Fish, Amphibians, & Reptiles

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

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.

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

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).

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

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

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

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

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

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)

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.

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)

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.

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.

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

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

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

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

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.

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

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

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

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

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

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

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.