1. Amphibians
Section 33.3

2. Modern Amphibians – Key Characteristics
Legs
Lungs
Double-loop circulation
Partially divided heart
Cutaneous respiration

3. Respiration Larval amphibians have gills but most adults have lungs
Amphibian lungs do not have very much surface area
Therefore, the lungs are not very efficient
Most amphibians also rely on cutaneous respiration through their thin, moist skin

5. Circulation
Double-loop in amphibians allows more oxygen to travel to tissues: heart  lungs  heart  body This is possible because of the pulmonary veins, which carry oxygen rich blood from the lungs to the heart The amphibian heart is 3-chambered: Right & left atrium – separated by the septum One ventricle – where high O2 blood and low O2 blood will mix

7. Frogs & Toads Go through metamorphosis from tadpole to adult
Not only a change in form, but internal changes as well: tadpoles eat plants, adults are carnivores
Frogs have moist, smooth skin
Toads have drier, bumpy skin

9. Salamanders, Newts, & Caecilians
Long and skinny with legs (except caecilians)
Most live on land – many lay their eggs in moist areas
Caecilians have no legs – burrow underground; mostly tropical