BLY102 (GENERAL BIOLOGY II)
ANIMAL DIVERSITY INTRODUCTION
• Animal diversity deals with natural history, classification, characteristics ,conservation and distribution information on thousands of animal species. • About 1.3million living species have been identified. • With this large variety of animals scientists must find a meaningful way of classifying, identifying and naming them.
Olatubi I.V 2 CLASSIFICATION
• Generally, all animals are grouped into these ranks. • Kingdom • Phylum • Class • Order • Family • Genus • Species
Olatubi I.V 3 IDENTIFICATION
• All animals are given two names termed ‘Binomial Nomenclature’ • First name is from the Genus the animal belongs • Second name is the name of the Species to which it belongs • For example; Homo sapiens
Olatubi I.V 4 FEATURES OF ANIMALS • Some features common to all animals are highlighted below: • Mode of Nutrition: Heterotrophic. • Cell structure (Eukaryotes, no cell wall, body held together by structural proteins such as collagen) • Nervous and muscle tissues are unique to animals. • Reproduction is sexual with diploid stage dominating life cycle: • Cleavage: either spiral in Protostome or radial/ intermediate in Deuterostome. • Possess at least one larval stage
Olatubi I.V 5 FEATURES OF ANIMALS cont’d • Hox genes (unique to animals): regulates the development of body forms. • Body plan (radial/bilateral, cephalization (head)). • Tissues: ectoderm(embryo surface), endoderm (archenteron),mesoderm. • *diploblastic, triploblastic • Body cavity: true coelom(derived from the mesoderm),pseudo: derived from the mesoderm and endoderm.
Olatubi I.V 6 THE PROTOZOA
• Derived from the greek word protos=first, zoon=animal. • They are the first assemblage of eukaryotic unicellular organisms with animal like features. • protozoans are the simplest forms of animal life Characteristics They are unicellular organisms but some are with multicellular stages in their life cycle. They show an amazing degree of differentiation at their protoplasmic level of organization. They are mostly microscopic. Many have no body axis no plane of symmetry and bodies are not divided into cells no tissues no organ. They posses functional units termed organelles.
Olatubi I.V 7 THE PROTOZOA ‘xtics cont’d Locomotion is by any of the three organelles; pseudopodia, flagella and cilia. Nutrition is either autotrophic or heterotrophic. Heterotrophic forms may also be saprozoic taking in dissolved substances in their surrounding by diffusion active transport or pinacytosis. Reproduction is by Asexual and Sexual means. asexual reproduction is by binary fission, multiple fission or schizogony and budding. In sexual reproduction when nuclear material is exchanged between mates the sexual reproduction is called conjugation. Embryonic development does not occur some protozoans. occur in colonies and certain colonials 2 types of vacuoles are present food vacuole Into which food accumulates. contractile vacuole or water expulsion vesicles(wev) which function principally in osmoregulation
Olatubi I.V 8 CLASSIFICATION
It is difficult to classify protozoans particularly on the account of numerous modification of their life cycle but has been classified into four classes based on its locomotary organs 1. Class Rhizopoda - Locomotary organ: pseudopodia Mostly free living, some are parasitic Examples: Amoeba, Entamoeba 2. Class Mastigophora/ Flagellata - Locomotory organ: Flagella Free living or parasite. Body covered with cellulose, chitin or silica. Examples: Giardia, Euglena, Trypanosoma
Olatubi I.V 9 CLASSIFICATION cont’d
3. Class Sporozoa - Locomotory organ: Absent Exclusively endoparasites Examples: Plasmodium, Monocystis 4. Class Ciliata - Locomotary organ: Cillia Nuclei two types i.e. Macronucleus and Micronucleus. Examples: Paramecium, Voricella, Blantidium
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Olatubi I.V 1 PHYLUM PORIFERA Derived from Latin words “porus”= pore and “Ferre” = bear Characteristics Sponges are multicellular organisms having a variety of shapes. Some form crusts, some are simple tubes, some are vase shape while others can be cup shaped, massive clumps, fan shaped, finger like bulges, treelike or even bushy. They maybe soft, brittle or hard and asymmetrical but some are radially symmetrical. They posses Spicules which forms the skeletal structure where they interlock to form a delicate framework of tubes inside and outside the body and on this basis they are classified. False body cavity and all the cells and tissues surround a water filled space.
1 Ola tubi I.V 1 PHYLUM PORIFERA cont’d Members also possess: a few tissues with no organs. Three main layers of their body structure are: a layer of flattened epidermal cells, a semi fluid matrix and a layer of flagellated collar cell. Numerous pores by means of which water and other plankton enter the sponge body. Also used to control water flow through the spongocoel (body cavity). Flagellated cells to circulate water through a unique system of water canals. No proper digestive, nervous or circulatory system. Unique water canal system which are of three types – Asconoid, Syconoid and Leuconoid. 2
Olatubi I.V 1 PHYLUM PORIFERA cont’d The power of cell aggregation is tremendous in sponges. If cut into a million minute pieces, they can still come together and re-form into a fully functional sponge. Excretion and respiratory (gas exchange) occurs by simple diffusion Most cells of freshwater sponges contain contractile vacuoles for osmoregulation. Reproduction can be asexual or sexual; Asexual reproduction is either by fragmentation or budding Sexual reproduction is by the production of sperms from the choanocytes and eggs in the mesohyl. Sponges are generally hermaphroditic, but can be only one gender at a time, being either male or female
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Olatubi I.V 1 CLASSIFICATION
1. Class Calcarea: This class consists of members with calcareous spicules occuring in shallow waters. Examples are Caltrina, Schypha, Leucosolenia. 2. Class Hexactinelida: members are the ‘glass sponges’ with siliceous spicules. They consist of a small group in the deep sea; their growth is orientated to the constant water currents there. Their tissues are 75% syncitial (lacking cell boundaries). Even the choanocytes are not separate cells. There are no pinacocytes and no cells with any contractility. The skeleton is a lattice made from six-rayed spicules of silica. Examples are Hyalonema(glass rope sponge), Euplectella (venus flower basket)
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Olatubi I.V 1 CLASSIFICATION CONT’D
3. Class Demospongiae: Some are with siliceous spicules (Examples are Halichondria, the breadcrumb sponge) and others without spicules but only protein fibres (an example is the Spongia, the once commonly used bath sponge).
Venus flower basket bath sponge 5
Olatubi I.V 1 PHYLUM CNIDARIA Characteristics • They are mostly marine except for hydra which is the fresh water form. • They may be sedentary or free swimming. • They are radially symmetrical and their body has two or three layers a gastrovascular cavity and • a single opening that serves as both mouth and anus which is usually surrounded by tentacles. • They possess special stinging cells called cnidocytes or cnidoblasts which helps in food capture defence mechanism and adhesion in the case of sessile cnidarian 6
Olatubi I.V 1 PHYLUM CNIDARIA cont’d • They are carnivorous and exhibit both extracellular digestion i.e. inside the nutritive cells of the endodermis. • process such as respiration and excretion occur by simple diffusion. • The nervous system is primitive and consist of a diffused net of nerve cells. • The soft body of cnidarians may be naked or supported by calcareous exoskeleton or endoskeleton.
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Olatubi I.V 1 PHYLUM CNIDARIA cont’d • Many cnidarians exhibit polymorphism i.e. they exist in 2 different forms • ---a polyp: a tubular body form usually sessile- • ---a medusa: an umbrella shaped free swimming body form. • Polyp represent the asexual phase while the medusa represent the sexual phase of the lifecycle • a polyp give rise to medusa asexually by budding and a medusa produces polyps by sexual reproduction in which fertilized eggs develop into a ciliated free swimming planula larva. This process is termed alternation of generations/metagenesis
8 Olatubi I.V 1 CLASSIFICATION 1. Class Anthozoa • Anemones and most corals belongs to this class members are Polyps with vertical divisions(mesenteries) in the coelenteron. • They have no medusa forms. They are grouped into 2 ---alyconaria: polyps with eight mesenteries and typically eight branched tentacles Examples are Sea pens, Branching corals, Soft corals ---zoantharia: typically with six or twelve mesenteries and variable numbers of simple tentacles Examples are Anemones and True oceanic reef-buildingcorals
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Olatubi I.V 1 CLASSIFICATION CONT’D
2. Class Scyphozoa: • In this class the medusa form is dominant but may develop from a transient polyp-like sessile stage. • Jellyfish are very common in all oceans; they may penetrate shallow seas or be washed ashore. 3. Class Cubozoa: • Their Medusae is with four sides and a marginal shelf • Found in tropical seas, e.g. Australia, where they are known as ‘sea wasps’ and can be poisonous to humans. • They are very different from scyphozoa by having elaborate eyes Examples include Box jellies
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Olatubi I.V 2 CLASSIFICATION CONT’D
4. Class hydrozoa: • Typically with both polyp and medusa stages in the life cycle. • The polyps are small, without mesenteries in the coelenteron, and the medusa may have a shelf Examples are Hydra, Physalia,Obelia, Tubularia • Hydra lives only in fresh water •
Polyp form Medusa forms 1
Olatubi I.V 2 PHYLUM PLATYHELMINTHES D erived from the Greek word platy = flat and helminthes = worms Characteristics • Bilaterally symmetrical. • Body having 3 layers of tissues with organs and organelles. • Body contains no internal cavity. • Possesses a blind gut (i.e. it has a mouth but no anus) • Has Proto-nephridial excretory organs instead of an anus. • Generally dorso-ventrally flattened. • Reproduction mostly sexual as hermaphrodites. • Mostly they feed on animals and other smaller life forms. • Some species occur in all major habitats, including many as parasites of other animals. 2
Olatubi I.V 2 CLASSIFICATION 1 . Class Turbellaria: o Examples are Microstomum,Macrostomum, Mesostoma, Monodiscus Planaria,Notoplana 2. Class Trematoda: o Examples are Gyrodactylus, Aspidogaster, Fasciola, Schistostoma 3. Class Cestoda: o Examples are Phyllobothrium, Echinobothrium, TetrarhynchusT, aenia solium ,Echinococcus, Hymenolepis nana
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Olatubi I.V 2 4
Olatubi I.V 2 PHYLUM NEMATODA De rived From the Greek word Nema = Thread and Eidos = form. Characteristics Bilaterally symmetrical, and vermiform. Body has more than two cell layers, tissues and organs. Body cavity is a pseudocoel, body fluid under high pressure. Body possesses a through gut with a subterminal anus. Has a nervous system with pharyngeal nerve ring. Has no circulatory system (no blood system). Reproduction normally sexual and gonochoristic. Feed on just about everything. Live just about everywhere, many species are endoparasites. 5
Olatubi I.V 2 CLASSIFICATION 1. Class Phasmida/ Secernentia subclass Rhabditia Examples include: (the round worms) ; Ascaris lumbricoides A . suum A. megalocephala (hook worms) ; Ancyclostoma duodenale (pin worms); Enterobius vermicularis subclass spiruria Examples include (Filaria worms) Wuchereria bancrofti Loa loa Onchocerca volvulus subclass Diplogasteria. Example Is (the guinea worm)D racunculus medinensis
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Olatubi I.V 2 CLASSIFICATION cont’d
2. Class Aphasmida/ Adenophorea subclass Enoplia Examples are ( the whip worms); T richuris trichiura Trichinella spiralis subclass chromadoria 7
Olatubi I.V 2 PHYLUM ANNELLIDA De rived From the Latin word Annellus =a little ring. Characteristics Bilaterally symmetrical and vermiform. Body has more than two cell layers, tissues and organs. Body cavity is a true coelom, often divided by internal septa. Body possesses a through gut with mouth and anus. Body possesses 3 separate sections, a prosomium, a trunk and a pygidium. Has a nervous system with an anterior nerve ring, ganglia and a ventral nerve chord. Has a true closed circulatory system. Has no true respiratory organs. Reproduction normally sexual and gonochoristic or hermaphoditic. Feed a wide range of material and live in most environments.
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Olatubi I.V 2 CLASSIFICATION
1. Class Polychaeta (Poly = many, Chaeta = bristle) 2. Class Aelosomata subclass Oligochaeta (Oligo = few, Chaeta =bristle) subclass Branchiobdella subclass Hirundinea (leeches)
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Olatubi I.V 3 PHYLUM ARTHROPODA Derived from a greek word (arthron=joint +podos=foot) characteristics . Possess jointed limbs, fast-contracting striated muscle and a well-developed nervous system. . Possess exoskeleton, which is typically hardened and inflexible over much of the body but remains flexible at joints. . Possess body segments grouped into regions called ‘tagmata’ for example, head, thorax and abdomen.
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Olatubi I.V 3 CHARACTERISTICS cont’d . Most segments bear one pair of appendages: many appendages have been lost in most species.
. The brain, sense organs and nervous system are extremely well developed:
. Their vision relies on various combinations of compound eyes and simple eyes(ocelli): in most species the ocelli can only detect the direction from which light is coming, and the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases can swivel to track prey.
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Olatubi I.V 3 CHARACTERISTICS cont’d . The main body cavity is a haemocoel containing blood, which enters the dorsally placed heart through holes called ostia.
. They also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many setae (bristles) that project through their cuticles.
. They are triploblastic animals with the compound eyes.
. Sexes are usually separate with paired reproductive organs and ducts. . Fertilization is mostly internal. . The eggs are telolecithal (with much yolk). . They either lay eggs (oviparous) or . embryos develop within the female (ovoviviparous). . Asexual reproduction could occur by parthenogenesis in some crustaceans and insects
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Olatubi I.V 3 CLASSIFICATION
The phylum arthropoda is divisible into five(5) subphyla . Trilobithomorpha . Cheliceriformes . Myriapoda . Hexapoda . Crustacea
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Olatubi I.V 3 SUBPHYLUM TRILOBITHOMORPHA
Derived from the Greek word (Tri=three +Lobo=lobes) . Members contain all fossil forms whose body was divided by two longitudinal furrows into 3 lobes.
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Olatubi I.V 3 SUBPHYLUM CHELICERIFORMES
. Members comprises of the sea spiders, horse shoe crab or pseudo scorpion, mite and tick Characteristics . Body is divided into two cephalothorax or prosoma and abdomen or opisthoma. . Cephalothorax bears 6 pairs of appendages including chelicerae, pedipalps and 4 pairs of walking legs. . They have no antennae. . The abdomen consist of twelve segments There are two classes . Class pycnogonida (sea spiders) . Class chelicerata There are two subclasses namely . Merostomata . Arachnida
6 Olatubi I.V 3 MEROSTOMATA & ARACHNIDA
. The subclass merostomata contains the eurypterids which are now extinct and the ancient horse shoe crab. E.g. Limulus polyphemus (restricted to eastern north America) . The subclass arachnida is divided into 11 orders among which are . Araneae e.g. spiders . Scorpiones e.g. scorpions (big black scorpions, small light brown scorpion North African desert scorpions) . Pseudoscopiones e.g. pseudoscopions (American mastigoproctus) . Acari e.g. mites (Sarcoptes scabiei ), ticks (Boophilus decoloratus —blue tick of live stocks in West Africa) . Ricinulei e.g. ricinoides, cryptocellus . Uropygi e.g. uropygians, whip scorpion
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Olatubi I.V 3 SUBPHYLUM MYRIAPODA
. Members are distinguished by a body composed of two tagmata, the cephalon (head) and many segmented trunk. No differentiation into trunk and abdomen . Divided into four classes . chilopoda, . Diplopoda . symphyla . pauropoda Class Chilopoda (centipedes) divided into two subclasses . Subclass notostigomorpha: e.g. Scutigera . Subclass plerostigomorpha: e.g. Lithobius The Class diplopoda (milipedes) divided into 2 subclasses . penicillata . chilognatha
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Olatubi I.V 3
SUBPHYLUM HEXAPODA Characteristics . Members are widely distributed. . Body is differentiated into head thorax and abdomen containing five, three and eleven segments respectively. The head . bears a pair of multi articulate antennae which acts as tactile organ of smell and hearing. . Bears a pair of compound eyes plus 3 simple eyes present in adult.
. posses 3 pair of appendages(mandibles maxillae and labrum) around the mouth. . The mouth is bordered by clypeo-labrum formed by the fusion of labrum and clypeus. . There is a median unpaired tongue like organ called hypopharynx into which salivary gland opens The thorax . Bears the wings and walking appendages . Divided into Pro, Meso and Meta thorax respectively
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Olatubi I.V 3 SUBPHYLUM HEXAPODA cont’d
The subphylum hexapoda is divided into 2 classes Class Entognatha(with 3 orders) • Order Protura • Order diplura • Order collembola Class Insecta Ectognathous because mouthparts is exposed and projecting from head capsule. Comprise 3 subclasses
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Olatubi I.V 4 CLASS INSECTA
1. Subclass Archaeognata: jumping bristles small wingless with scaly body, large compound eyes. 2. Subclass Zygentoma: a single order ‘thysanura’ e.g. silverfish. 3. Subclass Pterygota (winged insects) . Infra class Palaeoptera (with 2 orders) . Order Epheromeptera e.g mayflies. . Order odonata e.g. dragonflies and damselflies . Infraclass Neoptera (with 26 orders)
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Olatubi I.V 4 INFRACLASS NEOPTERA
. Modern wing folding insects comprising of 26 orders among which are: . Order Blattodea e.g. cockroaches. . Order Mantodea e.g. praying mantids. . Order Orthoptera e.g. grasshoppers, locusts. . Order Isoptera e.g. white ants termites. . Order Phthiraptera e.g. sucking and biting lice. . Order Anoplura e.g true sucking lice. . Order Mallophaga e.g. biting lice. . Order Hemiptera e.g. true bugs. . Order Coleoptera e.g. beetles. . Order Lepidoptera e.g. butterflies, moths. . Order Hymenoptera e.g. ants, bees, wasp. . Order Diptera e.g. true flies, mosquitoes. . Order Siphonaptera e.g. fleas
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Olatubi I.V 4 3
Olatubi I.V 4 SUBPHYLUM CRUSTACEAN . Characteristics . They are aquatic mandibulates. . Their 2nd and 3rd segments bears a pair of antennae. . 60 segments or more in the lower crustaceans with 20 in higher forms. . Body is divided into the head(cephalon), trunk ( of more than 65 segments) and abdomen(of numerous segments) . The 1st segment fuses with the head to form a cephalothorax. . The head Bears 5 pairs of appendages; 1st antennae, 2nd antennae, mandibles, 1st maxillae and 2nd maxillae . The abdominal segment terminates in a telson bearing the anus. . They often possess a cephalic shield called carapace. . Most possess a pair of well-developed compound eyes while some have simple ocelli 4
Olatubi I.V 4 SUBPHYLUM CRUSTACEAN cont’d . Gaseous exchange is by gills. . But by body surface in lower crustaceans . Circulation is open, with their blood being haemolymph. . Their respiratory pigment is haemocyanin. . Main excretory organ in adult is a pair of tubular structures located in the ventral part of the head. . Sexual Reproduction usually occurs in crustaceans but parthenogenesis is common among many brachiopods and certain ostracods CLASSIFICATION 1. Class Remipedia: only one living order “Nectiopoda” eyes are absent in this order. E.g. Speleonectes and Lasionectes 2. Class Cephalocrida; They are true hermaphrodites as they discharge both eggs and sperm from the same duct that opens on the 9th segment. E.gH. utchinsoniella 5
Olatubi I.V 4 SUBPHYLUM CRUSTACEAN CONT’D
3. Class Branchiopoda; This class is divided into 3 orders
. Anostraca (fairy shrimps): without carapace found in hyper saline lake and marine lagoon e.gA rtemia (brine shrimp). . Notostraca: Possess broad carapace and narrow trunk giving the animal a tadpole appearance. Hence the name tadpole shrimp. E.g. Triops and lepidurus. . Diplostraca. Have large carapace that encloses the entire head. This order has 4 sub orders among which are laevicaudata (clam shrimps), cladocera (water fleas) 4. Class Maxilopoda; There are 7 subclasses in this group . Theocostraca (barnacles). . Tantulocarida (deep water marine parasites). . Branchiura (fish lice). . Pentastomida (tongue worms). . Mystacocarida (mystacocarids). . Copepoda (copepods). . Ostracoda (ostracods)
6 Olatubi I.V 4 SUBPHYLUM CRUSTACEAN cont’d Class Malacostraca; the largest class with members such as lobsters, crabs, shrimps, beach hoppers etc. There are two subclasses . Subclass phyllocarida: only one order ‘Leptostraca’ e.g.N ebalia bipes . . Subclass Eumalacostraca: 4 super order; . Super order Hoplocarida e.g. Squilla mantis . . Super order Syncarida e.g. Bathynella natans the blind European cave dweller. . Super order Eucarida; 3 orders namely Euphausiacea, Amphiniodacea and Decapoda. . Super order Peracarida; has 9 orders namely Mysida, Lophogastrida, Cumacea, Tanaidacea, Mictacea, Spelaeogriphacea, Thermosbaenacea, Isopoda, Amphipoda
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Olatubi I.V 4 PHYLUM MOLLUSCA
Derived from latin word Mollis=soft. Members have tremendous morphological diversity. They posses well calcified skeleton that have easily recognized features. These features are Mantle A fold which encloses a significant amount of space and lined by the epidermis. In it lies the anus, a pair of osphradia (chemical sensors), a pair of gills, exit openings of the nephridia and gonads (reproductive organs) Shell The mantle edge secretes a shell that consists of mainly chitin and conchiolin (a protein hardened with calcium carbonate). The shell consists of three layers: the outer layer made of organic matter, a middle layer made of columnar calcite, and an inner layer consisting of laminated calcite Foot The underside of the Mollusc which has adapted to different purposes in different classes. The foot carries a pair of statocysts, which act as balance sensors.
8 Olatubi I.V 4 CHARACTERISTICS The phylum has exploited a wide variety of environment ranging from terrestrial forest to fresh water lakes down to the deepest part of the ocean Respiration is by one –many ctenidia(gills),secondary gills, air breathing lungs. Excretion is by large tubular metanephridia(kidneys). The central nervous system of majority is composed of a nerve ring around the oesophagus formed by 3 pair of large ganglia(cerebral,pleura, pedal) that interconnect with each other. Sexes are separate in most species although many are hermaphrodites. Fertilization is either internal or external. The have distinct head bearing the mouth and with eyes, tentacle and other sense organs except in Pelecypoda and Scaphoda. They have simple digestive tract consisting of an anterior mouth with a posterior anus but in the gastropods scophopods and cephalopods the intestine become u shaped bringing the anus to an anterior position. They have an open circulation except in cephalopods. They posses pharynx which contains a rasping organ called radula except in the pelecypoda.
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Olatubi I.V 4 CLASSIFICATION Grouped into eight classes namely: Monoplacophora; example include Neopilina. Polyplacophora; example include Chiton. Scaphopoda; examples elephant tusk shells, tooth shells. Chaetodermomorpha; examples include chaetoderma, crystalloprisson Neomemomorpha; examples include neomania Gastropoda; examples include snails limpets, slugs whelks, conchs,periwinkles,seaslugs, seahares, sea butterflies. Pelecypoda (bivalvia); examples are mussels, clams, scallops,oysters and ship worms. Cephalopoda; examples include squids,octopus,nautili, cuttlefishes
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Olatubi I.V 5 Tonicella lineata , a Cornu aspersum –a common polyplacophoran or chiton, land snail diagram of a typical ancestral mollusc 1
Olatubi I.V 5 PHYLUM ECHINODERMATA
Derived from the ancient Greek word Echinos=hedgehog/spiny, and derma=skin. Characteristics They are closely related to chordates in that one group (the cinctans) have been found to posses external gills used for filter feeding like in the chordates and hemichordates.
Exclusively marine: posses water vascular system.
Possess project spine/tubercules that gives the animal a rough/ spiny appearance.
They have triploblastic coelomic body.
Adults are radially symmetrical but larvae are bilaterally symmetrical
2 Olatubi I.V 5 PHYLUM ECHINODERMATA cont’d
Body surface is with spines consisting of 5 radiating areas called Ambularia.
They have simple and complete alimentary canal.
Circulatory system is reduced.
Respiration is by minute gills (Papullae) protruding from the coelom.
Posses no special excretory organs.
Nervous system is simple and consist of Circumoral ring.
Sense organs are poorly developed.
Sexes are separate and fertilization is external
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Olatubi I.V 5 CLASSIFICATION 1. Crinoidea: examples are sea lilies, feather stars 2. Asteroidea: an example include the starfish 3. Echinoidea: examples are sea urchins, heart urchins sand dollars sea biscuits lamp urchins 4. Ophiuroidea: examples include brittle stars snake stars 5. Holothuroidea: examples sea cucumbers
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Olatubi I.V 5 A star fish Various forms of Echinoderms 5
Olatubi I.V 5 PHYLUM CHORDATA The phylum Chordata accounts for all species of vertebrates on earth and several other species of invertebrates. Members share 4 diagnostic feature 1. Notochord: A structure that runs through the digestive system and its nerve chord. In most vertebrate the skeleton develops around them and allows the muscles to attach. In humans the notochord is reduced to cartilage that is found between the vertebra 2. Dorsal hollow nerve chord: A tube nerve fibre that develops into the central nervous system (CNS) 3. Pharygeal slits: In the lancelates they function as filters for feeding. In fishes and other aquatic vertebrates they are gill-slits but In terrestrial vertebrate (e.g. man) they disappear before they are born. They are the tissues that develop into areas around the jaws, ear, neck 4. Post anal tail: It helps propel animals in water. 6
Olatubi I.V In humans it shrinks during embryonic development 5 CLASSIFICATION 1. Subphylum Urochordata/tunicata 2. ,,, Cephalochordata 3. ,,, Vertebrata Urochordata Invertebrate chordates. Exclusively marine. Notochord is present only in larval tail. Examples are ascidia, salpa and doliolum Cephalochordata Notochord extends from head to tail region and persistent throughout life. Examples are branchiostoma (amphioxus /lancelets) 7
Olatubi I.V 5 CLASSIFICATION cont’d Vertebrata They possess notochord during the embryonic period the notochord is replaced by a cartilaginous or bony vertebral column in the adult. Have two image forming eyes. Have a well developed closed circulatory system with ventral muscular heart having two three or four chambers. Possess kidneys for excretion and osmoregulation. Possess paired appendages which may be fins or limbs. Have centralized nervous system ,digestive system is complete with 2 large digestive glands the liver and pancreas. Coelom is large and well developed and filled with internal organs 8
Olatubi I.V 5 CLASSIFICATION cont’d
The subphylum vertebrata is divided into 2 super classes Superclass Agnatha Class Myxini Class Cephalospidomorphi Superclass Gnathostomata Class Pisces Class Amphibia Class Reptilia Class Aves Class Mammalia
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Olatubi I.V 5 CLASSIFICATION cont’d
PISCES Members are aquatic. Possess fins and gills. Cold blooded Classified into Chondrichthyes (cartilagenous fishes like sharks rays and fins). Osteichthyes (bony fishes like perch tuna catfish blue gill ) AMPHIBIAN Posses four limbs. Cold blooded. Have both aquatic and terrestrial stages in their cycles. Skin is moist and susceptible to desiccation. Limbs usually have 5 fingers aquatic larval forms usually breath by gills that are lost during metamorphosis d adult breathe by lungs Examples are frogs, toads, and salamander
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Olatubi I.V 6 Clockwise from top right:S eymouria , Mexican burrowing caecilian, eastern newt and leaf green tree frog 1
Olatubi I.V 6 CLASSIFICATION cont’d
REPTILIA Have dry scaly skin that is not normally susceptible to desiccation breath by lungs Examples include turtles lizards snakes crocodiles alligators AVES Warm blooded. Fore limbs are modified into wings. Body covered with feathers Example includes all the birds MAMMALIA Members are warm blooded. Young are nourished after birth by secretions of the mammary glands of the mother. Body normally covered by hair at some stage of their existence Examples are squirrels, bats, monkeys and man
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Olatubi I.V 6 REFERENCES
• Invertebrate Zoology by Jordan E.L. and P. S., Verma New Delhi,: S. Chand and Company Pvt. Ltd., 2011. • TROPICAL ZOOLOGY (2013) by Ademola Segun. • An Introduction to the Invertebrates by Janet Moore New Hall, Cambridge University Press 2006. • https//. Wikipedia • PRACTICAL ZOOLOGY VERTEBRATE by S. S. LAL CAPITAL OFFSET PRESS, 2009-2010. • Examples of Animals in the Subphylum Urochordata By Amy S. Jorgensen. • Googgle images 3
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