AMPHIBIANS & REPTILES ARE ADAPTED FOR LIFE ON LAND VERTEBRATES ADAPTED TO LIVE ON LAND. AMPHIBIANS HAVE MOIST SKIN & LAY EGGS WITHOUT SHELLS. REPTILES HAVE DRY, SCALY SKIN & LAY EGGS WITH SHELLS. BODY TEMPERATURES OF AMPHIBIANS & REPTILES CHANGE WITH THE ENVIRONMENT.

Vertebrates Adapted to Live on Land Amphibians (frog/toad/salamanders) & Reptiles (turtle/snake/lizards/crocodiles) have adapted to live on land. Some fish can breathe air and walk short distances on land. Some amphibians have adapted to life only in water.

Amphibians: moist skin & eggs without shells Most adult amphibians have: 2 pairs legs (4 limbs), lay eggs in water, get oxygen thru smooth, moist skin, have lungs, sense organs adapted for land. Most live in moist or damp environments Reproduce sexually (female lays eggs in water & male fertilizes them in water with sperm); offspring develop & hatch on own- yolk inside eggs gives nutrients; soft shells so water (with dissolved oxygen) can pass through.

Amphibian Life Cycle Young amphibian hatches as a larva (tadpoles for frogs & toads; look & act like small fish- breathe via gills, swim with tail) After few weeks, tadpole’s body changes (lungs develop, tail shrinks, legs form) Young frog’s body changes: gills stop working so breathes with lungs, uses tongue to capture & eat small animals, uses legs to move around on land. Some amphibians stay near water (sirens, bullfrogs), while some just go to moist areas (wood frogs, toads, salamanders)

Reptiles have dry, scaly skin & lay eggs with shells Most have 2 pairs legs (total 4 limbs); have tough, dry skin covered by scales; get oxygen from air with lungs; sensory organs adapted for land; lay eggs (with shells) on land. Lungs: born with lungs, filled with tiny blood vessels where oxygen is exchanged with carbon dioxide waste. Dry, scaly, skin: covered with scales made of keratin (like fingernails). Thick, waterproof skin protects from environment & predators (but can’t exchange oxygen through skin).

Reptile Eggs with Shells Reptile egg lets vertebrate animals survive in hot, dry environment. Eggs have everything embryo needs (water, nutrients, gas exchange). Reptiles reproduce sexually (sperm fertilizes egg, then shell forms around it-while still within female). Female finds place to lay eggs (usually nest or buries them).

Amphibians & Reptiles are Ectotherms Are Ectotherms: body temperature changes with environmental conditions; can move more quickly when warm. Usually warm themselves in sunlight. Most of food is changed right into energy. Some (alligator & tortoise) may survive long time without eating food. If too hot or too cold, body stops working well. (usually live where temp. doesn’t change too much- or may hibernate & slow down body processes in cold) Many live near water to cool off.