Download Amphibians

Amphibians
SECTION 33.3
Modern Amphibians – Key Characteristics
1.
2.
3.
4.
5.
Legs
Lungs
Double-loop circulation
Partially divided heart
Cutaneous respiration
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
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
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
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