Chapter 11

1. Chapter 11 Fishes, Amphibians, Reptiles

2. Section 1: What is a Vertebrate? • Characteristics of CHORDATES • Most are Vertebrates (have a backbone) • Some point in life cycle all chordates have: • Notochord • Nerve cord that runs down their back (like a spinal cord) • Slits in their throat area

3. NOTOCHORD • Flexible rod that supports a chordate’s back • Lancelet has a notochord its whole life • All vertebrates have part or all of notochord replaced with a backbone • SLITS in Throat Area • Also called Pharyngeal slits (or gill slits) • Fish have them their whole life • In humans, they disappear before birth

4. Characteristics of Vertebrates • Makes up most chordates • Has backbone that is part of an internal skeleton • Backbone = spine • Formed by bones called vertebrae • Joints in between each bone provide flexibility • Hole through each vertebrae for spinal cord • Makes up part of endoskeleton • Protects internal organs • Gives body its shape • Does not need to be replaced • Location for muscle attachment • Allows greater growth

5. Embryonic Development of Vertebrates

6. Keeping Conditions Stable • Ectotherms • Fish, reptiles, amphibians • Animal whose body does not produce much internal heat • Body temperature changes based on temperature of the surrounding environment • Endotherms • Birds and mammals • Animals that regulate their own body temperature • Adaptations including sweat glands, fur/feathers • Larger variety of suitable living environments

7. Section 2: Fishes • Aquatic vertebrate with fins • Most are ectotherms (some sharks and tuna are endothermic!) • Obtain oxygen through gills • Have scales • Largest group of vertebrates • Three major groups: • Jawless • Cartilaginous • Bony

8. Obtaining Oxygen • Fish opens its mouth and take a gulp of water • Water moves through throat and then to gills • Gills contain many blood vessels • Oxygen diffuses into blood vessels • Carbon dioxide diffuses out • Water flows out of slits beneath the gills

9. Circulatory System • Oxygen-rich blood travels through closed system • Two-chamber heart • Pumps blood in one loop • Heart  gills  rest of body  back to heart

10. Reproduction • External fertilization • Eggs fertilized outside of female’s body • Male hovers close to female • Male spreads a cloud of sperm cells over released eggs • Young develops outside of female’s body • Internal fertilization- some sharks, guppies, skates • Eggs fertilized inside of female • Female gives birth to offspring

11. Jawless Fish • No jaws and no scales • Mouths designed for scraping, stabbing, and sucking their food • Hagfishes- scavengers w/ large, slimy worm-like bodies • Lampreys- Parasites of other fish

12. Cartilaginous Fish • Skeletons made of cartilage • Have jaws and scales • Sharks, rays, skates • Usually carnivores • Rays and skates- hunt on ocean floor for mollusks, crustaceans, and small fish • Sharks- attack and eat anything that smells like food • Used jagged teeth arranged in rows • Only front teeth are used for feeding • Teeth move forward if front teeth are lost

13. Bony Fishes • 95% of all fish • Trout, tuna, goldfish • Skelton made of hard bones • Scales and a jaw • Pocket on each side of the head that hold the gills • Swim bladder • Internal, gas-filled sac • Helps stabilize fish at different depths

14. Section 3: Amphibians • Means “double life” • Beginning of life in water, adult life on land • Return to water to reproduce • Ectothermic vertebrate • Two groups: • Salamanders- keep tails in adulthood • Frogs and toads- no tail in adulthood

15. Reproduction and Development

16. Living on Land • When amphibians become adults, multiple adaptations occur: • Lose gills and develop lungs for gas exchange • Circulatory system changes from single loop with a 2-chamber heart to two loops with a 3-chamber heart • Atria- two upper chambers • Left gets blood from lungs • Right gets blood from body • Ventricle- lower chamber • pumps blood out to both lungs and body

17. More Adaptations • Change from herbivores to carnivores • Develop camouflage to help obtain food • Develop skeletons and muscular limbs • Powerful hind-leg muscles for jumping • Skelton to absorb shock when landing • Changes to the feet • Webs to aid in swimming • Sticky pads for climbing

18. Indicator Species • An organism whose presence, absence or abundance reflects a specific environmental condition. -an appealing research and monitoring tool.

19. Section 4: Reptiles • Ectothermic vertebrates with lungs and scaly skins • Snakes, lizards, turtles, alligators • Can spend entire life on land • Adaptations for water conservation: • Dry, tough skin with scales • Kidneys filter wastes which are excreting as urine • Amniotic egg prevents embryo from drying out

20. Amniotic Egg • Reptiles exhibit internal fertilization • Lay eggs on land • Egg contain shell and 4 internal membranes • Shell has pores for gas exchange • 4 Membranes for: • Holding liquid that surrounds embryo • Holding yolk (food for embryo) • Holding embryo’s wastes • Exchange of O2 and CO2

21. Lizards • Skin with overlapping scales • Shed their skin and scales as they grow • 4 legs with claws on toes • Long tails, external ears, movable eyelids, two lungs • Carnivores that jump at their prey • Eat frogs, birds, insects depending on size

22. Snakes • Identical skin qualities as lizards • No legs, streamlined bodies, no external ears or eyelids • Most have only one lung • Eat small animals like mice • Use long front teeth for hooking • Some inject venom via their fangs • Jawbones can spread apart • Skull bones can move to swallow large prey

23. Alligators and Crocodiles • Largest living reptiles • Take care of their young • Carnivores that hunt at night • Hunting/Eating adaptations include: • Strong, muscular tails fro swimming • Jaws with large, sharp, pointed teeth • Strong jaw muscles for biting down

24. Alligator and Crocodile Reproduction • Care for eggs and newly hatched young • Female stays near the nest • Periodically, she will crawl over nest from the water to keep it moist • Once eggs hatch, mother will scoop them up in her mouth and carry them away to a safe area in the water • May stay with young up until a year or when they can feed and protect themselves

25. Turtles • Reptile covered by protective shell w/ ribs and a backbone • Shells are either hard or soft • Some can bring head, legs, tail inside for protection • Tortoises = land turtles • Have sharp-edged beak instead of teeth for eating • Can be carnivores or herbivores

26. Extinct Reptiles- Dinosaurs • Ancestors of reptiles • Extinct 65 million years ago • Some may have been endothermic • Herbivores walked on 4 legs • Carnivores walked on 2 legs

27. Section 5: Vertebrates History in Rocks • What are Fossils? • Hardened remains of living things • Bones, shells, skeletons • Tissues are replaced by hard minerals • Found in sedimentary rocks • Layered rocks containing particles of: • Clay • Sand • Mud • Silt

28. More on Fossils • Paleontologist = scientists who study extinct organisms by: • Examining fossil structures • Making comparisons to present-day organisms • Can determine approximate age by: • Studying sediment layers • Examining radioactive decay

29. Vertebrate Evolution • Fish- 530 million years ago • Amphibians- 380 million • Reptiles- 320 million • Mammals- 220 million • Birds- 150 million • Birds and Mammals are both descendants of reptiles