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 muchor may hibernate & slow down body processes in cold) • Many live near water to cool off.