Chapter 28.3 – Class: AMPHIBIA I.Characteristics A.Thin, moist skin for breathing thru it: cutaneous respiration B.Most have 4 legs C.Most live on land – but water is required due to external fertilization: 1.water is needed as a medium to transport sperm 2.eggs lack protective membranes & a shell – they would dry out on land

D.Ectotherm – an animal that has a variable temperature; heat is from its environment 1.Body reactions require specific temperatures, so amphibians are dormant in very hot & cold seasons E.Metamorphosis 1.Aquatic larvae have gills, tail fin, &a 2-chambered heart 2.Adults breathe thru skin, have poorly developed lungs, & a 3-chambered heart

F.3 chambered heart – this heart provides enough O 2 to the body’s cells, since walking on land requires more energy and O 2 than swimming 1.1 st chamber receives O 2 -rich blood from the lungs & skin  skin must be moist to exchange O nd chamber receives O 2 -poor blood from the body tissues 3.3rd chamber pumps O 2 -rich blood to body tissues & O 2 -poor blood to lungs & skin

II.Diversity of Amphibians A.Order ANURA: frogs & toads w/ no tails 1.Predators that eat insects & worms 2.Vocal cords produce sounds to attract a mate 3.Low #s of frogs or frogs w/ deformities may signal pollutants FrogsToads Long legsShort legs Poorly developed lungsWell developed lungs Smooth, moist skinBumpy, dry skin Found in water/moist areasFound on land/loose soil No spades on hind legsSpades for digging in soil Few are poisonous (dart frogs) Many are poisonous

B.Order CAUDATA: salamanders & newts 1.long, slender body w/ neck & tail 2.resemble lizards, but they lack claws & their skin is smooth & moist Central Newt – toxic! Red-backed Salamander Tiger Salamander 4-toed Salamander

C.Order APODA: caecilians 1.limbless w/ a short or no tail 2.found in the tropics & are often blind 3.internal fertilization