve energy: for laying in the egg for most large number of eggs, to • The embryo receives migrate longer distances for maternal protection & laying eggs and for nest building oxygen iii. Assures fertilization: highly probable • E.g. in some fishes, some iv. Survival and dispersal are amphibians, some lizards, assured in viviparity kangaroo
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SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES Sexes are distinguished • Sexual dimorphism – Endocrine system differences in the morphology of the two • Pituitary, adrenal, thyroid, ovaries & testes, sexes; mostly males are parathyroid and islets of langerhans are found in all larger than females chordates • Sexual dichromatism – • The difference b/n lower and higher chordates is in difference in colour the organization of these glands indicates d/t sexes; in • Distinct in higher chordates but diffused in lower birds and fishes males chordates are usually brightly • Nervous system and endocrine system are highly coloured but females are related systems – the activity of one affects the other dull in colour
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES An amnion
Extra-embryonic • Inner membrane membranes surrounding the embryo forming the amniotic • Found exclusively in cavity and containing terrestrial chordates amniotic fluid • Four extra-embryonic • Encloses the embryo in membranes are present a fluid-filled sac – inside the leathery shell protects the embryo from desiccation; also acts as a cushion for the embryo
SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
A chorion Body temperature – source 1. Ectotherms – poikilotherms or cold blooded • Outer membrane surrounding the embryo that assists in gas • Maintain their body temperature by absorbing heat from exchange and in forming blood the environment vessels • Can’t control their body temperature • Provides a special hard covering • E.g. Agnatha, Chondrichthyes, Osteichthyes, Amphibians that is permeable to respiratory and Reptiles gases (O2 and CO2) while being impermeable to water vapor. 2. Endotherms – homeotherms or warm blooded • Can maintain a constant body temperature despite changes An allantois in the temperature of the environment • Provides a sac to store • They depend on internal sources to warm up their body nitrogenous waste and • Exhibit structural and physiological adaptations to keep A yolk sac internal temperature constant • Enclosing the yolk • E.g. Birds and Mammals
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SALIENT FEATURES OF CHORDATES SALIENT FEATURES OF CHORDATES
Integument – skin/outer body surface The skin of vertebrates has two major layers: epidermis & dermis b. Cover of the skin a. Secretions • Naked – Agnatha, Amphibians i. Glandular vertebrates • Dermal scales – arises from the dermal layer; • Have glands on their skin to produce mucous & other secretions • Agnatha, chondrichthyes, osteichthyes and amphibians chondrichthyes, osteichthyes ii. Aglandular vertebrates • Epidermal scales – arises from the epidermal layer; • No glands (no secretions); dry skin reptiles • Reptiles and birds • Feathers and epidermal scales – birds iii. Secondarily glandular vertebrates – mammals • No glands in their ancestors but secondarily they developed it • Hair - mammals • There are sweat glands, sebaceous glands
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SALIENT FEATURES OF CHORDATES SUBPHYLUM HEMICHORDATA
Members of the hemichordates are marine “worms” with apparent links to chordates on the one hand and to Notochord echinoderms on the other Neural Tube They share with chordates unmistakable pharyngeal slits Pharyngeal Gill Slits In the collar region, the epidermis and Ventral Heart dorsal nerve cord are invaginated into a collar cord. Hemoglobin in the Corpuscles • They also have dorsal partially Post Anal Tail hollow nerve cord Hemichordates lack a true postanal tail Four Limbs They also lack a notochord Although in possession of pharyngeal Hepatic Portal System slits, overall hemichordates lack other homologous equivalents of other major chordate features, hence, the name hemi- or half-chordates The larvae stage is called as tornaria larva
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SUBPHYLUM HEMICHORDATA SUBPHYLUM HEMICHORDATA Tornaria larva resembles the auricularia Respiration is done by gills larva or Bipinnaria larvae of Excretion is accomplished by echinoderms nephrocytes Hemichordates, like both echinoderms • Excretory wastes removed from the and chordates, are deuterostomes blood by nephrocytes → proboscis • They exhibit the characteristic gland (“glomerulus”) → Proboscis deuterostome patterns of coelom → Proboscis pore → out embryonic cleavage and coelom The nervous system is primitive – similar formation with invertebrates (not comparable to Blood vascular system is closed vertebrates) • The non-contractile central sinus In the proboscis area around the serve as heart; contraction is done proboscis pore, they possess a structure by pericardium called stomochord • Direction of blood flow is the same • It arises in the embryo as an with invertebrates outpocketing from the roof of the • The blood is colourless – not embryonic gut anterior to the typical of white blood cells pharynx • No cells in their blood (sometimes • In the adult, it retains a narrow amoebocytes) connection to what becomes the • No capillaries; but dorsal vessel buccal cavity (veins) & ventral vessel (arteries)
SUBPHYLUM HEMICHORDATA SUBPHYLUM HEMICHORDATA CLASS ENTEROPNEUSTA
No major sense organs are available or Commonly knwn as "Acorn Worms” they are poorly developed They are marine animals of both deep • But there are neurosensory cells; and shallow waters Photoreceptors and Most live in mucus lined burrows and chemoreceptors have a body with three regions— Sexes are separate; no hermaphroditism proboscis, collar & trunk – each with • The sexes are indistinguishable its own coelom from outside; no sexual The proboscis, used in both locomotion dimorphism nor dichromatism and feeding • Gonads are found at the anterior Some species are suspension feeders, part of the trunk; Mostly extracting tiny bits of organic material fertilization is external and plankton directly from the water No sign of endocrine system In these forms, the synchronous beating Within the hemichordates are two of cilia on the outer surface of the taxonomic groups (classes), the proboscis sets up water currents that enteropneusts, burrowing forms, and flow across the animal’s mucous surface the pterobranchs, usually sessile forms
SUBPHYLUM HEMICHORDATA SUBPHYLUM HEMICHORDATA CLASS ENTEROPNEUSTA CLASS ENTEROPNEUSTA
In some species, development proceeds directly from egg to young adult In most, however, there is a tricoelomic tornaria larval stage in that the three • Suspension mucous feeding: Direction body cavities include an anterior and movement of food and mucus are protocoel, a middle mesocoel, and a indicated by arrows posterior metacoel, which become the • Food material, carried along in the coelom of the proboscis, collar, and water current generated by surface trunk, respectively cilia, travels across the proboscis The tornaria feeds and may remain a and into the mouth where it is planktonic larva for several months captured in mucus and swallowed before undergoing metamorphosis into • Rejected food material collects in a the benthic adult. band around the collar and is shed The adult body is covered by a ciliated epithelium with glandular cells that produce a mucous coating E.g. Balanoglossus
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SUBPHYLUM HEMICHORDATA SUBPHYLUM HEMICHORDATA CLASS PTEROBRANCHIA CLASS PTEROBRANCHIA
Most pterobranchs, of which there are only two genera, live in secreted tubes in oceanic waters These species are small and colonial and Notice that this pterobranchia is commonly referred to as a zooid • Proboscis,collar, and trunk are has the same body plan as an present in each zooid, although acorn worm—proboscis, they may be quite modified collar, trunk—but these three • The zooids within one colony are produced by asexual budding, so features are modified and the all are descended from a single whole animal lives in a tube larva and when disturbed, the stalk Stomochord is usually present The nervous system is even simpler than shortens to pull a pterobranch that of acorn worms to safety inside the tube. • A tubular nerve cord is absent E.g. Rhabdopleura
SUBPHYLUM UROCHORDATA SUBPHYLUM UROCHORDATA CLASS ASCIDIACEA At some point in their life histories, urochordates generally show all five Ascidiacea are sessile as adults, but shared derived chordate characteristics: have swimming larvae, notochord, pharyngeal slits, endostyle, The common name, tunicates, is tubular nerve cord, and postanal tail inspired by the characteristic flexible Urochordates are specialists at feeding outer body cover, the tunic on suspended matter, especially very • It is secreted by the underlying tiny particulate plankton epidermis which characterizes the In most, the pharynx is expanded into a urochordates complex straining apparatus, the Commonly known as “Sea Squirts” branchial basket Ascidians are marine animals that are In a few species the filtering apparatus often brightly colored is secreted by the epidermis and Some species are solitary, others surrounds the animal colonial All species are marine Adults are sessile, but larvae are Urochordate literally means “tail back planktonic. string,” a reference to the notochord. Urochordates are divided into three major taxonomic classes
SUBPHYLUM UROCHORDATA SUBPHYLUM UROCHORDATA CLASS ASCIDIACEA CLASS ASCIDIACEA
Larva: The larva, sometimes called the ascidian The “postanal” tail is present, although tadpole, sometimes twisted or rotated about 90° Only the larval stage exhibits all five to the body chordate characteristics simultaneously Beneath the tunic, the epidermis at the The small pharynx bears slits in the anterior end of the body forms adhesive tadpole of colonial species papillae that serve to attach the larva to The tubular nerve cord extends into a a substrate at the end of its planktonic tail supported internally by a turgid existence notochord The central nervous system forms In solitary ascidian species, the gut does dorsally in typical chordate fashion not fully differentiate in the nonfeeding It has three subdivisions: (1) sensory larva, so an anus is not present vesicle and (2) visceral ganglion, both of In many colonial species, however, the which form a rudimentary brain, and (3) gut may be fully differentiated, the dorsal, hollow nerve cord extending including an anus that opens into the into the tail atrial chamber, and feeding may begin within 30 minutes after settlement
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SUBPHYLUM UROCHORDATA SUBPHYLUM UROCHORDATA CLASS ASCIDIACEA CLASS ASCIDIACEA Metamorphosis : At the end of its short planktonic stage, the ascidian larva makes contact with the Adult substrate of choice, usually in a dark or shaded location, adhesive papillae take hold to The tunic, composed of a unique attach it, and metamorphosis to a young adult begins almost immediately protein, tunicin, and a polysaccharide Most of the chordate features that made their debut in the larva, namely, notochord, similar to plant cellulose, forms the tail,and dorsal nerve tube, disappear in the forming adult body wall of an ascidian adult The branchial basket, a large atrial cavity around this basket, and the viscera are enclosed within the walls formed by the tunic The tunic attaches the base of the animal to a secure substrate Incurrent (branchial) and excurrent (atrial) siphons form entrance and exit portals for the stream of water that circulates through the body of the tunicate
SUBPHYLUM UROCHORDATA SUBPHYLUM UROCHORDATA CLASS ASCIDIACEA CLASS ASCIDIACEA The sea squirt’s heart, located in the body near the pharynx, is tubular, with a single layer of muscle-like striated myoepithelial cells forming its wall Tiny, fingerlike sensory tentacles The surrounding pericardial cavity is the encircle the incurrent siphon to examine only remnant of the coelom the water entering and perhaps exclude Contraction of the heart pushes blood excessively large particles before water out to the organs and tunic. enters the branchial basket. After a few minutes, the flow reverses The complex pharyngeal slits, the to return blood along the same vessels stigmata, sieve the passing water before to the heart. it flows from the branchial basket into Unlike the vertebrate circulatory system, the atrium, the space between basket there is no continuity between the and tunic heart myoepitheliumand the blood From here, the current exits via the vessels. excurrent siphon. The blood contains a fluid plasma with Rows of cilia line the branchial basket many kinds of specialized cells, including amoebocytes that resemble vertebrate lymphocytes
SUBPHYLUM UROCHORDATA SUBPHYLUM UROCHORDATA CLASS ASCIDIACEA CLASS LARVACEA (APPENDICULARIA) Members of the worldwide class They are phagocytic, and some Larvacea are tiny marine animals that accumulate waste materials reach only a few millimeters in length No specialized excretory organ has been and reside within the planktonic found in tunicates community All ascidians are hermaphrodites; both Larvacea received their name because sexes occur in the same individual the adults retain larval characteristics (monoecious), although self-fertilization similar in some ways to the ascidian is rare. tadpole with its tail and trunk Solitary ascidians reproduce only The implication was that adult sexually, while colonial ascidians larvaceans derived from the larval stages reproduce sexually and asexually of ascidians Asexual reproduction involves budding In fact, more recent phylogenetic The rootlike stolons at the base of the analyses now suggest otherwise – body may fragment into pieces that larvaceans and ascidians are equally produce more individuals, or buds may ancient arise along blood vessels or viscera Because the larvacean lives within the E.g. Ascidia, gelatinous matrix it constructs, this matrix is termed a “house”
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SUBPHYLUM UROCHORDATA SUBPHYLUM CEPHALOCHORDATA CLASS LARVACEA (APPENDICULARIA) All species, except one, are monoecious, In 1836 William Yarrell recognized the special nature of these animals and named and most of these are protandrous; them Amphioxus (meaning pointed at both ends) (Not comparable) Amphioxus is a familiar common name with “lancelet” as another Maturation is so rapid that within 24 to Living cephalochordates occur worldwide in warm temperate and tropical seas 48 hours of fertilization They are built upon the characteristic chordate pattern that includes pharyngeal slits, Their rapid reproduction and special tubular dorsal nerve cord, notochord, and post anal tail or caudal fin feeding apparatus give larvaceans a They have two exit openings for waste materials competitive advantage over other i. Anus: for digestive waste ii. Atriopore: for discharge of excretory waste & aquatic suspension feeders reproductive gametes Larvaceans are especially adept at These animals are anatomically simple; suspension (ciliary) feeders on microorganisms gathering ultraplankton, very minute, and phytoplankton bacteria-sized organisms The trunk of the larvacean holds its major body organs The blood, which is mostly devoid of cells, circulates through a system of simple sinuses driven by the pumping action of a single heart The tail is thin and flat A tubular nerve cord is present
SUBPHYLUM CEPHALOCHORDATA SUBPHYLUM CEPHALOCHORDATA Excretion is accomplished by a pair of nephridia Microscopic food particles are captured on mucous sheets as water flows through gill • In Branchiostoma, the nephridia developes from the ectodermal cells and have no slits in the ciliated pharynx; the mucus is produced by endostyle relation with mesoderm. Oral hood → Pharynx → Mid gut → Hind gut → Anus • Thus, they are different from the kidney of vertebrates which are mesodermal in Show basic chordate features both in the larva and adult stages origin Circulation is closed within vessels • They closely resemble the protonephridia of flatworms or polychaete annelids, • The blood of amphioxus is colourless due to lack of any respiratory pigment thus providing a good example of parallel evolution Its main function seems to be the transportation of food and excretory products rather Nervous system is very much simplified, a well developed brain, as found in higher than 02 and C02 for gaseous exchange chordates is absent No blood cells • The central nervous system of Branchiostoma includes a hollow dorsal neural Special respiratory organs are lacking tube or nerve cord lying mid-dorsally just above the notochord – poor/no It is probable that most gaseous exchange occurs through superficial areas cephalization • It has no ganglia • The peripheral nervous system includes paired nerves arising from the nerve cord
SUBPHYLUM CEPHALOCHORDATA
Sexes are separate; but the male & female individuals look identical • The adult has 26 to 27 pairs of similar gonads • The mature sperm is one of the smallest among chordates, is about 18µm in length • The ovary contains ova which are large and somewhat rounded cells each 0.1mm in diameter and having a large nucleus VIDEO • Gonoducts are absent • Fertilization and development take place externally in sea water • The cephalochordate larval stage is planktonic, lasting from 75 to over 200 days
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SUBPHYLUM CEPHALOCHORDATA ORIGIN OF CHORDATES - THEORIES
Some primitive feature • Ciliary feeding; no heart; no respiratory pigments • No cephalization; jaws are absent • The absence of paired fins It is believed that Chordates have originated • Gonads do not have ducts Some advanced features from invertebrates. It is difficult to determine • Exhibit full chordate features • The presence of separate openings from which invertebrate group the chordates • The presence of median fins were developed. Chordate ancestors were soft bodied animals. Hence they were not preserved as Fossils.
ORIGIN OF CHORDATES - THEORIES COELENTERATE THEORY
According to this theory chordates were Many biology theories were put forward to developed from coelenterates. Radial explain the Origin of Chordates. symmetry coelenteron, cnidoblasts etc, were 1st and advanced characters were developed 1. Coelenterate theory to give rise to chordates. This theory infers 2. Annelid theory that chordates might have acquired higher 3. Echinoderm -Hemichordate theory characters independently. It is not correct and hence this theory is not acceptable.
ANNELID THEORY ANNELID THEORY
But the mouth would be dorsal which is This theory suggests that the chordates have unlike that of chordates. Metamerism and evolved from an annelid stock. The annelids appendages of annelids differ in nature from show bilateral symmetry, head, lateral those of the chordates. Bilateral symmetry, Coelome, complete digestive tract, closed head and complete digestive tract occur in circulatory system, hemoglobin, etc., like other non-chordate phyla also. Coelome is chordates. The resemblance is enhanced if, schizocoelic in annelids and enterocoelic in an annelid is turned upside down. lower chordates
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ANNELID THEORY ECHINODERM -HEMICHORDATE THEORY Haemoglobin is dissolved in the plasma in annelids but it is present in the red blood This theory infers origin of chordates, corpuscles in chordates. Annelid nerve cord hemichordates and echinoderms from a is double, and, ventral in contrast to single, common ancestor. This theory is based on hollow, dorsal nerve cord of chordates. Some the following evidences. striking differences exist between the annelids and the chordates in their 1. Embryological evidence embryology. Hence it is difficult to accept 2. Serogical evidence this theory.
EMBRYOLOGICAL EVIDENCE SEROGICAL EVIDENCE
Both echinoderms and chordates have enterocoelic coelome. There is resemblance A close similarity exists between the proteins between the bipinnaria larva of certain of the body-fluid of chordates and echinoderms and the tonaria larva of echinoderms. Hence the chordates are more hemichordates. In echinoderms chordates related to echinoderms. the central nervous system develops from a dorsal strip of ectoderm.
ECHINODERM -HEMICHORDATE THEORY
The radial symmetry of adult echinoderms will disprove their relationship with the bilaterally symmetrical chordates. In Thank You echinoderms radial symmetry is secondarily developed from a basically bilateral symmetry. Both the primitive and the early echinoderm larvae show bilateral symmetry.
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VERTEBRATE Vertebrates belong to the subphylum Vertebrata of VERTEBRATE ZOOLOGY the phylum Chordata Their names is derived from the presence of THE VERTEBRATES serially arranged 'Vertebrae‘ (L., vertebratus, jointed), which comprise a By major part of their axial Dr. K. S. Goudar endoskeleton, the vertebral column or the backbone
VERTEBRATE VERTEBRATE Another feature, that all A vertebrate may be vertebrates share as a defined as a special kind of common diagnostic chordate animal that has a character, is the cartilaginous or bony elaboration of anterior endoskeleton consisting of skeletal elements into a a cranium, housing a brain 'cranium' or skull' which and a vertebral column houses various sense through which the nerve organs and a complex cord passes brain Vertebrates occupy This gives another name, marine, freshwater, the ‘Craniata’, which is terrestrial, and aerial sometimes used for the environments, and exhibit group a vast array of lifestyles
VERTEBRATE VERTEBRATE Like tunicates and amphioxus, vertebrates are proper The vertebral column chordates and possess at some (spinal column or time during their lives all five backbone) is made of defining chordate individual bones called characteristics: notochord, vertebrae pharyngeal slits, tubular and dorsal nerve tube, and postanal The names of vertebrae indicate their location tail along the length of the Their success may be due to spinal column their great variety of • There are cervical, innovations as well thoracic, lumbar, sacral, Two of these innovations—the and caudal vertebrae vertebral column and the • The cervical vertebrae are cranium—provide names for those within the neck this major taxon.
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VERTEBRATE VERTEBRATE All of the vertebrae • The thoracic vertebrae articulate with one articulate (form joints) another in sequence, with the ribs on the posterior side of the connected by ligaments, to trunk. form a flexible backbone • The lumbar vertebrae, that supports the trunk the largest and strongest bones of the spine, are and head found in the small of the They also form the back vertebral canal, a • The sacral vertebrae permits the articulation of continuous tunnel within the two hip bones: the the bones that contains sacroiliac joints the spinal cord and • The caudal vertebrae is protects it from the tail vertebrae mechanical injury
VERTEBRATE The supporting part of a vertebra is its body; the bodies of adjacent vertebrae are separated by discs of fibrous cartilage These discs cushion and absorb shock and permit some movement between vertebrae (symphysis joints) Most living forms of vertebrates also possess paired appendages and limb girdles The subphylum vertebrata is divided into different classes:
TYPES OF FINS TYPES OF FINS Diphycercal: Having or designating a tail fin in Heterocercal: A tail fin in which the vertebral which the upper lobe is column extends to the tip, larger than the lower and with symmetrical upper the vertebral column and lower parts, as in the extends into the upper lungfishes. lobe, as in sharks. Homocercal: Characterized Hypocercal: A tail in which by a tail fin having two the lower lobe is more symmetrical lobes pronounced or larger than extending from the end of the upper lobe. the vertebral column, as in most bony fishes.
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VERTEBRATE - AGNATHA VERTEBRATE - AGNATHA The first vertebrate animals b. Order Anaspida Jawless vertebrates • Head naked or covered Divided into 2 subclasses by a complex of small i. Subclass Monorhina plates; Arrangement of scales was complicated; Possess a single, large, Possess hypocercal tail median nostril on top of head b/n eyes c. Order Cyclostomata • Possess cyclic mouth Divided into 3 orders a. Order Osteostraci • Further divided into 2 suborders • Had bony shells • Myxinoidea (Hagfishes) • Possess heterocercal tail and Pteromyzontia (caudal fin) (Lampreys)
VERTEBRATE - AGNATHA VERTEBRATE - AGNATHA ii. Subclass Diplorhina All the extinct groups are collectively known as Two separate nasal openings, ostracoderms (Shell Divided into 2 orders skinned) a. Order Heterostraci • The earliest known • Body was large; Head was vertebrates were jawless encased in a shield primitive fishlike animals • Possess hypocercal tail collectively known as the b. Order Coelolepida ostracoderms • Their lateral eyes were • They resembled the widely apart present day cyclostomes, • Their tail was hypocercal together constitute or heterocercal jawless vertebrates, the Agnatha
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HAGFISHES Hagfishes are an entirely marine group (deep sea form), mud-burrowing, scavengers that feeds on annelids, molluscs, crustaceans, and dead or dying fishes Thus they are not parasitic like lampreys but are scavengers and predators. There are about 70 species of hagfishes, of which the best known in North America are the Atlantic hagfish, and the Pacific hagfish,
HAGFISHES Although almost completely blind, hagfishes are quickly attracted to food, especially dead or dying fishes, by their keenly developed senses of smell and touch VIDEO A hagfish enters a dead or dying animal through an orifice or by digging into the body Using two toothed, keratinized plates on its tongue that fold together in a pincer like action, the hagfish rasps bits of flesh from its prey 189
HAGFISHES HAGFISHES For extra leverage, the hagfish If disturbed or roughly often ties a knot in its tail, then handled, a hagfish exudes a passes the knot forward along milky fluid from special glands its body until it is pressed positioned along its body securely against the side of its On contact with seawater, the prey fluid forms a slime so slippery . Hagfishes can knot their bodies that the animal is almost to escape capture or give them impossible to grasp force to tear off food Unlike any other vertebrate, Hagfishes possess a single, the body fluids of hagfishes wide nostril placed terminally, are in osmotic equilibrium at the anterior end of the head with seawater, as are most Hagfishes are renowned for marine invertebrates their ability to generate . Body fluid of hagfishes is also enormous quantities of slime unique
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HAGFISHES HAGFISHES
. In other vertebrates, seawater is . In having high salt roughly two-thirds saltier than concentrations, hagfishes are body fluid physiologically like marine . Water moves osmotically out of invertebrates their body along this gradient so that marine vertebrates must Hagfishes have several other regulate their salt and water anatomical and physiological levels constantly to stay in peculiarities, including a low- balance with the surrounding pressure circulatory system environment served by three accessory . By contrast, the salt hearts in addition to the main concentrations in hagfish tissues are similar to surrounding heart positioned behind the seawater, there is no net flow of gills water in or out of the hagfish body.
HAGFISHES LAMPREYS Paired fins are absent . Two unequal median dorsal fins, Ovaries and testes occur in the first and second, are located near same individual, but only one the posterior end is functional; so hagfishes are . Around the tail there is a caudal not practicing hermaphrodites. fin, the upper lobe of which is No larval stage has ever been continuous with the second dorsal fin found, so development from . In some lampreys, the female yolk-filled eggs is thought to possesses an anal fin, but in be direct; that is, without males, it is reduced to a metamorphosis copulatory papilla – sexual dimorphism On each lateral side of the head is a large prominent eye . The two eyes lack eyelids and are covered by a transparent area of skin
LAMPREYS LAMPREYS
Skin is soft smooth, slimy and consists of many layers of cells Musculature and locomotion . Epidermis has many unicellular . Locomotion is by means of mucous glands producing slime powerful short segmental muscles of trunk and tail . Dermis is composed of collagen arranged in E-shaped myotomes, and elastin fibers, similar to that of fishes . Star-shaped chromatophores are . Muscle fibers are striated able to migrate, changing the skin colour dark or pale Their skeleton contains no true . A layer of subcutaneous tissue bone but includes notochord contains blood vessels, fat and and cartilage connective tissue . It resembles the notochord of . Pigment cells are present in amphioxus both in structure & dermis. function
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LAMPREYS Digestive system and feeding: . Mouth → Pharyngeal region – digestive tube → Esophagus → Intestine → Cloaca . Possess “rasping teeth” for piercing the host or scraping flesh – parasitic/ predators VIDEO . Mouth can be closed or opened by the forward and backward piston-like movement of the tongue . Buccal cavity communicates behind with two tubes, a dorsal esophagus and a ventral respiratory pharynx . The latter is a blind pouch, which bears 7 internal gill slits on each side
LAMPREYS LAMPREYS
. A valve like structure, the velum, . Digestive glands are well prevents the passage of food into developed the respiratory tube • A pair of buccal or salivary . There is no distinct stomach glands opening below the . Their intestine is straight tongue secrete an . Anterior part of intestine is anticoagulant dilated, representing the stomach • A bilobed voluminous liver . Posteriorly, the esophagus opens surrounds the anterior part of by a valve into the straight the intestine intestine which terminates at the • A gall bladder and a bile duct cloaca although present in the larva, . Inside the intestine is a are absent in the adult longitudinal fold to increase • Zymogen cells, which are surface area for absorption of found in the anterior part of food – analogous to villi of intestine, secrete pancreatic higher vertebrates enzymes
LAMPREYS LAMPREYS Respiration is accomplished by gills which are usually 7 pairs Circulatory system: . A lymphatic system is also' present . The heart is located ventrally just behind the last gill pouch, . Blood contains both red blood enclosed in a thick-walled corpuscles with haemoglobin and pericardium supported by a white blood corpuscles cartilaginous plate • Red blood corpuscles are . The heart is “S” shaped nucleated and circular in outline • It is made up of four chambers – one sinus • But white blood corpuscles venosus, one auricle, one are similar to lymphocytes ventricle and one conus . Blood forming tissues are present arteriosus in the spiral valve, kidney & • Blood from various parts of spinal cord the body returns to a small . Well developed than sinus where it first goes into protochordates a thin-walled auricle and then into a thick-walled ventricle
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LAMPREYS LAMPREYS Nervous system and sense organs Excretory system (urogenital . More developed than system) protochordates . Kidneys are of the mesonephric . The brain of the adult lamprey is type very primitive • Tubules (nephrones) → • In forebrain two large Mesonephric duct → olfactory lobes are found – Urinogenital sinus → Papilla responsible for smell → Cloaca • Midbrain has a pair of large . Tubules are used to conserve salt optic lobes - responsible for . Each tubule partially encloses a sight specialized cluster of capillaries • Hindbrain includes a small known as glomerulus – removes transverse rudimentary excess water cerebellum and a fairly well- developed medulla oblongata - responsible for hearing & balance A: Amphioxus, B: Tunicate C: The lamprey
LAMPREYS LAMPREYS • Ten pairs of cranial nerves . Sympathetic nervous system is are present – cranial nerves poorly defined 1st seen in this group . All the nerve fibers of lampreys are . Spinal cord is flat and peculiar as non-myelinated, because of which, no blood vessel is present within rate of conduction of nerve impulses it. is very slow . There are 2 nerves roots which . Sense organs: arise from spinal cord: dorsal • They have single, dorsal & (sensory) and ventral (motor) median nostril • Do not join in lampreys • The two lateral eyes are primitive • In hagfishes, fishes & • There are taste buds in the amphibians meet outside the pharynx vertebral column • In salt water, lampreys can • In all amniotes meet inside produce electric fields to detect the vertebral column the prey • The dorsal and ventral roots • Integumentary photoreceptors of spinal nerves remain showing photosensitivity are also separate found in the integument of lampreys
LAMPREYS Endocrine system is more developed . Pituitary, thyroid and adrenal glands the 3 prominent glands in lampreys Reproductive system . Sexes are separate (dioecious) VIDEO • Some sort of sexual dimorphism Females have large anal fins and males have genital papillae . There is no genital duct . Mature eggs or sperm escape from gonad into coelom, pass through genital pores into the urinogenital sinus, and leave the body through the urinogenital opening into water
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LAMPREYS . In spring or early summer, lampreys become sexually mature and migrate into a neighbouring freshwater stream or river for breeding . When they reach fresh water habitat , with their buccal funnels, the males move pebbles VIDEO from a sandy bottom and form a nest in the form of a shallow rounded depression • Then initiate each other for copulation . When a female attaches to a stone in the nest, a male winds his tail around her and eggs and sperm are discharged
LAMPREYS DIFFERENCES BETWEEN HAGFISHES AND LAMPREY . More than one pair may spawn in the same nest Characters Lampreys Hagfishes . The adults die after spawning Habitat Marine as well as freshwater Exclusively marine, . Fertilization is external, taking burrowing in sand place in water . A large female sea lamprey lays Feeding Rasp away flesh and suck Primarily scavengers, up to 236,000 eggs out blood of host burrowing into dead or . The eggs hatch in about 3 weeks fishes. morbid fish for flesh into minute transparent larvae consumption called ammocoetes • At first, they are about 7 mm Breeding Anadromous, i.e., ascend Spawn on ocean floor in length and stay in the nest fresh water rivers and . When about 15 mm long, they streams for spawning quit the nest and burrow in mud and sand in quiet water. Knot tying Not found For feeding and defense activity body draws a knot and squeezes out
DIFFERENCES BETWEEN HAGFISHES AND LAMPREY DIFFERENCES BETWEEN HAGFISHES AND LAMPREY
Characters Lampreys Hagfishes Characters Lampreys Hagfishes
Skin Less slimy Exceedingly slimy Spinal nerve Dorsal and Ventral roots Roots united Nostril High on head Terminal roots separate Paired eyes Large and functional Degenerate, coveted by Semicircular Two Single thick skin canals Mouth Ventral Terminal Sexes Separate United Tongue Less developed with larger Strongly developed with Eggs Small, naked, without shell Large, enclosed in a horny teeth smaller teeth shell Salivary glands Present secreting an Absent Cleavage of Holoblastic Meroblastic anticoagulant embryo Kidneys Advanced mesonephros Pronephros anterior, mesonephros posterior Development Indirect with a larval stage Direct, without larva and (ammocoete) metamorphosis Brain Better developed Poorly developed arid metamorphosis Cranial nerves 10 pairs present 8 pairs present
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GNATHOSTOMES GNATHOSTOMES JAWED VERTEBRATES JAWED VERTEBRATES Perhaps the greatest of all Jaws permitted the capture and advances in vertebrate history ingestion of a much wider array was the development of jaws of food than was available to the and the consequent revolution jawless ostracoderms, and they in the mode of life of early also permitted the development fishes of predatory lifestyles The development of hinged Fish with jaws could selectively jaws from the most anterior capture more food and occupy pair of primitive pharyngeal more niches than ostracoderms arches was one of the most and, thus, were more likely to survive and leave offspring important events in vertebrate evolution They could venture into new habitats in search of food, Jaws arose from one of the breeding sites, and retreats anterior pair of gill arches.
GNATHOSTOMES ORIGIN OF PAIRED FINS JAWED VERTEBRATES A second major development in Jaws, which also could be used the evolution of vertebrates was for defensive purposes, could the evolution of paired have aided these primitive fish appendages in both intraspecific and As early fishes became more interspecific combat active, they would have Thus, hinged jaws made experienced instability while in possible a revolution in the motion method of feeding and hence Presumably, just such conditions in the entire mode of life of favored any body projection that early fishes resisted roll (rotation around the The term gnathostome body axis), pitch (tilting up or includes all of the jawed fishes down), or yaw (swinging from and the tetrapods side to side) and led to the evolution of the first paired fins (pectoral and pelvic)
ORIGIN OF PAIRED FINS SCALES OF FISHES In many vertebrates, the Pectoral fins, which project exoskeletal covering of body is laterally from the sides of the made of two types of scales: body, are used for balancing epidermal and dermal and turning, whereas pelvic Epidermal scales are cornified fins serve as stabilizers derivatives of the Malpighian The associated girdles layer of epidermis stabilized the fins, served as . They are well developed in sites for muscle attachment, terrestrial vertebrates such as and transmitted propulsive reptiles, birds and mammals forces to the body Dermal scales are mesenchymal in origin and The origin of paired fins has especially developed in the long been debated and even fishes. today remains unresolved. . They are small, thin, cornified, calcareous or bony plates which fit closely together or overlap
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SCALES OF FISHES TYPES OF SCALES 1. Cosmoid scales Scales vary in size and shape . These do not occur in living in different species fishes; Latimeria – an exception The body of all fishes except . These were characteristic of members of family Siluridae certain ostracoderms and and a few bottom dwellers is covered by scales placoderms, Exoskeleton in the form of . These consisted of 4 distinct plates and scales which consist layers : an outermost thin of three distinct layers enamel-like ganoine, thick . The innermost layer of Pulp, the dentine-like cosmine, spongy intermediate one is Dentine and outer layer is of Enamel bone and innermost compact bone
TYPES OF SCALES TYPES OF SCALES 2. Placoid scales . These are characteristic of 3. Ganoid scales elasmobranch fishes only . Thick, usually rhomboid or . Each placoid scale consists of diamond-shaped plates closely a backwardly directed spine fitted side by side, like tiles, arising from a rounded or providing a bony armour to the rhomboidal basal plate fish embedded in dermis . In some cases they may overlap . Spine is made of enamel-like and basal plate of dentine-like bony material . A pulp cavity inside spine opens through basal plate.
TYPES OF SCALES TYPES OF SCALES
4. Cycloid scales . Cycloid scales are thin flexible translucent plates, rather circular in outline, thicker in . They overlap each other, each the centre and marked with scale embedded in a small several concentric lines of pocket of dermis growth which can be used for determining the age of the fish . Cycloid scales are found in lung fishes, . They are composed of a thin upper layer of bone and a lower layer of fibrous connective tissue
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TYPES OF SCALES TYPES OF SCALES
5. Ctenoid scales . These are characteristic of . Intermediate types between modern higher teleosteans such cycloid and ctenoid scales also as perch, sunfish, etc occur . In form, structure and . Certain fishes, such as arrangement they are similar to flounders, may bear both cycloid scales types, ctenoid scales dorsally . They are more firmly attached and cycloid ventrally and their exposed free hind parts which are not overlapped, bear numerous small comblike teeth or spines
TYPES OF TEETH (DENTITION) TYPES OF TEETH (DENTITION)
a. Attachment of teeth on the jawbone b. Replacement of teeth i. Acrodont – Teeth are attached to the outer surface of the jawbone i. Polyphyodont – Series of loss of teeth e.g. most lizards, lungfishes . Ability to continually replace teeth throughout the animal’s ii. Pleurodont – Teeth are attached to the inner side of the jawbone lifetime e.g. Chondrichthyes, Teleosts, Lizards Amphibians . E.g. Fishes, amphibians, reptiles iii. Thecodont – Teeth are set into sockets in the jawbone e.g. Mammals ii. Diphyodont – Develop 2 sets/generations of teeth . 1st set (generation) – milk (deciduous) teeth and 2nd set (generation) – permanent (adult) teeth e.g. mammals iii. Monophyodont – having only one set of teeth without replacement during the animal’s lifetime e.g. Lungfishes, Tuatara
TYPES OF TEETH (DENTITION) PLACODERMS
Their body was covered by hard plate – the group name c. Shape and size (appearance) The first jawed vertebrates (gnathostomes) i. Homodont – Having teeth similar in shape & size e.g. Some 450 million years ago, as the ostracoderms were disappearing, a host of more efficient and jawed fishes appeared Teleosts, most amphibians, most reptiles Placodermi were earliest jawed vertebrates of fossil record ii. Heterodont – Having teeth which are different in size They probably lived both in fresh water as well as seas shape; differentiated for various functions e.g. mammals Some primitive agnathan ostracoderms were probably the ancestors iii. Edentates – Toothless vertebrates (if present, highly of placoderms reduced) . But their fossil record does not show any connecting link between the jawless and the jawed fishes e.g. birds, toads Most placoderms possess paired fins . In an aquatic environment, development of strong mobile fins was coincident with the evolution of jaws, for swimming faster There are 2 known orders/groups
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PLACODERMS PLACODERMS i. Order Arthrodiriformes . Earliest placoderms . Resembled ostracoderms in ii. Order Antiarchiformes appearance and habitat . Bottom-dwellers and mud- . Heavy bony armour shields of feeders in fresh water. head and trunk meeting in a . Pectoral fins long movable joint (Gr., arthros. joint). . Small armoured placoderms, mostly <1m . Powerful gaping jaws with sharp shearing blades . Violently predaceous. . Large in size, up to 9m
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VERTEBRATE ZOOLOGY
ADVANCED FISHES- CHONDRICHTHES AND OSTEICHTHYES
By Dr. K. S. Goudar
CLASS CHONDRICHTHYES CLASS CHONDRICHTHYES (CARTILAGINOUS FISHES) (CARTILAGINOUS FISHES)
General Characters . Endoskeleton entirely . Mostly marine and cartilaginous,- without true predators bones (Gr., chondros, . Body fusiform or spindle cartilage + ichthys, fish) shaped • Notochord is persistent; . Fins both median and but reduced paired, all supported by • Vertebrae complete and fin rays separate • Pelvic fins bear • Pectoral and pelvic claspers in male girdles present • Tail heterocercal . Mouth ventral. Jaws present . Skin tough containing • Teeth are modified minute placoid scales placoid scales and mucous glands
CLASS CHONDRICHTHYES CLASS CHONDRICHTHYES (CARTILAGINOUS FISHES) (CARTILAGINOUS FISHES) . Heart with sinus venosus, . Digestive system with J- atrium, ventricle, and conus shaped stomach arteriosus • Intestine with spiral . Both renal and hepatic portal valve systems present • Often with large oil- . Temperature variable filled liver for buoyancy (poikilothermous). . Respiration by means of five . Mesonephric kidney to seven pairs of gills • Blood isosmotic or leading to exposed gill slits slightly hyperosmotic to in elasmobranchs seawater • 4 pairs of gills covered • High concentrations of by an operculum in urea and trimethylamine chimaeras; No air oxide in blood Kidneys bladder and lungs. opisthonephric
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CLASS CHONDRICHTHYES CLASS CHONDRICHTHYES (CARTILAGINOUS FISHES) (CARTILAGINOUS FISHES) . Cloaca present. . Brain of two olfactory lobes, . Sexes are separate; Gonads two cerebral hemispheres, paired; Gonoducts; open into two optic lobes, cerebellum, cloaca; Fertilization internal. medulla oblongata • Oviparous or • 10 pairs of cranial nerves ovoviviparous or • Three pairs of viviparous semicircular canals; • Eggs large, yolky senses of smell, vibration • Development direct, reception (lateral-line without metamorphosis system), vision, and • Separate urogenital and electroreception well- anal openings in developed chimaeras • Olfactory sacs do not. open into pharynx.
CLASS CHONDRICHTHYES SHARK (CARTILAGINOUS FISHES) Classification 1. Subclass Elasmobranchii . Distributed in all parts of the . Placoid scales usually world (especially in tropical present seas and oceans) . Five to seven gill arches and • Although most sharks are by gill slits in separate clefts nature timid and cautious, along pharynx some of them are dangerous . Upper jaw not fused to to humans cranium. • There are numerous Divided into many orders authenticated cases of shark Order Pleuroacanthodii – Spiny attacks by great white sharks, sharks (reaching 6 m); mako sharks; Order Cladoselachii - Primitive tiger sharks; bull sharks; and sharks hammerhead sharks, Order Selachii – Living sharks Order Batoidea – Skate fishes
SHARK SHARK
. More shark casualties have . Dogfish is chosen for study been reported from tropical for several reasons: and temperate waters of the . Its skeleton is not bony but cartilaginous, so that it is easy Australian region than from to dissect any other . It is neither too big nor too . During World War II there small but of a suitable size for were several reports of mass dissection, shark attacks on victims of . It is not a popular article of diet ship sinking in tropical . Its not highly specialized and waters can represent a generalized . Dogfish sharks are fish extensively studied nearly all . Some of its anatomical over the world. features are found in the embryos of higher vertebrates.
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SHARK SHARK
Although to most people . The asymmetrical sharks have a sinister (evil) heterocercal tail, appearance and fearsome . There are paired pectoral reputation, they are at the and pelvic fins, one or same time among the most two median dorsal fins gracefully streamlined of all and a median caudal fin fishes . The paired fins are used . The body of a dogfish shark is for keeping balance & fusiform (spindle-shaped); movement divided into head, trunk and . A median anal fin is tail present in most sharks . Mouth is ventral and . In males, the medial part of crescentic in shape the pelvic fin is modified to . Possess polyphyodont and form a clasper, which is used homodont. Lower jaw shows new teeth development inside in copulation the jaw
SHARK SHARK Digestive System . The tough, leathery skin is . Sharks found at the top of the covered with toothlike, dermal pyramid; can eat all vertebrates placoid scales arranged to but not eaten by any vertebrates reduce the turbulence of water . The digestive system includes . Have no air/gas/swim bladder, the alimentary canal or gut but possess large liver through which the food passes (accounts 25% of the body) and the glands that open into it • The liver is largely made up . Alimentary canal begins at of oil (its density is 0.95) and density of marine water is mouth and terminates in cloaca 1.03; liver facilitates . It is longer than the body and buoyancy includes buccal cavity, . Most of these contribute to the pharynx, oesophagus, stomach fast swimming of sharks and intestine • Sharks are the fastest aquatic . Mouth → Pharynx → swimmers Esophagus → Stomach → Intestine → Cloaca
SHARK SHARK . They are all similar in shape . Mouth – is wide crescentic (homodont), sharply pointed opening on the ventral side and directed backwards of head . They are arranged in several . It is bounded by folds of rows integument sometimes . If lost or destroyed they are called upper and lower lips. replaced by others several . Buccal cavity – mouth times in life time opens into a spacious dorso- (polyphyodont) ventrally flattened mouth . Teeth serve to grasp the prey cavity, lined by mucous which is usually swallowed membrane and bordered by whole the jaws . On the floor of the buccal . Teeth are not attached to the cavity lies the so-called jaw cartilages, but are 'tongue'. It is merely a thick, simply embedded in the skin flat, non-muscular, non- like other placoid scales glandular
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SHARK SHARK
. Pharynx – posteriorly the . Oesophagus – pharyngeal buccal cavity merges cavity narrows down insensibly with the larger posteriorly into a short but cavity of pharynx wide tube, with thick . Water & food are separated muscular wall in the pharynx, with the gill . Its mucous lining is thrown rakers preventing the food into longitudinal folds. from passing out through the . Stomach – the oesophagus gill slits passes backwards into the . Mucous lining of pharyngeal abdominal cavity to open wall contains numerous into a large muscular and U- dermal denticles (a small shaped stomach tooth-shaped scale with a . The oesophageal opening projecting spine, typical of into stomach is guarded by cartilaginous fish) an oesophageal valve
SHARK SHARK
. Production of pepsin & HCl is d/t from higher vertebrates . The inner mucous lining . At the end of stomach is of intestine becomes present a strong circular folded anticlockwise into a muscle band, called pyloric valve, guarding its opening longitudinal turns or folds into a small but thick-walled called spiral valve muscular chamber, the bursa . The last part of intestine is entiana called rectum . Intestine – bursa entiana is . A small finger-like caecal or followed' by intestine. rectal gland of unknown . It is a straight wide tube, function opens dorsally into receives the bile and the rectum. pancreatic ducts
SHARK SHARK Glands of alimentary canal . Liver – liver of dogfish is a massive yellowish bilobed gland . A narrow bile duct, leaves the gall bladder, and opens into the . The two lobes extend backwards freely into abdominal cavity, anterior end of the intestine but they are united anteriorly . Bile duct also receives branches from the lobes of liver . The gall bladder, in which bile is collected, lies embedded in the . Liver secretes bile, stores glycogen and fat, and destroys worn right lobe of liver out erythrocytes of blood
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SHARK SHARK
. Pancreas – it is a compact, whitish or pale bilobed gland . Caecal or rectal gland – it is a small finger-like body attached . The small pancreatic duct traverses the entire length of the by its duct to the dorsal side of rectum into which it opens gland to open into the intestine just opposite the opening of the . It is highly vascular and composed of lymphoid tissue but bile duct discharges a fluid in the intestinal lumen.
SHARK SHARK . Food is swallowed without mastication . Spleen – it is a large gland closely attached to the stomach . No digestion occurs in buccal cavity which lacks salivary . But it has no physiological relation with alimentary canal and glands functionally associated with circulatory system . The gastric juice in stomach contains pepsin and hydrochloric . It is a lymphoid organ which produces lymphocytes. acid . It digests protein but cannot chitin
SHARK SHARK
. Bile makes the semi-digested food alkaline in intestine while . Respiratory System pancreas secretes trypsin, amylase and lipase for digestion of . They depend wholly upon oxygen dissolved in sea water for proteins, starches and fats, respectively respiration; thus, respiration is carried on entirely by vascular gills . Spiral valve in intestine serves to retard the passage of food and . Their respiratory organs consist of 5 pairs of exposed (naked) gill affords a large surface for absorption of the products of slits digestion . During respiration, water taken into the mouth, passes through internal gill slits bathing gill lamellae and passes out of the external gill slits.
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SHARK SHARK Blood Vascular System . It lies within the pericardial . The circulatory system cavity in a two-layered comprises 4 parts : (i) Heart membranous pericardium. (ii) arteries, (iii) veins and (iv) . It is a reddish-brown, blood muscular and S-shaped tube Heart differentiated into a series of 4 . As in cyclostomes and other chambers: Sinus venosus → fishes, heart of Scoliodon Auricle, → Ventricle → Conus receives venous blood only arteriosus, arranged in tandem which it pumps into gills for formation aeration . Of these only two, the auricle . Such a heart is called a venous and ventricle, are considered or branchial heart to be true chambers so that . The heart is situated mid- heart is only two-chambered in ventrally in head beneath the fishes pharynx
SHARK SHARK . Sinus venosus is highly . Sinus venosus and auricle contractile and the beating of constitute the receiving the heart originates from this chambers of the heart. part of the heart . Whereas, ventricle and conus . A pair of membranous valves arteriosus constitute the prevent backward flow of forwarding' part of the heart. blood from auricle to sinus . Heart of Scoliodon receives venosus only deoxygenated or venous . Two pocket like valves blood (venous heart) prevent backward flow of . In a complete circuit of body, blood from ventricle to auricle the blood passes through heart . Cavity of conus arteriosus only once (single circulation) contains two transverse rows . Heart works like a muscular of semi-lunar valves to block pump for pumping its venous the or backward flow of blood blood to the gills for gas into ventricle. exchange
SHARK SHARK . The walls of the heart are . To achieve this, different parts supplied oxygenated blood of the heart rhythmically through special coronary contract at regular intervals arteries and in a definite succession, . Blood of Scoliodon consists of first sinus venosus, then colorless plasma and auricle, then ventricle and corpuscles suspended in it. finally the conus arteriosus . Corpuscles are of two types . Each contraction, called . RBC (erythrocytes) are oval systole, is followed by a and nucleated bodies and relaxation, called diastole. contain respiratory pigment, . Different valves of the heart haemoglobin and serve to prevent the backward . WBC (leucocytes) are flow of blood into preceding ameboid cells resembling with chambers through the lymphocytes of other apertures that they guide vertebrates
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SHARK SHARK Forebrain – Consists of cerebrum and Nervous System diencephalon. . The nervous system of Scoliodon . Olfactory lobe is situated in the consists of three parts forebrain . 1. Central nervous system. It Midbrain includes brain, and spinal cord . Optic lobe is situated in the . 2. Peripheral nervous system. It midbrain includes cranial and spinal nerves. . III and IV cranial nerves arise . 3. Autonomic nervous system. from midbrain. Brain Hindbrain . Brain of dogfish is more advanced . It comprises two parts, than that of the sea lamprey cerebellum and medulla . It lies enclosed within the oblongata. chondrocranium and is made of . V, VI, VII, VIII, IX and X cranial the same three basic parts of the nerves arise from medulla vertebrate brain-forebrain, . Hindbrain controls swimming midbrain and hindbrain movements
SHARK SHARK Sense Organs . The main receptor or sense organs of dogfish include (i) Cranial nerves Olfactory organs, (ii) Eyes, (iii) . Brain gives off 10 pairs of cranial Ears, (iv) Neuromasts or lateral nerves which are identified by their serial Roman numbers as well as line organs, and (v) Ampullae of names Lorenzini. . Besides, an additional pair of Olfactory organs anterior terminal nerves is present . Play a great role in the numbered as "O" because they were behaviour of fishes (vertebrates discovered long after the others were in general) – chemoreception is already numbered used for: . The serial numbers, names, origin . Procurement of food and distribution of cranial nerves in . Recognition of sex Scoliodon are almost similar to those . Discrimination b/n individuals of higher vertebrates; All are paired of the same species or d/t species . Defense against predators
SHARK SHARK
. Parental behaviour . Migration and orientation, etc . No connection b/n nostrils & . Olfactory organs include a pair of alimentary canal (buccal cavity) nasal or olfactory sacs situated . They are ventral and anterior to the ventrally in the snout one on either mouth side . Sharks are well equipped for their . They are characteristically large in predatory life elasmobranchs correlated with a . They track their prey using highly highly developed sense or smell for sensitive senses in an orderly sequence. perception of chemical substances . Sharks may initially detect prey from dissolved in water a kilometer or more away with their . Each olfactory sac is a large, oval, large olfactory organs, capable of ectodermal blind pouch covered by a detecting chemicals as low as 1 part thin membrane and housed inside the per 10 billion thin cartilaginous olfactory capsule of the skull
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SHARK SHARK . Eyes . Scoliodon has a pair of large and well developed eyes or . Sclerotic – Outer, cartilaginous layer photoreceptors Cornea – exposed, transparent in w/c . These are housed in socket light comes into the eyeball like depressions, the orbits, . Choroid – Internal layer Blood one on either side of cranium vessels & nerves (mostly cranial) are . The eye ball is elliptical in found. Iris and pupil control entry of light into the retina shape; The lateral eyes are . Retina – hind layer. Rods & cones lidless (the light sensitive cells); no cones in . The eye ball remains attached sharks to the inner wall of orbit by 6 . Eyes in sharks are large but far eye muscles and a separated, so that binocular vision is not possible cartilaginous stalk . Eye with 3 concentric circles – 3 layers are found
SHARK SHARK
Internal ears . In dogfish there are no external or . The main function of utriculus & middle ears sacculus is to maintain posture- . Only an internal ear is present called static equilibrium- (the position membranous labyrinth. of the body, mainly the head, . It is a delicate membranous sac relative to the earth’s surface i.e. found embedded in the cartilaginous with respect to gravity olfactory capsule, one on either . The main function of posterio-lateral side of cranium semicircular canals is to maintain . Each labyrinth consists of 3 semicircular canals filled with the dynamic equilibrium (the fluid known as endolymph and 2 maintenance of the body’s sacs (utriculus and sacculus) position in response to sudden . In this fluid there are particles of movements such as rotation, CaCO3 known as otoliths - hard acceleration & deceleration cartilaginous parts (may be used to . There is no evidence on the determine the age of the animals like hearing of sharks. scales)
SHARK SHARK
Lateral lines - A faint lateral line runs along either lateral side of Neuromast or lateral line system trunk and tail . It is a system of sense organs . It contains below the surface a concerned with life in water slender mucus-filled canal . Besides fishes, it is also found sunk into dermis in cyclostomes and aquatic . It opens to the surface by stages of Amphibia minute pores at intervals . In dogfish it includes through a series of vertically (1) Lateral lines, running tubes (2) Neuromast organs, and . The two lateral line canals are (3) Pit organs continued anteriorly into a system of canals
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SHARK SHARK Neuromast organs - These are little groups of receptor and Pit organs – Small ectodermal supporting cells found in the pits are found scattered on the lateral line canals dorsal and lateral surfaces of . Receptor or sensory cells bear head of dogfish tiny stiff sensory hairs which . Each pit organ consists of project into the canal. sensory hair cells with . Neuromast organs are supporting cells and rheoreceptors or current innervated by nerve fibers of receptors VII cranial nerve . They can perceive vibrations . Pit organs are regarded to be of very low frequency and isolated individual detect disturbances in water neuromasts or rheoreceptors such as caused by the . They are especially abundant movements of other fishes in rays
SHARK SHARK
Endocrine System Ampullae of Lorenzini - . Very little change from the plan electroreceptors of mammals . Located primarily on their i. Pituitary gland head . a. Anterior pituitary is evident . Sensitive to minute electrical in sharks & responsible for the currents in the water production of TSH, growth . Sense weak electrical currents hormone associated with the . b. No evidence of posterior functioning of nerves & pituitary – produces vasopressin muscles in living animals. (ADH) & oxytocin . Sharks may use ii. Thyroid gland – prominent electroreception to find prey . Produces thyroid hormone that buried in the sand is responsible for regulation of metabolic rate, growth & development
SHARK SHARK iii. Adrenal glands/ tissues in sharks iv. Islets of Langerhans – evident • Have two parts in sharks • a. Inner portion (adrenal . a. Beta cells – produce insulin medulla) – supra renal tissues- which is responsible for produce adrenaline reducing blood glucose (epinephrine) & noradrenalin . b. Alpha cells – produce (norepinephrine) glucagon which increase • b. Outer portion (adrenal glucose concentration in the cortex) – Inter renal tissues- blood by initiating the produces corticoides such as conversion of glycogen to aldosterone & cortisone glucose • No evidence for the presence of parathyroid gland
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SHARK SHARK v. Gonads – produce steroids . Ovaries & testes of most Urogenital System vertebrates produce 3 types of . The excretory and steroid hormones: estrogens, reproductive systems are so progesterone & androgens closely related to each other in . Interstitial cells of testes vertebrates that they are produce testosterone which is considered together under the responsible for primary & name of "urinogenital system“ secondary sexual characteristics . In Scoliodon, the two sexes are in males separate . Theca cells of the follicles . Sexual dimorphism occurs as around the ovaries produce in male dogfish, the medial estrogen which is responsible portions of pelvic fins are for primary & secondary sexual modified into claspers for characteristics in females transfer of spermatozoa during . Corpus luteum produces copulation progesterone
SHARK SHARK i. Male urinogenital system a. Excretory organs . Urea is the major nitrogenous . Excretory organs of male waste dogfish are a pair of long, . Normally urea is toxic in the flattened mesonephric kidneys blood, but sharks tolerate high . They are attached to the dorsal concentration of urea in the abdominal wall blood by adaptive mechanism . They extend nearly the whole (d/t from any other animal) length of the body cavity . There is a section in tubules . Each kidney is differentiated which regulates concentration into distinct anterior and of urea & salt in blood (it posterior parts keeps the blood isotonic to the . The anterior part is greatly environment – not to lose reduced, non-excretory, water narrower and genital in function, hence called epididymis
SHARK SHARK
. The posterior part is greatly . Posteriorly both the ureters developed, excretory, thicker open into a wide median and forms the functional adult urinogenital sinus, which itself kidney, called opisthonephros opens into cloaca through its . Each opisthonephros is formed aperture placed at the tip of a by several coiled, glandular short urinogenital papilla b. Reproductive organs uriniferous tubules with . Testes → Vasa efferentia → Vas Bowman's capsules enclosing deferens → Seminal vesicle → glomeruli Urinogenital sinus → Claspers . The tubules have a special . Spermatozoa developed from urea-absorbing segment in germ cells in seminiferous them tubules of the testis are carried . All the collecting tubules open to the vas deferens into a thin-walled common . In the seminal vesicle the kidney duct or ureter spermatozoa are stored
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SHARK SHARK ii. Female urinogenital system . The sinus in turn opens into a. Excretory organs cloaca at the tip of a short . In female dogfish also, the urinary papilla kidneys show the same b. Reproductive organs differentiation into anterior . Ovaries → Oviducts → Shell non-excretory and posterior gland → Uterus → Female excretory portions tube → Cloaca . But there is no connection between kidneys and genital Reproduction organs . Sexes are separate; there is . Unlike male, the two ureters sexual dimorphism; the of female dogfish unite into a gonads are usually paired and common median ureter with ducts opening behind into the large median urinary sinus
SHARK SHARK
b. Fertilization . As in all the elasmobranchs, a. Copulation fertilization in dogfish is . Reproduction occurs almost internal throughout the year . It takes place in the narrow . During copulation, the male anterior parts of oviducts in twines round the female front of the shell glands . Spermatozoa are transferred c. Development through the agency of grooved . Some dogfishes ovoviviparous erected claspers of male, one . Their eggs develop inside uteri or both of which are inserted so that they give birth to living into the cloaca of female young 3 to 7 embryos may develop in each uterus depending upon the species
SHARK CLASS CHONDRICHTHYES . Some sharks lay large, yolky eggs immediately after (CARTILAGINOUS FISHES) fertilization; these species are termed oviparous . Embryos are nourished from the yolk for a long period—6 to 9 2. Subclass Holocephali months in some, as much as 2 years in one species—before . Members of the small hatching as miniature replicas of adults. subclass Holocephali, . Many sharks, however, retain embryos in their reproductive distinguished by such tract for prolonged periods. suggestive names as ratfish, . Many are ovoviviparous species, which retain developing rabbitfish, spookfish, and young in the uterus while they are nourished by contents of ghostfish, are remnants of a their yolk sac until born line that diverged from the . Still other species have true viviparous reproduction shark lineage at least 360 . In these, embryos receive nourishment from the maternal million years ago bloodstream through a placenta, or from nutritive secretions, . Today there are only about “uterine milk,” produced by the mother 33 species . The gestation period is 6 months to 2 years . Arrogance in sharks is innate
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CLASS CHONDRICHTHYES CLASS CHONDRICHTHYES (CARTILAGINOUS FISHES) (CARTILAGINOUS FISHES) . Anatomically these fishes have several features linking . Chimaeras are not them to elasmobranchs, but commercial species and are they possess a suite of seldom caught unique characters, too . Despite their strange shape, . Instead of a toothed mouth, they are beautifully colored their jaws bear large flat with a pearly iridescence plates . Male has a frontal or . The upper jaw is completely cephalic clasper in addition fused to the cranium to usual pelvic claspers. . Their food includes seaweed, . All are oviparous and lay a molluscs, echinoderms, single egg at a time. have crustaceans, and fishes—a large eyes surprisingly mixed diet for such a specialized grinding dentition
Cone cells are present in sharks
VIDEO Binocular vision is possible
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) . Skin with many mucous glands, usually with embedded dermal scales of 3 General Characters types; Ganoid, Cycloid or . Inhabit all sorts of water— Ctenoid. fresh, brackish or salt; warm . Some without scales or cold. . No placoid scales. . Body spindle-shaped and . Endoskeleton chiefly of streamlined bone (Gr., osteon, bone + . Fins both median and paired, ichthyes, fish) supported by fin rays of . Cartilage in sturgeons (fishes valued for their flesh) and cartilage or bone some others • Tail is usually homocercal, . Notochord replaced by distinct vertebrae.
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) . Pelvic girdle usually small and simple or absent . Ventral heart 2-chambered (1 . Claspers absent auricle + 1 ventricle). Sinus . Mouth usually terminal venosus and conus arteriosus . Jaws usually with teeth present . Respiration by 4 pairs of • Erythrocytes oval, nucleated gills on bony gill arches, • Temperature variable covered by a common (poikilothermous) . Adult kidneys mesonephric operculum on either side. . Brain with very small . An air (swim) bladder often olfactory lobes, small present with or without duct cerebrum and well connected to pharynx • Lung-like in some bony fishes developed optic lobes and (Dipnoi) cerebellum. . No cloaca; but anus • Cranial nerves 10 pairs
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
. Well developed lateral line system . Internal ear with 3 semicircular canals . Sexes separate • Gonads paired • Fertilization usually external • Mostly oviparous, rarely ovoviviparous or viviparous • Eggs minute to12 mm • Development direct
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Classification of bony fishes i. Subclass Sarcopterygii (Gr. . Paired fins are lobed, with a sarkos, flesh, pteryx, fin, fleshy, bony central axis wing) covered by scales . Lobe-finned (fleshy-finned) . Diphycercal tail fishes . Intestine with spiral valve . Skeleton ossified . Usually with lungs . Single gill opening covered . Atrium and ventricle at least by operculum partly divided . Paired fins with sturdy . Teeth with enamel covering internal skeleton and . Olfactory sacs usually musculature within connected to mouth cavity appendage by internal . Divided into several groups
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Coelacanths . Most of them were marine Rhipidistians . In living coelacanths, the . The ancestor of tetrapods is swim bladder does not serve found within a group of in respiration but is filled extinct sarcopterygian fishes with fat called rhipidistians, . Size ranges from 0.75 to . Rhipidistians, such as slightly over 2 meters Eusthenopteron were . The scales have hollow cylindrical, large-headed tubercles, overlap each other fishes with fleshy fins, and to form a strong, thick presumably lungs protective covering . The first dorsal fin is unlobed and caudal fin has distinct 3 lobes.
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
Dipnoi (Lung fishes) . With paired lungs, can . Earlier lungfishes were breathe during periods when marine but modern forms oxygen levels in the water occupy fresh water fall during dry seasons . Three surviving genera . They breath both occur in continental streams atmospheric oxygen and and swamps dissolved oxygen . Protopterus – African . Their lungs are modified lungfish swim bladder . Lepidosirem – South . Modern lungfishes have a American lungfish skeleton composed mostly of . Neoceratodus – Australian cartilage, and exhibit a lungfish prominent notochord
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) ii. Subclass Actinopterygii . Double circulation for the (Gr., actis, ray + pteryx, fin) first time developed in this . Commonly known as “ray- group finned” fishes because of . Lungfishes are mostly their distinctive fins, which cartilaginous are internally supported by . They have specialized numerous slender, crushing tooth plates to endoskeletal rays feed effectively upon shell . Muscles that control fin fish. movements are located . Their tadpole like larva within the body wall, in has external gills as contrast to the muscles of accessory respiratory sarcopterygians that are located outside the body structure wall along the projecting fin
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
. Paired fins thin, broad, a. Chondrostei (Gr., without fleshy basal chondros, cartilage + osteon, lobes, and supported by bone) dermal fin rays . Mouth opening large . Olfactory sacs not . Scales usually ganoid connected to mouth . Tail fin heterocercal cavity . Primitive ray-finned fish . Divided into several . Example is Paddle groups fishes – naked skin; . chondrosteans, possess typical holosteans, and elongated rostrum & teleosts, heterocercal tail
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) b. Holostei (Gr., holos, entire + c. Teleostei (Gr., teleos, osteon, bone) perfect+ osteon, bone) . Mouth opening small . The modern bony fishes . Ganoid or cycloid scales . The most diverse & . Tail fin heterocercal abundant (successful) . Intermediate ray-finned fish, vertebrates transitional between . There are almost 30,000 Chondrostei and Teleostei described species, . There are two surviving representing about 96% of genera of early holosteans all living fishes or about half . Lepisosteus (Garpike) – of all vertebrates possess beak-like elongated . In addition, it has been jaws estimated that there are an . Amia (Bowfins) – possess additional 5,000 to 10,000 bone like dorsal fins undescribed species
CLASS OSTEICHTHYES CHARACTERISTIC FEATURES OF TELEOSTS (BONY FISHES) a. Head: . Head extends from tip of snout to hind edge of . Teleosts range in size from 7 mm adult minnows to 17 m operculum . oarfish and 900 kg Snout is depressed, short and not pointed . They exist in a variety of . Mouth is subterminal forms, mostly spindle shaped . It is a large transverse . They share similar structure and function with aperture, bounded by thick cartilaginous fishes despite a and fleshy lips . Snout bears dorsally a pair lot of differences of small nostrils, they are . Evolved in Mesozoic era peculiar as they do not communicate to the buccal cavity.
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CHARACTERISTIC FEATURES OF TELEOSTS CHARACTERISTIC FEATURES OF TELEOSTS b. Trunk: . It is the thick middle part of . The lateral eyes on head are body. and oval in cross without eyelids but protected section by a transparent protective . Back of operculum upto tail membrane constitute the trunk with . Behind the eye, on either lateral line side is a large movable bony . On the back of the middle of gill cover or operculum with trunk is a single large free posterior and ventral somewhat rhomboidal dorsal margins fin . Beneath each - operculum lie . Just behind operculum are a four comb-like gills in a pair of larger ventro-lateral branchial chamber pectoral fins, followed behind by a pair of smaller ventral pelvic fins
CHARACTERISTIC FEATURES OF TELEOSTS CHARACTERISTIC FEATURES OF TELEOSTS
. On either side of trunk extending from the back of c. Tail: operculum upto tail there is a . It comprises about one-third dark line on the mid ventral posterior part of body portion of the body called, . It is laterally compressed and lateral line narrower behind . On the back of the middle of . At the end of the tail is a trunk is a single large median homocercai caudal somewhat rhomboidal dorsal fin deeply notched into two fin similar lobes . Mid-ventrally at the . On the ventral side of tail is posterior end of trunk lie in a a median anal fin lying just series three small apertures: posterior to urinary aperture. anterior anus, middle genital . The tail makes the principal and posterior urinary locomotor organ.
CHARACTERISTIC FEATURES OF TELEOSTS CHARACTERISTIC FEATURES OF TELEOSTS Body wall . Trunk and tail are covered . Scales are found by thin, rounded, overlapping dermal cycloid embedded in the dermis. scales . The epidermis of fishes . The concentric or ring-like contains large mucous markings on scales called cells or Becker's cells circulii are used to and chromatocytes determine the age of fish . Chromatocytes are also . The skin comprises of two parts: outer epidermis and found in dermis inner dermis . Two type of sensory . The dermis is made up of cells viz., granular connective tissue, blood sensory cells and club vessels, nerves and smooth cells are also present muscle fibers.
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CHARACTERISTIC FEATURES OF TELEOSTS
Skeleton a. Exo and endoskeleton . Scales and finrays constitute the exoskeleton of Labeo rohita . Scales are cycloid type, thin Thank You overlapping bony plates, partly covered by skin . Exposed part of scales bear pigment cells . They are of two types- spines (single ray) and soft rays (segmented rays) . Bony endoskeleton is found in Labeo
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Digestive System . Pharynx is also dorso- Digestive system comprises the ventrally compressed and alimentary canal and the differentiated into a broad associated digestive glands anterior respiratory part and a. Alimentary canal a narrow posterior . Alimentary canal starts from masticatory part the mouth and terminates in . Anterior part is perforated the anal opening laterally by four pairs of . The subterminal mouth, internal gill slits leading into bounded by fleshy lips, branchial chambers opens into a broad, dorso- . From branchial arches ventrally compressed buccal project into pharyngeal cavity. cavity small spiny gill . Teeth and a distinct tongue rakers, to prevent passage of are lacking in rohu. food through gill slits
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) . Pharynx leads posteriorly into a short, narrow tubular . Opening between the two is oesophagus guarded by an oesophageal . Its mucous lining forms valve to prevent prominent longitudinal folds regurgitation of food . A pneumatic duct from air . The intestinal bulb has an bladder of fish opens dorsally anterior broader cardiac part into oesophagus. into which open dorsally the . Labeo and many other teleost pancreatic and bile ducts, fishes do not have stomach like higher vertebrates which and a posterior narrower is difficult to understand pyloric part without pyloric . Oesophagus opens behind caeca so common in other straight into an elongated, teleost fishes swollen, thick-walled . Gastric glands are lacking intestinal bulb
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
. Intestinal bulb is followed by a thin-walled, narrow and . Rectum opens to the exterior extremely elongated (about 8 by anus mid-ventrally just in metres long) intestine front of the anal fin . It is a much coiled tube of . It functions for the muscular practically uniform diameter expulsion of the faecal . Intestine is longer in Labeo material because of its herbivorous Digestive glands habit but it tends to be . Digestive glands of Labeo shorter in carnivorous fishes. are liver and pancreas . The rectum which follows is . Liver is a large, dark brown nearly 1 metre long, slightly gland wider and thin-walled . Rectal gland is lacking
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
. A thin-walled elongated sac- Air Bladder - it may constitute like gall bladder, 8 cm long 4-11% of the volume of the and 2.5 cm broad, lies body dorsally between right liver . Air bladder is also called the lobe and intestinal bulb swim bladder . Pancreas is rather diffused, . It lies in the body cavity, but found scattered in liver, outside coelom, above the spleen and intestinal intestinal bulb and ventral to mesentery the vertebral column. . It is an elongated white, thin- walled sac filled with a gas
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
. The other type of swim . The air bladder is connected bladder is known as to the roof of esophagus by a physoclistous, which is a slender pneumatic duct and closed type of swim bladder such a fish is called . It lacks pneumatic duct physostomous . The source of gas is . They inhale air at the water normally from the blood surface & push it through the contained in a network of pneumatic duct into the capillaries found in the swim bladder using a force lining of the swim bladder supplied by the buccal cavity . Most teleosts have this type . Examples of such bony of swim bladder fishes: Catfishes, Salmon, . Air bladder has several eels etc functions:
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
. The red bodies are located in . Air bladder functions like a the anterior chamber has hydrostatic organ extraordinary power of . It regulates specific gravity isolating oxygen, carbon of body by secretion or dioxide and nitrogen from the absorption of gas in the air blood and to fill this chamber bladder with these secreted gases . To keep position in water; . Besides acting as hydrostatic helpful for searching food organ it also performs a . The inner lining of the swim variety of other functions like- bladder is highly gas secretion, respiratory vascularized, forming red function, sensory function bodies auditory function and sound production etc.
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Respiratory System . Respiration of Labeo is aquatic, the fish depending on 0 dissolved in water. 2 . Possess hemibranch type of . The respiration is performed gills – because gill lamellae by four pairs of gills located are found in one side only in gill chambers. . . Teleosts respire by using 4 Efficiency of taking in H2O pairs of opercular gills with O2 is increased b/c of . Gill arches have supportive the presence of operculum – function opening & closing of the . Gill arch has teeth-like operculum facilitates the processes, the gill rakers, have entry of H2O with O2 protective function (do not permit food particles to enter the gill)
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
• Bulbus arteriosus is elastic & Circulatory System non-muscular; do not • The blood vascular system participate in pumping blood and physiology of (only ventricle is involved) circulation are practically the • In teleosts the spleen is very same as in the dogfish shark; distinct, partitioned and large there is only minor but diffused in sharks difference Nervous System • In teleosts bulbous arteriosus . The nervous and sensory is present instead of conus systems of a bony fish are arteriosus of sharks very similar to those of a • Conus arteriosus is muscular dogfish & helps ventricle to pump blood effectively
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Endocrine System . However, the brain of Labeo . Anterior & posterior pituitary bony fishes is more highly glands are evident in teleosts developed than that of but only anterior in sharks Scoliodon (cartilaginous fishes) . Teleosts possess . Olfactory lobes, cerebrum ultimobranchial bodies in the (undivided) and diencephalon gill region below the esophagus are somewhat smaller while the (it is related to parathyroid optic lobes and cerebellum gland) larger than in dogfish . It produces calcitonin – . Bony fishes share the keen important for Ca metabolism senses of smell and taste with . It picks Ca & phosphates from cartilaginous fishes the circulating blood; so these . The olfactory sacs do not ions can be utilized mainly for communicate with mouth bone formation, muscle cavity and take no part in contraction & nerve respiration transmission
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
Excretory System . Kidneys are largely involved . The kidney is mesonephric in osmoregulation type as that of . In fresh water, the chondrichthyes environment is hypotonic to . Ammonia and urea are the the body tissue of teleosts major wastes . Excess water must be . These wastes are eliminated removed; for these they have from the body mainly well developed glomeruli through gills not by and to conserve salt they mesonephric kidney have well developed tubules . Other minor wastes are like . In marine habitat, the creatine & uric acid released environment is hypertonic to through the kidney the body tissue of teleosts
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
Reproductive System . In chondrichthyes, sexes are . Water draws out from the totally separate but there are body; thus, glomeruli is hermaphroditic teleosts; both highly reduced/lost to retain simultaneous & sequential water hermaphroditic . For removing excess salt, . Most are oviparous; some they have chloride secreting are viviparous & cells in the gills which are ovoviviparous specialized to excrete excess . Identifying sexes by external salt out of their body morphology is very difficult in teleosts
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CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Production of light – bioluminescence . There are about40 families of luminous teleosts; mostly live in Some outstanding behavior of teleosts deep seas (eternal darkness) 1. Production of poison (venom) . Photophores are epidermal glands modified to function as light- a. Localized – produced from poison gland & the poison is emiting organs transmitted through duct . Light can be produced in two ways: . Use for defense or offense i. Produced chemically by the interaction of an enzyme . Depending on the dose it might be deadly to humans (luciferase) with a phenol (luciferine) b. Non-localized Luciferine →(Luciferase, ATP, O2) light . Fishes can be intoxicated by consuming toxic marine plants ii. Through bioluminescent bacteria that reside in specialized . Concentration increases from producers to consumers – gland like organs bioaccumulation (bimagnification) . Used for various purposes: . Human beings can be attacked as a result of consuming toxic a. For detecting prey – since there is no light in deep sea flesh b. For defense c. For communication
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES) Production of electricity . Not unique to teleosts, but production of electricity reach at its peak in teleosts Production of colour Migration . Teleosts are capable of changing their colours . Any mass movement of animals from one habitat to another with . Chromatophores – dermal cells producing a variety of colours characteristic regularity in time or according to life history; it has b/c of the presence of d/t pigments to be round trip . Melanophores (melanin- black); erythrophores (red); . Why animals do migrate? Most likely b/c of 3 reasons xanthophores (yellow); leucopores (white) i. For breeding – to search appropriate place . Compound chromatophores – more than one pigment ii. For feeding – when there is scarcity of food . B/c of movement of pigments in the skin, there is change of iii. For wintering – when the weather condition is unfavourable colour . Very important in fishes, amphibians and reptiles . Function – to conceal (hide) themselves by resembling the environment and for sexual recognition
CLASS OSTEICHTHYES CLASS OSTEICHTHYES (BONY FISHES) (BONY FISHES)
Several ways of migration Advantages of migration i. Diadromous - migration b/n 2 major types of water environments . For getting additional food sources, good climate & for breeding a. Anadromous : From sea to fresh water for breeding e.g. Chinook Disadvantages of migration salmon . Expenditure of energy: During the journey and spawning b. Catadromous : From fresh water to sea for breeding e.g. Eels . Exposure to predators: While moving longer distant places c. Amphidromous: From fresh water to sea or vice versa but not for Problem of adjusting osmoregulation breeding e.g. Mullests . Problem of adjusting themselves to the new environment, ii. Potamodromous: Fishes migrate within fresh water environment especially in the case of diadromous migration but in d/t habitats. It could be from upstream to downstream; from shallow to deep e.g. Barbus in Lake Tana to Rub river Reading assignment on the differences b/n sharks (cartilaginous iii. Oceanodromous: Fishes migrate within marine environment but fishes) and teleosts (bony fishes) in d/t habitats e.g. Tuna fishes
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Assignment: Enlist the name of the fishes that produce electricity and how they produce electricity
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ORIGIN OF TETRAPODS
VERTEBRATE ZOOLOGY The word "tetrapod" means "four feet" and LAND VERTEBRATES includes all species alive today that have four feet ORIGIN OF TETRAPODS AND THEIR FISH ANCESTORS — but this group also includes many animals that don't have four feet. That's because the group includes all the organisms (living and extinct) that By descended from the last common ancestor of Dr. K. S. Goudar amphibians, reptiles, and mammals.
ORIGIN OF TETRAPODS
So, for example, the ichthyosaur, an extinct swimming reptile, is a tetrapod even though it did not use its limbs to walk on land. So is the snake, even though it has Video no limbs. And birds and humans are tetrapods even though they only walk on two legs. All these animals are tetrapods because they descend from the tetrapod ancestor described above, even if they have secondarily lost their "four feet."
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ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
Tetrapods evolved from a Ray-finned fishes comprise finned organism that lived some 25,000 living species, in the water. However, this far more than all the other ancestor was not like most vertebrates combined. of the fish we are familiar They have fin rays — that with today. Most animals is, a system of often we call fishes today are ray- branching bony rays (called finned fishes, the group lepidotrichia) that originate nearest the root of this from the base of the fin. evogram.
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ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
That is, their limbs are In contrast, the other covered by muscle and animals in the evogram — skin. Some, such as coelacanths, lungfishes, all coelacanths, retain the other extinct animals, lepidotrichia at the ends of plus tetrapods have what these fleshy limbs, but in we call "fleshy fins" or most fleshy-finned animals "lobe fins.” these have been lost.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
Yet they also had air The common ancestor of all bladders (air-filled sacs) those different organisms connected to the back of (ray-fins, coelacanths, their throats that could be lungfishes, tetrapods, etc.) used for breathing air (i.e., was neither a lobe-fin nor a as lungs) or for buoyancy ray-fin. This ancient control. The air bladders of vertebrate lineage had fins many ray-fins no longer (with lepidotrichia), scales, connect to their throats, gills, and lived in the water. and so they are not able to breathe air.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
In these ray-fins, the air Lot of fossil forms that lived bladder is used mainly for between about 390 and buoyancy control and is 360 million years ago known as a swim bladder. during the Devonian By contrast, tetrapods have Period. During this interval, taken an alternative route: this lineage of fleshy-finned they have lost the organisms moved from the buoyancy control function water to the land. Many of their air bladders, and parts of the skeleton instead this organ been changed as new elaborated to form the innovations that permitted lungs that we all use to get life on land evolved. around on land.
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ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
This allowed them to look around in their watery The ancestors ray-fins, environments for predators coelacanths, lungfishes, and prey. However, as tetrapods, etc lived fully in ancestors of the first the water and had skulls tetrapods began to live in that were tall and narrow, shallower waters, their with eyes facing sideways skulls evolved to be flatter, and forwards. with eyes on the tops of their heads.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
This probably allowed them As lineages moved into to look up to spot food. shallower water and onto Then, as tetrapods finally land, the vertebral column moved fully onto land and gradually evolved as well. away from the water, many You may have noticed that lineages once again evolved fishes have no necks. Their skulls that were tall and heads are simply connected narrow, with eyes facing to their shoulders, and sideways and forwards, their individual vertebrae allowing them to look look quite similar to one around their terrestrial another, all the way down environments for predators the body. and prey.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
Mobile necks allow land animals to look down to Eventually, the second neck see the things on the vertebra evolved as well, ground that they might allowing them to move want to eat. In shallow their heads left and right. water dwellers and land Later tetrapods evolved dwellers, the first neck necks with seven or more vertebra evolved different vertebrae, some long and shapes, which allowed the some short, permitting animals to move their even more mobility. heads up and down.
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ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
The vertebrae you are probably most familiar with (like our own!) consist of a spool-like centrum, which Fishes swim with simple connects in front and back lateral motions, so their with other centra. On top arches are relatively of the centra are vertebral straight and needle-like, spines and arches to which and so are their ribs. When muscle segments attach, you eat fish and pick out and lateral to the centra are the bones, these are mostly the ribs; these anchor what you're finding. muscles that flex as the animals move.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
As the fleshy-finned organisms began to venture Because fishes live in the onto land, they evolved a water, gravity is not a big series of interlocking problem for them. But on articulations on each land, a quadruped with a vertebra, which helped backbone between them overcome the forelimbs and hindlimbs difficulty of interconnecting developed. and hold the backbone straight with minimal muscular effort.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS
Since the aquatic ancestors The connection between of fishes and tetrapods had the pelvis and hindlimbs in no such connection, one early tetrapods is a prime might guess that this example of expatiation. We feature first evolved serving call this fused connection the function of enabling the sacrum. It is extremely terrestrial locomotion. useful for terrestrial However, the earliest form organisms because it allows of this connection (as seen them to use their hindlimbs in Acanthostega) evolved efficiently for locomotion while these tetrapod on land. precursors were still living in the water.
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ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS Based on current evidence, Acanthostega appears to As the limbs and their have been fully aquatic, so connections to the rest of this connection likely the skeleton evolved, limb evolved to function in bones took on distinct roles something other than and many bones were lost. terrestrial locomotion. Only The humerus and the later, as tetrapod ancestors femur were already moved onto land, was this connected to two outer trait co-opted for terrestrial bones (the radius and ulna support — and as it was, in the forelimb, the tibia additional vertebrae were and fibula in the hindlimb). fused in the same way, providing further support.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS The ankle was originally composed of many small This is something that bones arranged in two rows, evolved about 30 million but gradually many of these years before vertebrates small bones were lost. The came onto land. However, first animals to get close to muscular connections walking on land had eight between these bones digits on each limb. Over began to change on the time, some of these digits road to land and allowed were lost, leading to animals the limbs to be used for with seven digits, then six, terrestrial locomotion. and then five, which is the common condition now seen in living tetrapods.
ORIGIN OF TETRAPODS ORIGIN OF TETRAPODS General adaptive changes (External): . Skin is keratinized . Scales and shells in reptiles . Feathers in birds As these animals evolved to live on land, other changes in . Hairs and layer of fat in the skin of mammals the rest of their bodies evolved. Many would eventually lose their gills, which only work well for getting oxygen General adaptive changes (Internal): when wet, and their tail fins got smaller. Similarly they . Development of large intestine for re-absorption of lost the lateral line system, a network of vibration- water from waste food material sensitive canals along the skull and jaw, which doesn't . Breathing by nostrils work out of water. . Modified eye and ear and nostrils . Eggs became shelled, embryos covered with fetal membranes
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VERTEBRATE ZOOLOGY
LAND VERTEBRATES Thank you CLASS AMPHIBIA
By Dr. K. S. Goudar
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GENERAL CHARACTERS GENERAL CHARACTERS . Skin soft, moist and . Aquatic or semiaquatic glandular. Pigment cells (freshwater), air and water (chromatophores) present. breathing, carnivorous, cold- . Exoskeleton absent. Digits blooded, oviparous, tetrapod clawless. Some with vertebrates. concealed dermal scales. . Head distinct, trunk . Endoskeleton mostly bony. elongated. Neck and tail may Notochord does not persist. be present or absent. Skull with 2 occipital • Limbs usually 2 pairs condyles. (tetrapod), some limbless. . Mouth large. Upper or both Toes 5 (pentadactyle) or less. jaws with small homodont Paired fins absent. Median teeth. Tongue often fins, if present, without fin protrusible. rays. . Alimentary canal terminates into cloaca.
GENERAL CHARACTERS GENERAL CHARACTERS
. Respiration by lungs, skin and mouth lining. Larvae . Kidneys mesonephric. with external gills which may Urinary bladder large. persist in some aquatic Urinary ducts open into adults. cloaca. Excretion ureotelic. . Heart 3-chambered (2 . Brain poorly developed. auricles+1 ventricle). Sinus Cranial nerves 10 pairs, venosus present. Aortic . Nostrils connected to buccal arches 1-3 pairs. Renal and cavity. Middle ear with a hepatic portal systems well single rod-like ossicle, developed. Erythrocytes columella. Larval forms and large, oval and nucleated. some aquatic adults with Body temperature variable lateral line system. (poikilothermous).
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GENERAL CHARACTERS
• Sexes separate. Male without copulatory organ. Gonoducts open into cloaca. Fertilization mostly external. Females mostly oviparous. • Development indirect. Cleavage holoblastic but unequal. No extra-embryonic membranes. Larva a tadpole which metamorphoses into adult.
CLASSIFICATION CLASSIFICATION
The living amphibians are represented by about 2,500 There are three orders in species, a very much smaller number than that of other Lissamphibia subclass principal classes of vertebrates. They are classified into two Sub classes. They are • Gymnophiona (A pod or • Stegocephalia (Extinct) Without foot) • Lissamphibia (living) • Urodela (Visible tail) • Anura (Without tail)
CLASSIFICATION CLASSIFICATION Order 1. Gymnophiona (A pod or Without foot) Order 2. Urodela (Visible tail) • Limbless, blind, elongated • Lizard-like amphibians with a worm like, burrowing tropical distinct tail. forms known as caecilians • (blind one). Limbs 2 pairs, usually weak, • Tail short or absent, cloaca almost equal. terminal, • Skin devoid of scales and • In some dermal scales tympanum. embedded in skin which is • Gills permanent or lost in transversely wrinkled. adult. • Skull compact, roofed with • Males without copulatory bone. organs. • Limb gridles absent. • Larvae aquatic, adult-like, • Males have protrusible with teeth. Ex. Triton copulatory organs. • Examples : Ichthyophis
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CLASSIFICATION CLASSIFICATION
Order 3. Anura (Without tail) • Specialized Amphibia without tail in adults. • Hind limbs usually adapted • Vertebral column very small for leaping and swimming. of 5-9 presacral vertebrae • Adults without gills or gill and a slender urostyle. openings. • Fertilization always external. • Eyelids well-formed. • Fully metamorphosed Tympanum present. without neotenic forms. • Skin loosely-fitting, scaleless; • Ex. frogs and toads Mandible toothless. • Pectoral girdle bony. Ribs absent or reduced.
EXTERNAL FEATURES– FROG EXTERNAL FEATURES– FROG Shape: body streamlined for Teeth: Small, conical, backwardly swimming and oval. Flattened pointed, acrodont, homodont dorso-ventrally and present only on upper jaw. Colour: Dorsal surface green Nostrils: Dorsally on snout, with black or brown patches. small, circular and serve for Ventral surface pale white. respiration Colour changes according to the Ear openings: No ear openings. background. Behind each eye present a Exoskeleton: Totally absent so circular patch of tight skin, the that skin surface is smooth. Tympanum, covering the middle Divisions of Body: consists of two ear cavity. regions only head and trunk Eyes: Eyes large, dorso-lateral Mouth: Large, terminal, and building. Pupil horizontal. semicircular, bounded by hard Lower eyelid movable. immovable lips Nictitating membrane present.
EXTERNAL FEATURES– FROG EXTERNAL FEATURES– FROG
Gill-slits: Gill slits found in Limbs: Paired fore and hind tadpole larva. Absent in adult. limbs present. Digits clawless.. Vocal sacs: A pair of oval, Hand with 4 fingers. Food with 5 wrinkled, bluish vocal sacs found toes having webs or transparent ventrally on throat of male frog skin for swimming. only Lateral lines: Absent in adult. Neck: Absent Instead a mid-dorsal line Copulatory Organ: Absent present. Scrotal sac: Absent Tail: Present in tadpole larva but Clocal Apertures: Small, terminal absent in adult frog and circular. Abdominal pores absent. Teats: Absent
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INTEGUMENT – FROG INTEGUMENT – FROG Skin surface and attachment: Epidermis: Many layered Thin smooth slimy and moist. epithelial cells which are Loosely attached to body wall stratified. Stratum corneum of due to subcutaneous lymph thin, flat and dead keratinized spaces below dermis. cells which sheds in patches.
Colour: Dark green on the back Dermis: Consists of outer loose and limbs with black and brown stratum spongiosum having patches and streaks but on the loose connective tissue, blood ventral side pale yellow. vessels and lymph space, and an inner stratum compactum having Ability to change in colour: skin dense connective tissue layer colour changes to harmonise with horizontal and vertical with the surroundings – a strands. Pigment cells also protective measure. present in dermis.
INTEGUMENT – FROG SKELETAL SYSTEM – FROG Pigmentation: Pigment cells • Well developed endoskeleton chromatophores are located in of bone and cartilage the upper portion of dermis. • Are specilized for jumping and swimming Glands: Multi-cellular mucus • Flexible characteristics of gland cells in stratum vertebral column was lost spongiosum which open at the because anurans move with surface of epidermis. limbs rather than swimming. • Exoskeleton: Absent. Vertebrae ranges from 9 to 285. Function: Protective, sensory , • Skull is lighter in weight, less gives texture to body. Respiration ossified flattened in profile. structure because permeable to • Front skull is well developed water than back of the skull
SKELETAL SYSTEM – FROG DIGESTIVE SYSTEM – FROG Major parts of alimentary Canal: 1. Buccal cavity • Limbs are having three joints 2. Pharynx (Hip, Knee and Ankle; 3. Oesophagus Shoulder, Elbow and wrist). 4. Stomach • Radius and ulna in the 5. Intestine forelimbs are articulated 6. Cloaca helps them to jump Mouth opening: Terminal along efficiently. anterior end of head. Large, • Tibia and Fibula of the hind semicircular, slit-like bounded by limbs are articulated as well. jaws. • Hind limbs are larger than Jaws and lips: Lower jaw forelimbs. movable. Lips hard, immovable, scaleless.
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DIGESTIVE SYSTEM – FROG DIGESTIVE SYSTEM – FROG Tongue: Large, muscular, sticky. Anterior end attached. Posterior end free bifid, highly protrusible Function of Teeth: Teeth small, and used for capturing insect conical, attached to bones and prey. Covered with few taste present on upper jaw only in a buds. single row Pharynx: Buccal cavity passes Buccal cavity: Large, wide and without demarcation into a short shallow. pharynx. Vestibule: Absent Gill slits: Spiracles and gill slits Palate: Absent. Skull forms roof absent. of buccal cavity. Eustachian Openings: A wide eustachian opening lies on roof, laterally near jaw angle, on either side.
DIGESTIVE SYSTEM – FROG DIGESTIVE SYSTEM – FROG
Stomach: Stomach large, broad, simple, curved, muscular sac, on Glottis: Floor carries a Mucous left side of body cavity. Anterior lining of slit like opening or glottis cardiac and posterior pyloric leading into laryngotracheal parts not marked off externally. chamber. Blind sac and cardiac valve Epiglottis: Absent absent. Esophagus: Short, wide, Bursa entiana and gizzard: Absent muscular with longitudinal mucous folds highly distensible Intestine: Long, coiled and and not clearly demarcated from narrow tube differentiated into pharynx and stomach. small and large intestines. Small intestine: Duodenum and ileum well marked
DIGESTIVE SYSTEM – FROG DIGESTIVE SYSTEM – FROG
Duodenum: Straight tube forming U with stomach. Receives bile and pancreatic Cloaca, abdominal Pores: ducts juice through a common Rectum opens through anus into hepato-pancreatic duct. a single sac like cloaca, also Ileum: Small and coiled Valves & containing Urinogenital villi. Mucous lining forms several apertures. Anal sphincter longitudinal folds, but spiral present but abdominal valves and villi are absent. pores and bursa Fabrici absent. Caecum: Absent Cloacal Aperture: Cloaca opens Vermiform Appendix: Absent at the hind end of trunk between Large Intestine: it forms a short hind limbs through a circular but broad rectum opening into cloacal aperture cloaca
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DIGESTIVE SYSTEM – FROG DIGESTIVE SYSTEM – FROG
Mucous glands: Present in Liver: Large, reddish brown and internal epithelial lining of bucco- 3- lobed : right, left and median. pharyngeal cavity and esophagus. Gall bladder: Large, spherical, Secrete mucus to lubricate greenish, situated ventrally passage of food. between two main liver lobes. Salivary glands: Absent Bile ducts: Bile duct passes Gastric glands: Present in through pancreas, receiving stomach lining secreting pancreatic ducts. Thus a pepsinogen and HCl. combined hepatopancreatic duct Pancreas: Much branched, opens into duodenum. irregular, cream coloured gland lying between stomach and duodenum.
RESPIRATORY SYSTEM – FROG RESPIRATORY SYSTEM – FROG
External nares: Dorsal on tip of Type of Respiration: Amphibious, snout. Small, circular apertures i.e., aquatic as well as aerial, as it without valves. Used in lives both on land and in water. respiration. Parts of respiratory Tract: Glottis & Epiglottis: Floor of includes external nares, nasal pharynx carries a median slit-like chambers, internal nares, bucco- aperture or glottis leading into pharyngeal cavity, glottis and laryngo – tracheal chamber. laryngotracheal chamber. Gill slits Epiglottis absent. and gill pouches absent. Larynx and Trachea: Fused Passage of Air: Air enters through forming a laryngo-tracheal external nares and leaves also chamber containing vocal cords. through them. Mouth not used Thyroid cartilage absent. for entry of air.
RESPIRATORY SYSTEM – FROG RESPIRATORY SYSTEM – FROG
Alveoli: Alveoli providing surface Respiratory Organs: Gills present for gaseous exchange few in in tadpole larva for aquatic number. Therefore central cavity respiration and lungs in adult for of lungs large. aerial respiration. Air sacs: Air sacs absent. Gills and gill Clefts: Tadpole larva Buccopharyngeal Respiration: use gills for aquatic respiration. Epithelial lining highly vascular so Gills Later disappear during metamorphosis. that bucco- pharyngeal respiration very effective. Lungs: 2 lungs, ovoid, thin walled, elastic hollow sacs of pinkish Cutaneous Respiration: Moist colour, suspended freely inside and richly vascular skin serves Peritoneal cavity. efficiently for exchange of gases.
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NERVOUS SYSTEM – FROG NERVOUS SYSTEM – FROG Three fundamental parts of the . Unlike eyes of most fishes, brain amphibian eyes at rest are adjusted for distant objects, . Forebrain, concerned with the and the lens is moved forward sense of smell; to focus on nearby objects . Midbrain, concerned with . Retina contains both rods and vision; cones, the latter providing frogs with color vision. . Hindbrain, concerned with . The upper lid of the eye is hearing and balance fixed, but the lower one is Lachrymal glands and eyelids folded into a transparent keep eyes moist, wiped free of nictitating membrane capable of moving across the eye dust, and shielded from injury surface – true for most terrestrial vertebrates
NERVOUS SYSTEM – FROG NERVOUS SYSTEM – FROG • The inner ear has 3 . Olfaction is equipped with semicircular canals and can mucous glands to solve produce true sounds desiccation problem • Taste buds are found on the . The pressure sensitive lateral- tongue & palate and able to line system of fishes remains discriminate salt and sour only in aquatic larvae of amphibians and in a few • Other sensory receptors strictly aquatic adult include tactile and chemical amphibian species receptors in skin • Endocrine system is concern . In frogs ear a middle ear more or less similar with closed externally by a large osteichthyes, but there is tympanic membrane (eardrum some advancement and containing a stapes) that • Parathyroid gland first transmits vibrations to the appeared in this group inner ear
EXCRETORY SYSTEM – FROG EXCRETORY SYSTEM – FROG
Excretory organs: Consists of a pair of kidneys, a pair of ureters, and Whole kidney is excretory. It is mesonephric kidney. urinary bladder and cloaca. Histology: Composed of a compact mass of uriniferous tubules, not Kidneys: Elongated, oval, flat, attached dorsally one on either side differentiated into cortex and medulla and ventrally covered by of the vertebral column in posterior abdominal cavity. Not peritoneum. differentiated into non excretory and excretory parts.
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EXCRETORY SYSTEM – FROG EXCRETORY SYSTEM – FROG Nephrostomes: Present Urinary bladder: Large, bilobed, thin walled elastic urinary bladder Uriniferous tubule or nephrons : Urea absorbing area and loop of opens ventrally into cloaca. Henle not differentiated. Glomerulus helps in urea filtration Nature of excretion: Ammonotelic in tadpole stage but ureotelic in Ureters: : Ureters or mesonephric ducts originate and run along adult because nitrogenous wastes are excreted mainly are urea outer surface of kidneys and open separately directly into cloaca. dissolved in water as urine. Urinogenital sinus not found.
CIRCULATORY SYSTEM – FROG CIRCULATORY SYSTEM – FROG
Chambers: 3-chambered, made of Position of heart in body: Heart 2 auricles and 1 ventricle. Auricles lies midventrally beneath not demarcated externally. oesophagus in thoracic cavity. Besides, sinus venosus and Septum transversum is absent. truncus arteriosus also present. Pericardium: Heart lies enclosed Sinus venosus: Triangular, dark by a thin, transparent 2-layered coloured, attached dorsally over sac, the pericardium. auricles and ventricles. Receives Size, shape and colour: Small, venus blood by 3 venae cavae : somewhat conical or triangular two anterior precavals and one and reddish in colour. posterior postcaval, joining at its angles
CIRCULATORY SYSTEM – FROG CIRCULATORY SYSTEM – FROG
Sinus-atrial aperture: Sinus opens into dorsal wall of auricle by a large, oval, sinu-atrial Atrial wall: Thin walled, without aperture guarded by a pair of muscular processes. flaplike valves. Auricular appendix: Absent Atria or auricles: Auricles Pulmonary veins: A common somewhat rectangular. Do not pulmonary vein opens into left form auricular appendages. auricle. Internally divided completely into right and left auricles by an interauricular septum.
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CIRCULATORY SYSTEM – FROG CIRCULATORY SYSTEM – FROG
Aortic arches: Truncus bifurcates Auriculoventricular aperture & anteriorly into right and left valves : Both auricles open into trunks each dividing into 3 aortic ventricle posteriorly through a arches : common carotid, common large auriculo- systemic and pulmocutaneous. ventricular aperture guarded by 2 Working: Heart receives venous pairs of flaplike valves. as well as oxygenated bloods. It Ventricles: Small, conical, thick supplies mixed blood to different walled undivided chamber lying regions of body. Called posterior to auricles. No transitional heart with a single interventricular septum. circulation.
REPRODUCTIVE SYSTEM– FROG REPRODUCTIVE SYSTEM– FROG
Male reproductive system: Sexual dimorphism: Indirect but during breeding season male frog consists of pair of testes, vasa develops nuptial pad at the base of first finger to clasp the female efferentia, paired urinogenital frog in amplexus ducts and cloaca. Testes: small, rod like, oval bodies, yellowish in colour attached to antero-ventral surface of kidneys. Scrotal sacs: Absent Vasa efferentia: emerge from inner end of testis and enter kidney to join Bidder’s canal which opens into urinogenital duct. Epididymis: Not found
REPRODUCTIVE SYSTEM– FROG REPRODUCTIVE SYSTEM– FROG
Vasa deferentia: vas deferens of Female reproductive system: each side unite with the ureter of consist of a pair of ovaries, its side to form urinogenital duct oviducts and cloaca. which opens separately in the Ovaries: Paired, large, irregular, roof of cloaca. lobulated structures situated Seminal vesicle: Terminal part of near kidneys attached to dorsal urinogenital duct enlarges to form abdominal. seminal vesicle. Epigonal organs: Not found Sperm sacs: Not found. Copulatory organs: No copulatory organs
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REPRODUCTIVE SYSTEM– FROG REPRODUCTIVE SYSTEM– FROG
Oviducts: oviducts are very long and much coiled glandular Vagina and vestibule: vagina and opening behind into cloaca. Their vestibule absent. Ovisacs directly anterior ends possess separate open into cloaca. wide oviducal funnels having Vulva: Absent. Cloaca opens out opening called Ostia at base of through a small circular aperture. the lung. Accessory reproductive glands: Shell glands: Not found Not found Uterus : Uterus is absent but each Fertilization: external oviparous oviduct is dilated to form ovisac before opening into cloaca.
VERTEBRATE ZOOLOGY
AMNIOTES Thank you ORIGIN OF AMNIOTIC EGG AND ITS STRUCTURE BRIEF EVOLUTIONARY ORIGIN OF REPTILES
By Dr. K. S. Goudar
87
ORIGIN OF AMNIOTIC EGG AND ITS ORIGIN OF AMNIOTIC EGG AND ITS STRUCTURE STRUCTURE The origin of the amniotic egg is a fascinating evolutionary problem, but it is still poorly understood because the fossil record Assignment does not provide much Draw neat diagram and label the amniotic egg evidence on this Explain the role of each embryonic membrane problem. But this type of egg has developed to meet the challenges of dryness as these animals started living on land.
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BRIEF EVOLUTIONARY ORIGIN OF REPTILES BRIEF EVOLUTIONARY ORIGIN OF REPTILES
It is generally agreed that primitive reptiles originated from some primitive labyrinthodont (Amphibia) and some One of the members of the labyrinthodont amphibians Cotylosauria was Seymouria, gradually took on reptilian found in the Lower Permian of characters. These earliest reptiles Texas (U.S.A.), perhaps 250 million are called the stem reptiles. They years old. Structure of Seymouria belong to the order Cotylosauria was intermediate between the of the subclass Anapsida. The amphibians of that time and the transition was so gradual that early reptiles. often it is difficult to decide whether some fossil skeletons are those of advanced amphibians or primitive reptiles.
GENERAL CHARACTERS GENERAL CHARACTERS
. Predominantly terrestrial, • Exoskeleton of horny creeping or burrowing, epidermal scales, shields, mostly carnivorous, air- plates and scutes. breathing, cold-blooded, • Skin dry, cornified and devoid oviparous and tetrapodal of glands. vertebrates. • Mouth terminal and bear . Body bilaterally symmetrical simple conical teeth. In and divisible into 4 regions— turtles teeth replaced by head, neck, trunk and tail. horny beaks. • Alimentary canal terminates • Limbs 2 pairs, pentadactyle into a cloacal aperture. (5 digits). Digits provided • Endoskeleton bony. Skull with horny claws. However, with one occipital condyle limbs absent in a few lizards (monocondylar). and all snakes.
GENERAL CHARACTERS GENERAL CHARACTERS . Lateral line system absent. • Heart usually 3-chambered, Jacobson's organs present in 4-chambered in crocodiles. the roof of mouth, helps in Sinus venosus reduced. 2 moisture-borne odour particles systemic arches present. Red detection. . Sexes separate. Male usually blood corpuscles oval and with muscular copulatory nucleated. Cold-blooded. organ. • Respiration by lungs . Fertilization internal. Mostly throughout life. oviparous. Large yolky • Kidneys metanephric. meroblastic eggs, always laid on Excretion uricotelic. land. Embryonic membranes • Brain with better (amnion, chorion, yolk sac and development of cerebrum allantois) appear during than in Amphibia. Cranial development. No nerves 12 pairs. metamorphosis. Young resemble adults. . Parental care usually absent.
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CLASSIFICATION CLASSIFICATION
The class Reptilia is divided into subclasses on the basis • Diapsida - Skull with of presence or absence of two temporal openings certain openings through on either side, the temporal region of the separated by the bar of skull. postorbital and • Anapsida - Primitive squamosal bones.(Ex. reptiles with a solid Tautora, Snakes, lizards skull roof. No temporal and crocodiles ) openings.(Ex. Turtles)
CLASSIFICATION CLASSIFICATION • Euryapsida Skull with a single dorso-lateral temporal opening on • Synapsida - Skull with a either side, bounded single lateral temporal below by postorbital opening on either side and squamosal bones bounded above by the (Extinct animals ) postorbital and squamosal bones. But we will see some (Mammals like animals) general characters of living animals they are categories into different orders. They are
CLASSIFICATION CLASSIFICATION Order Rynchocephalia (Snout head): • Body small, elongated • Vertebrae and lizard like amphicoelous or • Limbs pentadactyle, biconcave. Numerous clawed and burrowing abdominal ribs present. • Skin covered by • Teeth acrodont. granular scales and mid- • Heart incompletely 4- dorsal row of spines. chambered. • Skull diapsid. Nasal • No copulatory organ in openings Parietal male. foramen with vestigeal pineal eye present. Quadrate is fixed.
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CLASSIFICATION CLASSIFICATION • Oder Squamata (Scaly animal): • Teeth acrodont or • Advanced, small to pleurodont. medium, elongated. • Heart incompletely 4- • Limbs clawed, absent in chambered. snakes and lizards. • Cloacal aperture is • Exoskeleton of horny transverse. epidermal scales, • Male with eversible shields and spines. double copulatory • Skull diapsid. Quadrate organs movable. • (hemipenes). • Vertebrae procoelous. Ribs single—headed.
CLASSIFICATION CLASSIFICATION Order Chelonia (Turtle): • Body short, broad and . Skull anapsid, with a oval. single nasal opening. • Limbs clawed and/or . No sternum is found. webbed, paddle-like. . Teeth absent. Jaws with • Body encased in a firm horny sheaths. . Cloacal aperture a shell of dorsal carapace longitudinal slit. and ventral plastron, . Heart incompletely 4- made of dermal bony chambered with a partly plates. Thoracic divided ventricle. vertebrae and ribs . Copulatory organ single usually fused to and simple. carapace.
CLASSIFICATION CLASSIFICATION
Order Crocodilia (Crocodile): • Ribs bicephalous. • Large-sized, carnivorous Abdominal ribs present. and aquatic reptiles. • Teeth numerous, • Tail long, strong and thecodont, lodged in laterally compressed. sockets. • Limbs 'short but • Heart completely 4- powerful, clawed and chambered. webbed. • Cloacal aperture is a • Skin thick with scales. longitudinal slit. • Skull diapsid. A • Male with a median, seudopalate present. erectile, grooved penis.
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DIFFERENCES BETWEEN LIZARD AND SNAKE DIFFERENCES BETWEEN LIZARD ANDSnake SNAKE Snake Lizard Mandibular rami Lizard Body slender, narrow, Two rami of mandible joined by an elastic Body elongated, snake like. firmly united ligament and can be lizard-like. Absent, vestigial hind anteriorly. Mouth widely separated Limbs and girdles limbs and pelvic girdle non-expansible. during swallowing of usually well- in python. Sternum, epistemum large prey. developed. Eyelids fixed. and urinary bladder Sternum, epistemum Eyelids movable. Nictitating usually present. and urinary bladder Nictitating membranes absent. Premaxillae bear usually absent. membranes present. Auditory openings conical teeth. Premaxillae are Ear openings and and tympanum lost. Tongue rarely notched toothless. tympanum present. These skull bones or extensile. Tongue slender, bifid Maxillae, palatines freely movable Caudal autonomy with and extensile. and pterygoids fixed. helping in biting regeneration in some. Caudal autonomy mechanism does not occur.
DIFFERENCES BETWEEN LIZARD AND SNAKE EXTINCTION OF DINOSAURS
Snake Extinction of animals is Lizard Left lung greatly nothing but no longer Both lungs equally reduced. existing in this world. During developed. About 3,000 living cretaceous period there was About 3,800 living species. mass extinction of reptiles. species. Occipital condyle There are several prevailing Single occipital distinctly triple. condyle. theories. Jagal bone absent. Jagal bone present. Geological & cosmological Extremely elongated Cerebral hemispheres hazards: and project between are short. There were many earth the eyes. Cranial nerves 12 quakes, volcanic eruptions Cranial nerves 10 pairs pairs. and showers of meteors only. from supernova.
EXTINCTION OF DINOSAURS EXTINCTION OF DINOSAURS
Meteor – a piece of rock Mammals: Mammals used to feed on the egg of from outer surface that dinosaurs (& other giant reptiles) makes a bright line across Epidemic diseases: the night sky as it burns up Might have occurred and affect those giant reptiles while falling through the Fluctuations in climate – The most accepted and earth’s atmosphere supported by paleoclimatologists that birds and mammals Supernova – a star that could resist this fluctuation (b/c they are homeotherms). suddenly becomes much However, those large reptiles had no means of regulating brighter b/c it is exploding their body temperature (since they were poikilotherms). But, the question is why They needed shade to escape extremely hotness or other vertebrates survived? coldness
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EXTINCTION OF DINOSAURS EXTINCTION OF DINOSAURS
But, how did smaller amphibians and reptiles resist? Since they were small, they had large surface area to Assignment volume ratio; they can hide themselves in small bushes, Enlist the differences between Crocodile and Alligator under stones, etc (have place to escape)
VERTEBRATE ZOOLOGY
AMNIOTES Thank you CLASS AVES THE ORIGIN OF FEATHER AND FLIGHT
By Dr. K. S. Goudar
117
THE ORIGIN OF FEATHER AND FLIGHT THE ORIGIN OF FEATHER AND FLIGHT
Birds are sometimes referred to as reptiles with feathers, but we know nothing about the evolution of feathers from the reptilian scales, although intermediate structures between scale and feather are present on the legs of ostrich and fowl.
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THE ORIGIN OF FEATHER AND FLIGHT THE ORIGIN OF FEATHER AND FLIGHT
We of course, do not know just how flight evolved in the ancestors of Archaeopteryx. It is possible that the ancestors Different views have been were becoming more active expressed to explain the and possibly warm blooded origin of flight in birds, and feathers developed from starting from either a scales primarily to conserve terrestrial bipedal and their body heat. Later, the cursorial (Adopted for feathers enlarged on the limbs running) ancestor or an and the tail probably to confer arboreal ancestor. stability in fast running on ground or in rudimentary gliding from low branches.
THE ORIGIN OF FEATHER AND FLIGHT THE ORIGIN OF FEATHER AND FLIGHT
Theory of cursorial origin of flight: Gradually, the forelimbs According to this theory, the enlarged due to fraying out ancestors of birds were long- or elongation of scales tailed, cursorial, bipedal forming quill-feathers animals. They were fast through the processes of runners who leaped on their mutation and selection. In strong hind limbs and the end, the forelimbs flapped their forelimbs in air became organs of flight or to help them along, as do wings rather than many modern birds that run accessories to rapid running. fast.
THE ORIGIN OF FEATHER AND FLIGHT THE ORIGIN OF FEATHER AND FLIGHT Compromise theory of origin of flight: Believers in the dual origin Theory of arboreal origin of of birds, maintain that some flight: birds evolved from arboreal The other theory postulates and others from cursorial that the ancestral birds were ancestors. arboreal creatures They Theory of division of origin: climbed trees from which This states that pro-aves they glided to the ground or were aquatic reptiles. Flight to other trees, like the might have started in modern living squirrels. connection with soaring over the water during diving for fishes.
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GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS • Limbs are two pairs. . Feather- clad, air- Forelimbs are modified breathing, warm- as wings for flying. Hind blooded, oviparous, limbs or legs are large, bipedal flying and variously adapted vertebrates. for walking, running, . Body is more or less scratching, perching, spindle-shaped and food capturing, divisible into four distinct swimming or wading, regions : head, neck, etc. Each foot usually trunk and tail. Neck is bears four clawed toes, long and flexible. Tail is of which the first or short and stumpy. hallux is directed backwards.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
• Exoskeleton is epidermal and horny, represented by Feathers are found only 1. Feathers forming a in birds and are modified non-conducting body covering for warmth, reptilian scales. They are 2. Scales on the legs, formed from the similar to those of epidermis in which the reptiles, stratum corneum is 3. Claws on the toes, highly specialized. and 4. Sheaths on the beaks
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS They form a protective covering, regulate body temperature and Feathers are light, support the body in strong, elastic and flight. There are three waterproof and show kinds of feathers in birds. many colours due to They are pigments and structural arrangement. 1. Contour feathers, 2. Down feathers 3. Filoplumes.
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GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
Those on the wings are Contour feathers: The remiges (flight feathers) contour feathers occur and those on the tail are all over the body. They rectrices (Larger feathers are of two types. Flight in a bird’s tail, used for feathers or quills are steering in flight). large in size. Coverts are smaller in size and cover the body.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
The rachis bears an A contour feather of expanded vane or flight has a stalk or quill. vexillum made of many Its basal part called parallel barbs on both calamus is embedded in sides of the rachis. Each the skin. The calamus is barb is a thin flat plate hollow and has pith bearing distal barbules formed from the dry on one side which have remains of the feather many curved hamuli of pulp. hooks.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS On the other side each barb has proximal barbules which have grooved edges. Hamuli Coverts are smaller than of distal barbules hook flight feathers and their over the grooved edges hamuli are poorly of proximal barbules developed they cover binding the barbs the body wings legs and together so that the tail. entire vane acts as one flat piece offering resistance to air.
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GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS Down feather or plumule: It has a very They are concealed in small quill having barbs contour feathers forming with barbules arising a dense layer in which no from its tip. They have air movement occurs. So no hamuli. In an adult that they do not permit the down feathers form loss of body heat and powder which powdery prevent freezing in clod fragments are dropped (a compact mass) upper for cleaning the strata. plumage.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
In a young one the down feathers cover the body Filoplumes: Filoplumes and are called nestling are delicate hair like down. They appear on feathers with a long the tips of developing slender stalk having a feathers and are soon few terminal barbs with worn off after temporary no hamuli they lay service on the young among contour feathers. ones.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
• Skin is dry and devoid of glands except the oil or preen gland at the root • Skull smooth and of tail. monocondylic, bearing a • Pectoral muscles of flight single occipital condyle. are well developed. Cranium large and dome- • Endoskeleton fully like. Sutures indistinct. ossified, light but strong. • Lower jaw or mandible Long bones pneumatic consist of 5 or 6 bones. or hollow and have no marrow. Usually, there is a fusion of bones.
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GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS • Vertebral column short. • Central of vertebrae Sternum large, usually heterocoelous (saddle - with a vertical, mid- shaped). ventral keel for • Cervical vertebrae numerous, attachment of large flight bear small cervical ribs. muscles. Some thoracic vertebrae • Ribs double-headed fused together. (bicephalous) and bear • A synsacrum results by fusion of posterior thoracic, lumbar, posteriorly directed sacral and anterior caudal uncinate processes. vertebrae. • Both clavicles and single • Tail vertebrae few, interclavicle fused to form compressed laterally and the a V-shaped bone, called last 3 or 4 fused into a furcula or wishbone. ploughshare bone, pygostyle.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
• Pelvic girdle large, strong • Proximal tarsals and tibia and fused with fused to form tibiotarsus. synsacrum throughout Distal tarsals fused with its length. II, III and IV metatarsals • Proximal carpals free. to form tarso- Distal carpals fuse with metatarsus. metatarsal three metacarpals to form remains free. carpometacarpus
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
• Oesophagus is frequently dilated into a crop for quick feeding and • Heart completely 4- storage. chambered. There is • Stomach divided into a neither sinus venosus glandular proventriculus nor truncus arteriosus. and muscular gizzard. Only right aortic Junction of small (systemic) arch persists intestine and rectum in adult. Red blood marked by a pair of corpuscles nucleated. rectal caeca. A three- chambered cloaca present.
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GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS
• Birds are the first vertebrates to have warm • Kidneys metanephric and blood. Body temperature is 3-lobed. Ureters open regulated into cloaca. Urinary (homoiothermous). bladder absent. Birds are • Respiration by compact, urecotelic. Excretory spongy, nondistensible substance of urates lungs continuous with thin- eliminated with faeces. walled air-sacs. • Brain large but smooth. • Larynx without vocal cords, Cerebrum, cerebellum A sound box or syrinx, and optic lobes greatly producing voice, lies at or developed. Cranial near the junction of nerves 12 pairs. trachea and bronchi.
GENERAL CHARACTERISTICS GENERAL CHARACTERISTICS • Olfactory organs poor. Middle ear contains a single ossicle. Eyes large and • Fertilization internal, possess nictitating preceded by copulation and membranes, sclerotic plates courtship. Females oviparous. and a vascular pecten. Eggs large with much yolk • Sexes separate. Sexual and hard calcareous shell. dimorphism often well • Eggs develop by external marked. Male has a pair of incubation. Cleavage abdominal testes and a pair discoidal, meroblastic. of sperm ducts. A copulatory Development direct. Extra- organ absent except in embryonic membranes ratites, ducks, geese, etc. (amnion, chorion, allantois Female has a single and yolk-sac) present. functional left ovary and oviduct.
GENERAL CHARACTERISTICS
• Newly-hatched young Video fully formed (precocial) or immature (altricial). • Parental care is well marked.
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ASSIGNMENT
Thank you Draw any one Ethiopian bird and write their classification and salient characteristics features
158
EVOLUTIONARY HISTORY OF THEIR ORIGIN
• Mammals have been VERTEBRATE ZOOLOGY thoroughly described and adequately classified. They include approximately 5,000 AMNIOTES living species (15,000 CLASS MAMMALIA subspecies) and numerous EVOLUTIONARY HISTORY OF THEIR ORIGIN fossil forms. • From the fossil record, we can trace the derivation over 150 million years of By endothermic, furry mammals Dr. K. S. Goudar from their small, ectothermic, hairless ancestors
EVOLUTIONARY HISTORY OF THEIR ORIGIN EVOLUTIONARY HISTORY OF THEIR ORIGIN
• Skull structures and especially teeth are the most abundant . The synapsid group, which fossils, and it is largely from includes the mammals and these structures that we their ancestors, has temporal identify the evolutionary openings in the skull descent of mammals. associated with attachment • The structure of the skull roof of jaw muscles permits us to identify three . Synapsids were the first major groups of amniotes amniote group to radiate that diverged in the Paleozoic widely into terrestrial era, the synapsids, anapsids, habitats and diapsids
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EVOLUTIONARY HISTORY OF THEIR ORIGIN EVOLUTIONARY HISTORY OF THEIR ORIGIN
• From one group of early • The earliest synapsids carnivorous synapsids arose radiated extensively into the therapsids, the only diverse herbivorous and synapsid group to survive carnivorous forms often beyond the Paleozoic collectively called • With therapsids we see for pelycosaurs the first time an efficient • Pelycosaurs share a general erect gait (walk) with upright outward resemblance to limbs positioned beneath the lizards, but this resemblance body, rather than sprawled is misleading out to the sides of the body, • Pelycosaurs are not closely as in lizards and primitive related to lizards pelycosaurs
EVOLUTIONARY HISTORY OF THEIR ORIGIN UNIQUE FEATURES OF MAMMALS • One therapsid group to • Since stability was reduced by survive into the Mesozoic era raising the animal from the was the cynodonts. ground, the muscular • Cynodonts evolved several coordination center of the features that supported a brain, the cerebellum, high metabolic rate: assumed an expanded role • Increased and specialized • Modifications in the jaw musculature, morphology of the therapsid permitting a stronger bite; skull and mandibular • Several skeletal changes, adductor muscles increased supporting greater agility feeding efficiency (Quickness) • Therapsids radiated into • Heterodont teeth, numerous herbivorous and permitting better food carnivorous forms processing and use of more diverse foods
UNIQUE FEATURES OF MAMMALS UNIQUE FEATURES OF MAMMALS
. Turbinate bones, in the • Loss of lumbar ribs in nasal cavity, aiding cynodonts is correlated with retention of body heat the evolution of a diaphragm . A secondary bony palate, and also may have provided enabling an animal to greater dorsoventral breathe while holding flexibility of the spinal column prey in its mouth or • The earliest mammals of the chewing food late Triassic period were small . The secondary palate mouse- or shrew-sized would be important to animals with enlarged crania, subsequent mammalian redesigned jaws, and a new evolution by permitting type of dentition, called the young to breathe diphyodont while suckling
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UNIQUE FEATURES OF MAMMALS UNIQUE FEATURES OF MAMMALS
• One of the more amazing transformations involved the three middle ear bones, the . Hair was essential for malleus, incus, and stapes, insulation, and the presence which function to transmit of hair implies that sebaceous sound vibrations in mammals • A new jaw joint was formed and sweat glands must also between the dentary and have evolved at this time to squamosal (temporal) bones. condition hair and to facilitate • This dentary-squamosal joint thermoregulation. is the defining characteristic for fossil mammals.
UNIQUE FEATURES OF MAMMALS UNIQUE FEATURES OF MAMMALS • The fossil record is silent on the appearance of mammary • Mammals survived, first as glands, but they must have shrew like, probably evolved before the end of the nocturnal, creatures. Triassic • Mammalian radiation was • The young of early mammals almost certainly promoted by probably hatched from eggs the facts that mammals were in a very immature condition, agile (lively), endothermic, totally dependent on intelligent, adaptable, and maternal milk, warmth, and gave birth to living young, protection which they protected and • This mode of reproduction nourished from their own occurs today only in milk supply. monotremes (Ex. Platypus)
CLASSIFICATION OF MAMMALS CLASSIFICATION OF MAMMALS
i. Subclass Prototheria (Gr. first, wild animal) • Primitive, reptile-like, oviparous or egg-laying mammals. • The main characters forming the basis of their classification into • Represented by a single order orders include : (3 species): Order • Mode of caring for their young Monotremata. Monotremes are • Nature of dentition mammals that lay eggs • Foot posture, (Prototheria) instead of giving • Nails, claws and hoofs birth to live young like • Complexity of nervous system marsupials (Metatheria) and placental mammals (Eutheria). Example: duck-billed platypus and spiny anteater
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CLASSIFICATION OF MAMMALS CLASSIFICATION OF MAMMALS ii. Subclass Theria • Divided into 2 infraclasses b. Infraclass Eutheria a. Infraclass Metatheria . Placental mammals without . Order Marsupialia – Pouched (marsupial) mammals marsupium . Born in a very immature state, . Young born in a relatively and complete their development advanced stage attached to teats or nipples in . Dentition never exceeds the abdominal pouch or marsupium. 3.1.4.3/ 3.1.4.3 = 44. . Usually 3 premolars and 4 . Eutherians constitute the molars in each jaw on either vast majority of living side mammals arranged in 16 . E.g. Opossum, Wombat, orders Bandicoots, etc
CLASSIFICATION OF MAMMALS
VERTEBRATE ZOOLOGY
VERTEBRATE OF DIVERSITY OF ETHIOPIA
By Dr. K. S. Goudar
VERTEBRATE OF DIVERSITY VERTEBRATE OF DIVERSITY
Ethiopia is one of the most physically and biologically diverse countries in the world with unique environmental The diversity and endemism of Ethiopian fauna are high. It conditions and varied topography from vast plains to high consists of 862 species of birds, 288 species of mammals, mountains having an altitudinal range of 110 m below sea 201 species of reptiles, 64 species of amphibians and 150 level (Kobar sink) in the Afar depression to the highest species of fish. Among these, 31 species of mammals, 17 peak of 4620 m above sea level (asl)(Ras Dashen) in the species of birds, 30 species of amphibians, 9 species of Siemen Mountains. The country has more than 300,000 reptiles and 40 species of fish are endemic to Ethiopia km2 of land area above 2000 m,(asl) and over 25,000 km2 (Jacobs and Schloeder, 2001) area above 3000 m asl, which forms more than 80 % of all the Afro-Alpine habitat.
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VERTEBRATE OF DIVERSITY VERTEBRATE OF DIVERSITY
Bale Mountains Vervet: This species was previously Gelada baboon: The gelada classified as Data Deficient baboon bleeding-heart but is now Vulnerable baboon, is a species of Old according to the IUCN World monkey found only in (IUCN, 2008). There is no the Ethiopian Highlands, definitive information about with large populations in population size but the the Semien Mountains. trend is said to be decreasing.
VERTEBRATE OF DIVERSITY VERTEBRATE OF DIVERSITY
Bale Shrew: The Bale Shrew Ethiopian Highland Hare: is a species of mammal. It is The Ethiopian highland hare endemic to Ethiopia. Its is a species of mammal. It is natural habitats are endemic to the Ethiopian subtropical or tropical moist Highlands, where it is montane forests and almost entirely restricted to subtropical or tropical high- altitudes above those of altitude grassland. It is other African hares. threatened by habitat loss.
VERTEBRATE OF DIVERSITY VERTEBRATE OF DIVERSITY
Bale Long-eared Bat (Flaying mammal): This recently described species is endemic to the Ethiopian Ethiopian Woolly Bat highlands were it is (Flaying mammal): It is currently known only with found only in Ethiopia. certainty from the upper belts of the Harenna Forest in the Bale Mountains National Park and from Abune Yosef
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VERTEBRATE OF DIVERSITY VERTEBRATE OF DIVERSITY
Ethiopian Wolf: The Ethiopian wolf is a canid Mountain Nyala: Mountain native to the Ethiopian nyala are endemic to the Highlands. It is distinguished Ethiopian highlands by its long and narrow skull, southeast of the Rift Valley. and its red and white fur
VERTEBRATE OF DIVERSITY VERTEBRATE OF DIVERSITY
Big-headed Mole Rat: Also known as the giant root-rat, Walia Ibex: is an endangered Ethiopian African mole-rat, species of ibex. Only about or giant mole-rat. It is 500 individuals survived in endemic to Ethiopia's Bale the mountains of Ethiopia, Mountains. Its natural concentrated in the Semien habitat is subtropical or Mountains. tropical high-altitude grassland
VERTEBRATE OF DIVERSITY
Assignment Thank you Enlist the Ethiopian endemic animals(Mammals, Birds, Reptiles, Amphibians and Fishes)
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