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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.
E.
2.
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
Metamorphosis
1.
Aquatic larvae have gills, tail fin, & a
2-chambered heart
Adults breathe thru
skin, have poorly
developed lungs, &
a 3-chambered heart
F.
3 chambered heart – this heart provides
enough O2 to the body’s cells, since
walking on land requires more energy and
O2 than swimming
1.
1st chamber receives O2-rich
blood from the lungs & skin
 skin must be moist to
exchange O2
2.
2nd chamber receives O2-poor blood
from the body tissues
3.
3rd chamber pumps O2-rich blood
to body tissues & O2-poor blood to
lungs & skin
II.
Diversity of Amphibians
A.
Order ANURA: frogs & toads w/ no tails
Frogs
Toads
Long legs
Short legs
Poorly developed lungs
Well developed lungs
Smooth, moist skin
Bumpy, dry skin
Found in water/moist areas
Found on land/loose soil
No spades on hind legs
Spades for digging in soil
Few are poisonous (dart
frogs)
Many are poisonous
1.
2.
3.
Predators that eat insects & worms
Vocal cords produce sounds to attract
a mate
Low #s of frogs or frogs w/
deformities may signal pollutants
B.
Order CAUDATA: salamanders & newts
1.
long, slender body w/ neck & tail
2.
resemble lizards, but they lack claws
& their skin is smooth & moist
4-toed
Salamander
Red-backed
Salamander
Central Newt – toxic!
Tiger Salamander
C.
Order APODA: caecilians
1.
limbless w/ a short or no tail
2.
found in the tropics & are often blind
3.
internal fertilization