1. Fish, Amphibians, & Reptiles

2. Ectotherms
Most vertebrates are ectotherms (animals whose internal body temperature changes with the temperature of its surroundings).
Some ectotherms:
Fish
Amphibians
Reptiles

3. FISH
Ectotherms
To breathe a fish takes in water through its mouth and over its gills- oxygen is taken up by blood vessels and carbon dioxide is released.

4. Fins
Fish have fins for steering, balancing, and moving. The large tail fin moves back and forth to propel the fish through the water.

5. Gill Slits
Gill slits are paired openings located in the throat behind the mouth. Develop into gills in fish. Traces of gills can be seen in embryos of many vertebrates (even humans).

6. Endoskeleton
The endoskeleton is made up of the vertebrate, the skull, and the rest of the internal skeleton.

7. Scales
Fish also have scales that protect the fish’s body. Most fish scales are made of bone.

8. The Three Classes of Fish
Fish are grouped into three classes:
1) jawless fish
2) cartilaginous fish
3) bony fish
Hagfish, juvenile tiger shark, lionfish

9. Jawless Fish Class: Agnatha which is Greek for “jawless” Round mouths
Long, tubelike bodies
Bodies covered with slimy skin (no scales!)
skeletons made of cartilage (tough, flexible tissue that is not as hard as bone)
Examples:
Lamprey
Hagfish

10. Cartilaginous Fish
Class: Chondrichthyes (means “cartilage” and “fish”)
Skeletons made of cartilage
Movable jaws
Scales
Examples:
Sharks
Skates
Rays

11. Bony Fish Class: Osteichthyes (means “bones”) Skeletons made of bone
95% of all species of fish belong to this class
Reproduce by external fertilization (spawning)

12. Buoyancy
Most bony fish have a swim bladder (an air sac that helps control the buoyancy of the fish). The swim bladder allows the fish to adjust its density so it can rise or sink.

13. Kinds of Bony Fish Bony fish are organized into three groups:
Lobe-finned fish
Lungfish
Ray-finned fish
Lungfish (fisherman), rayfinned (orange), lobe-finned fish (bottom right)

14. Lobe-finned Fish
Lobe-finned fish have fins that are lobe-like and fleshy. Scientists think fish like these were the ancestors of the first land vertebrates.

15. Lungfish
Lungfish have both gills and lungs for breathing. This allows the lungfish to live in shallow waters that dry up in the summer. They simply burrow into the mud and cover themselves with mucus until the waters return.

16. Ray-finned Fish
Ray-finned fish have fins made of long, thin bones covered with skin.
Atlantic Salmon

17. Amphibians Ectothermic vertebrates
Spend part of life in water and part on land
Examples:
Frog
Toad
Salamander
Newt

18. Hibernation
In the winter amphibians will hibernate. Some will also become inactive during the hot, dry summer months (estivation).
Most amphibians return to water to lay their eggs

19. Frogs Have a sticky saliva on their tongue to help pull in insects
Behind their eyes, frogs have round tympanic membranes that vibrate in response to sound

20. Toads
Toads breed in water, but they spend the rest of their time in woods or other moist environments.
They have thick, warty skin
Many have glands on their backs that secrete poison.

21. Salamanders and Newts
Salamanders and newts have legs that stick straight out from the sides of their bodies
At night they feed on worms, crustaceans, and insects

22. Metamorphosis
Frogs undergo a series of changes from egg to adult.

23. Reptiles Ectothermic vertebrate with dry, scaly skin Examples: Lizards
Snakes
Turtles
Crocodiles
Alligators

24. Characteristics Reptiles breathe with lungs
Eggs of reptiles are fertilized internally. The female secretes a leathery shell around each egg and then lays the eggs on land

25. Turtles
Turtles have a hard shell on both top and bottom that they will withdraw into for protection
Turtles eat insects, worms, fish, and plants

26. Crocodiles and Alligators
Found in or near water in tropical climates
Crocs have long, slender snouts and are aggressive- alligators are less aggressive

27. Lizards and Snakes Make up the largest group of reptiles
Lizards feed on reptiles, insects, spiders, worms, and mammals
Snakes are meat-eaters. Some constrict their prey. Others inject their prey with venom.