Chapter 29, 33.3: Vertebrate Animals and Homeostasis Key Concepts

Home , Endostyle, Spotted moray, Spotted moray eel

Major Diversity of Characteristics Homeostasis Vertebrates of Chordates

Chordates comprise all vertebrates (~60,000 species) and two groups of invertebrates, the urochordates and cephalochordates All chordates share 5 characteristics…

Endostyle

*Some species have traits only during embryonic development All chordates share 5 characteristics…

Endostyle

Notocord= longitudinal, flexible rod between the digestive tube and nerve cord, provides skeletal support

#2 #1

Endostyle

Nerve Cord= develops into the central nervous system: brain & spinal cord

#2 #1

Endostyle #3

Pharyngeal Slits/Clefts: grooves form along outer surface of pharynx Suspension-feeding structures, gas exchange structures, or parts of ear and neck in tetrapods

#2 #4 #1

Endostyle #3

Muscular Post-Anal Tail: contains skeletal elements and muscles In many species, the tail is greatly reduced during embryonic development

#2 #4 #1

#5 Endostyle #3

The endostyle is a strip of ciliated mucus-producing tissue in the floor of the pharynx= food particles trapped in the mucus are moved along the endostyle toward the gut. Also produces substances similar to thyroid hormones and is homologous with the thyroid gland in vertebrates. © 2017 Pearson Education, Inc. Lancelets (Cephalochordata) named for bladelike shape • Marine suspension feeders • Retain characteristics of chordate body

plan as adults 1 cm 1

Cirri

Mouth Notochord Pharyngeal slits Dorsal, hollow nerve cord Atrium Digestive tract Ancestral chordates may have Atriopore resembled lancelets: Segmental same Hox genes organize the muscles Anus vertebrate brain are expressed in lancelet’s nerve cord tip Tail © 2017 Pearson Education, Inc. Tunicates (Urochordata): more closely related to other chordates than lancelets • resemble chordates during larval stage, may last only a few minutes for some species

Incurrent Water flow Notochord siphon to mouth Excurrent Dorsal, hollow siphon nerve cord Tail Excurrent Excurrent siphon siphon Atrium Muscle Incurrent segments siphon Pharynx Intestine with numerous Anus Stomach slits Intestine Atrium Tunic Esophagus Pharynx with slits Stomach (a) A tunicate larva (b) An adult tunicate (c) An adult tunicate Vertebrates are chordates with a backbone

▪ 2+ sets of Hox genes ▪ lancelets and tunicates have only one ▪ Most vertebrates- vertebrae enclose spinal cord and taken role of notochord ▪ Neural crest- cells develop along edge of neural tube of an embryo, develop into nerves, cardiovascular tissue, facial structures ▪ Skeletal system and complex nervous system increased effectiveness of… ▪ Capturing food ▪ Evading predators SuperclassFigure 34.8 Agnatha: Earliest vertebrates did not have jaws • 2 jawless vertebrate lineages today: Myxini: hagfishes & Petromyzontida: lampreys • Lack a true backbone • Rudimentary vertebrae & phylogenetic analysis support them as vertebrates

Hagfishes: marine; most bottom-dwelling Lampreys: marine & freshwater habitats scavengers • Parasites- feed by clamping mouths onto a live fish • produce slime to repel competitors and • Free-living species- feed as larvae for years, then predators mature, reproduce, and die within a few days

Slime Parasite Mouth glands

© 2017 Pearson Education, Inc. Gnathostomes are vertebrates with jaws ▪ Earliest gnathostomes ~440 mya ▪ Fins developed bony structures, provided thrust & steering control for pursuit of prey & avoidance of predators • Characters common to gnathostomes: • Genome duplication, including duplication of Hox genes • Enlarged forebrain associated with enhanced senses of smell and vision • Lateral line system: rows of organs sensitive to vibrations along each side of body of aquatic gnathostomes • Today, gnathostomes, include sharks, fishes, amphibians, reptiles, birds, & mammals

Dorsal fins group includes the sharks, rays, and skates • Second group has few dozen species of Pelvic fins Pectoral fins ratfishes

(a) Blacktip reef shark (Carcharhinus melanopterus)

(b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei)

© 2017 Pearson Education, Inc. Figure 34.17 Majority of vertebrates are osteichthyans: animals with a bony endoskeleton Ray-finned fishes ~30,000 species Yellowfin tuna (Thunnus albacares) (Actinopterygii) include Red lionfish (Pterois nearly all familiar aquatic volitans) osteichthyans

The fins, supported mainly by long, flexible rays, are modified for maneuvering, defense, and other functions

Common sea horse Fine-spotted moray eel (Hippocampus (Gymnothorax dovii) ramulosus) Majority vertebrates are osteichthyans: animals with bony endoskeleton Lobe-Fins (Sarcopterygii): 3 living lineages ▪ Coelacanths (Actinistia): thought to be extinct until a living coelacanth was caught on coast of South Africa in 1938 ▪ Lungfishes (Dipnoi): found in Southern Hemisphere ▪ Gills are main organs for gas exchange, also surface to gulp air into lungs ▪ Tetrapods: group adapted to life on land

▪ Adaptations ▪ Four limbs and feet with digits ▪ Neck: allows separate movement of head ▪ Fusion of pelvic girdle to backbone ▪ Absence of gills ▪ except some aquatic species ▪ Ears for detecting airborne sounds

(a) Order Urodela

Frogs (Anura): lack tails • Aquatic and terrestrial

(b) Order Anura

Caecilians (Apoda): legless, nearly blind • Absence of legs is secondary adaptation

(a) The tadpole (b) During metamorphosis

Amphibian means “both ways of life,” referring to the metamorphosis of an aquatic larva into a terrestrial adult Larval stage of a frog= aquatic herbivore with gills, lateral line, tail During metamorphosis= develops legs, lungs, a pair of external eardrums, and a carnivorous digestive system

(c) The adults return to water to mate Amniotes are Extraembryonic membranes tetrapods that have a Allantois Chorion terrestrially adapted egg Embryo Reptiles, Birds, Amniotic cavity Mammals with amniotic fluid

Yolk (nutrients)

Amnion= encloses embryo in fluid-filled sac, Albumen allows tetrapods to reproduce on Shell land Amnion Yolk sac Extraembryonic membranes (a) Tuatara (Sphenodon punctatus) Adaptations for Terrestrial Life Reptiles • Scales create a waterproof barrier • Shelled eggs • Internal fertilization

Most reptiles are ectothermic

(d) Black-breasted hill turtle (Geomyda spengleri) (e) American alligator (Alligator mississippiensis) Evolution of Birds Wing claw (~160 mya) Toothed beak

Archaeopteryx: oldest bird known

Had feathered wings, but retained ancestral reptile characters: teeth, claws, long tail

Airfoil wing with contour feathers Long tail with many vertebrae Derived Characters of Birds ▪ Endothermic ▪ Adaptations for flight: ▪ Wings with keratin feathers ▪ Improved vision ▪ Fine muscle control ▪ Weight-saving adaptations: ▪ Loss of bladder ▪ One ovary in females ▪ Small gonads ▪ Loss of teeth ▪ Flight benefits: improved hunting & scavenging, escape from predators, and migration ▪ But..requires great expenditure of energy Not all birds fly… Bird Reproduction ▪ Birds generally display complex behaviors including elaborate courtship rituals ▪ Fertilization is internal ▪ Eggs and the developing embryos inside must be kept warm through brooding by one or both parents Mammals are amniotes that have hair Monotremes and produce milk Derived Characters of Mammals ▪ Mammary glands ▪ Endothermy ▪ Hair and a fat layer under skin Marsupials ▪ Kidneys ▪ Efficient respiratory and circulatory systems ▪ Large brain-to-body-size ratio ▪ Extensive parental care Eutherians ▪ Differentiated teeth

Platypus Echidnas

© 2017 Pearson Education, Inc. Marsupials Embryo develops in mother’s uterus, nourished by placenta Offspring born early in development, completes development while nursing in a maternal pouch called a marsupium

New World monkeys Anthropoids

Old World monkeys

Gibbons Orangutans Derived Characters of Primates • Hands and feet adapted for grasping, flat Gorillas nails instead of claws Chimpanzees • Large brain, short jaws and bonobos • Forward-looking eyes close together on the †Australopithecus face, providing depth perception Humans and • Fully opposable thumb (monkeys, apes) extinct Homo species 70 60 50 40 30 20 10 0 Time (millions of years ago) Monkeys (a) New World monkey: spider monkey Found in central and south America

(b) Old world monkey: macaque Found in Asia and Africa Non-human Apes (a) Gibbon (b) Orangutan

(d) Chimpanzee (e) Bonobo

▪ Human & chimpanzee genomes are 99% identical ▪ differ in expression of 19 regulatory genes ▪ Derived Characters of Humans ▪ Upright posture and bipedal locomotion ▪ Larger brains capable of language, symbolic thought, artistic expression, and the manufacture and use of complex tools ▪ Reduced jawbones and jaw muscles ▪ Shorter digestive tract Figure 34.47 Hominin species large-brain, bipedal Paranthropus Homo Homo Homo robustus ergaster neanderthalensis sapiens 0 ? Paranthropus 0.5 boisei

1.0

1.5 Australopithecus africanus 2.0 Kenyanthropus 2.5 platyops Australopithecus 3.0 garhi Homo erectus Australopithecus 3.5 migrate out anamensis Homo Homo rudolfensis of Africa

4.0 habilis Millions of years ago 4.5 Tool use Australopithecus afarensis 5.0 walked fully erect Ardipithecus ramidus 5.5

6.0 Orrorin tugenensis

6.5 Sahelanthropus 7.0 tchadensis Neanderthals ▪ Homo neanderthalensis, lived in Europe & Near East beginning ~350,000 years ago ▪ thick-boned with a larger brain than modern humans ▪ buried their dead, made hunting tools ▪ Lineages leading to H. sapiens and H. neanderthalensis diverged about 400,000 years ago ▪ Genetic analysis indicates gene flow occurred between Neanderthals and Homo sapiens ▪ Modern-day humans of European descent have 1%-4% of Neanderthal DNA Homo sapiens ▪ Oldest documented fossils of Homo sapiens found at 2 sites in Ethiopia, specimens are 195,000 and 160,000 years old ▪ Oldest fossils of Homo sapiens outside Africa ~115,000 years old , from Middle East ▪ Humans first arrived in the New World sometime before 15,000 years ago Feedback control maintains the internal environment in many animals

▪ Two environments important to an organism ▪ External environment surrounding organism ▪ Internal environment where cells live ▪ Internal Exchange ▪ Movement of water and materials into cells Hydra ▪ Interstitial Fluid: fluid surrounding cells ▪ exchange of water and materials between blood and body cells goes through interstitial fluid ▪ External Exchange ▪ Take in oxygen, water, and food ▪ Release carbon dioxide, urine, feces, heat, sweat Whale Shark Feedback control maintains the internal environment in many animals ▪ Faced with environmental fluctuations, animals manage their internal environment by either regulating or conforming ▪ Regulator uses internal control mechanisms to control internal change in the face of external fluctuation ▪ Conformer allows its internal condition to vary with certain external changes ▪ Animals may regulate some environmental variables while conforming to others Adaptation: Branches or Folded Surfaces

▪ Many internal structures have large number of branches or folds ▪ Increases surface area for exchange in minimal amount of space Regulation of Internal Environment

▪ Homeostasis= “steady state” ▪ Temperature ▪ pH ▪ Water Balance ▪ Oxygen Regulation of Internal Environment

▪ Homeostasis= “steady state” ▪ Temperature ▪ pH ▪ Water Balance ▪ Oxygen ▪ Set points and normal ranges can change with… ▪ age ▪ day/season ▪ external environment ▪ acclimatization is a temporary change during an animal’s lifetime ▪ Involves coordinated actions of multiple systems Negative Feedback Loops

▪ A change in a “variable” signals a mechanism to reverse the change ▪ Home thermostat uses negative feedback ▪ Human body regulates temperature at 37°C ▪ Hypothermia= less than 35°C (Fatal= less than 28°C) ▪ Hyperthermia= above 37.5°C (Fatal= above 40°C) Thermoregulation of Humans: Negative Feedback Loop

NORMAL BLOOD pH (about 7.4) Blood CO2 level falls and pH rises. Blood pH falls due to rising levels of CO2 in tissues (such as Medulla detects when exercising). decrease in pH of cerebrospinal fluid.

Cerebrospinal fluid Carotid arteries Aorta Signals from Sensors in major medulla to rib blood vessels muscles and detect decrease diaphragm in blood pH. increase rate Medulla Medulla receives and depth of oblongata signals from major ventilation. blood vessels.

Nerve Axon • Nervous system • Endocrine impulse Hormone transmits system releases Signal travels Signal travels everywhere. to a specific signaling molecules location. information called hormones between specific

Blood into the Nerve locations vessel bloodstream impulse Axons • Transmission is • Relatively slow fast acting, but can have long-lasting

Response effects Response Thermoregulation: Temperature Control Endotherms primarily rely on internal heat generation ▪ maintain internal body temperature different than the environment ▪ Higher energetic costs to animal ▪ Birds, mammals, some fish, shark, and insect species Thermoregulation: Temperature Control Ectotherms ▪ regulate body temperature mainly through energy exchange with external environment ▪ generally have greater tolerance for variation in body temp than endotherms *majority of animal species Variation in Temperature (7)

• Conduction—transfer of energy from warmer to cooler molecules. Energy • Convection—heat energy is carried by exchange moving water or air. with the • Latent heat transfer—water absorbs heat as it changes from liquid to gas environment: state. • Radiation from the sun Mechanisms of Thermoregulation

Body Size ▪ Mammals- increase in size from equator to poles ▪ Larger animals= lower surface area to volume ratio ▪ Decreases heat loss ▪ Smaller animals= higher surface area to volume ratio ▪ Increases heat loss Mechanisms of Thermoregulation

▪ Evaporative Cooling ▪ Circulatory Adaptations to Increase/Decrease Heat Loss ▪ Insulation ▪ Metabolic Heat Production ▪ Heat produced as by- product of cellular respiration ▪ Hormones increase metabolic rate in winter ▪ Shivering creates muscle contractions Mechanisms of Thermoregulation

▪ Behavioral Responses ▪ Migration ▪ Sunbathing ▪ Burrowing ▪ Swimming ▪ Huddling ▪ Torpor/Hibernation Don’t Forget…

Answer the True/False Question for Module 10 Participation Quiz

Quiz 7 due Monday, November 9th