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Chapter 3
Section 3
Amphibians

Amphibian:
– Ectothermic vertebrate that spends its early
life in water

Amphibians spend their adulthood on land

They return to water to reproduce
Amphibians

Reproduction:
– They lay eggs in the water
– Eggs hatch into larvae that swim
 Have gills to obtain oxygen
– Undergo metamorphosis
– As adults they have lungs
 Obtain oxygen and get rid of carbon dioxide through their
thin, moist skin
Amphibians
http://static.ddmcdn.com/gif/frog-life-cycle.gif
Circulation

Tadpole circulatory system
– Single loop while they have gills
– Like fish

Adult circulatory system
– Double loop when they have lungs
– 1st loop: Blood flows from heart to lungs and skin to
pick up oxygen
– 2nd loop: Blood flows to the rest of the body to
deliver oxygen-rich blood
Circulation
http://universe-review.ca/I10-82-circulatory.jpg
Circulation

Chambers of the heart:
– Atria: two upper chambers of the heart that
receive blood
 1 receives oxygen-rich blood from the lungs
 The other receives oxygen-poor blood from the
body
– Ventricle: lower chamber of the heart that
pumps blood out to the lungs and the body
 Oxygen-rich and oxygen-poor blood mix here
Circulation
http://www.coolcompanions.com.au/wp-content/uploads/2010/06/The-threechambered-frog-heart-mixes.jpg
Circulation
http://www.biologycorner.com/resources/frog-heart.gif
Amphibians

Reproduction:
– Male frogs or “peepers” using a call to attract
mates
– Most frogs and toads use external
reproduction
 Female releases eggs that are fertilized by sperm
– Salamanders use internal reproduction
 Eggs are fertilized before they are laid
Amphibians

Reproduction:
– Eggs are coated
with a clear jelly
to remain moist
– Tiny embryo
develops
– Few days later
larvae wriggle
out of the jelly
Amphibians
Amphibians

Care:
– Most young are on their own right away
– Exceptions:
 South American River Toad
– Male presses the eggs into the female’s back
Metamorphosis

Metamorphosis
1. Hind legs appear
2. Changes in the skeleton, circulatory system, and
digestive system
3. Front legs appear
4. Loses its gills and starts to breathe with lungs


Frogs and toad adults look different than
larvae
Salamander larvae resemble the adult
Metamorphosis
http://dj003.k12.sd.us/SCHOOL%20NOTES/029%20Life%2
0cycle%20of%20a%20frog.jpg
Metamorphosis
Moving on Land

Adaptations to life on land:
– Strong skeleton
– Muscular limbs
 1st vertebrates to have legs
– Eyes
 Transparent membrane to keep them from drying
out
– Eyelids
Moving on Land
Moving on Land
Frogs and Toads

Adaptations
– Powerful hind-leg muscles
– Skeleton to absorb shock
– Webbed feet and long toes – Bullfrogs
– Adhesive suckers – Tree frogs
Frogs and Toads

Distinguish a frog from a toad:
– Frog skin is smooth and moist
– Toad skin is dry and bumpy
– Toads have lumps behind their eyes
 Contain a poisonous liquid when attacked
Frog vs. Toad
Frogs and Toads

What do they eat?
– Tadpoles
 Herbivore
– Adult Frogs and Toads
 Predators that eat insects or small animals
 Camouflaged to blend into their environment
– Brownish green to blend into ponds
Salamanders
Keep their tails as adults
 Legs are not adapted for jumping
 Some live in water their whole life while
other live on land

– Some do not have lungs
– They obtain oxygen through their moist skin
– Do not return to water to reproduce
– Lay their eggs on land in moist places
Salamanders
Amphibians in Danger

In danger due to habitat destruction
– Swamps are filled in
– Forest is cut
– Moist area becomes dry

Environmental poisons
– Insecticides and other chemicals pollute water