Amphibians
Class Amphibia
Amphibians
• Animals that can live on land and in water
Chinese Giant Salamander
Amphibians
• First animals with four limbs
• Tetrapods: vertebrates that have four
limbs.
Acanthostega
• Found in 360 million year-old rocks in
Greenland
• Had lungs and eight-toed legs, but also
had gills and a lateral line system.
Fish to Amphibian Transition
Adaptations
help amphibians live on land
• Large shoulder and
hip bones help
support more weight.
Adaptations
• Interlocking projections on the vertebrae
help keep the backbone from twisting and
sagging.
Adaptations
• Mobile, muscular tongue allows
amphibians to capture and manipulate
food.
Adaptations
• Development of a
middle ear help some
amphibians hear out
of water.
Adaptations
• Breathe through the
skin or with the use of
gills or lungs
Adaptations
• Amphibians have a three-chambered heart
Amphibians return to the water to
reproduce
• Eggs do not have
shells
Strategies to keep eggs wet:
•
•
•
•
Laying eggs directly in water
Laying eggs on moist ground
Wrapping eggs in leaves
Brooding eggs in pockets on the female’s
back
Pygmy Marsupial Frog
Flectonotus pygmaeus
Tadpoles
• Some frogs start as tadpoles
• Have gills and a broad-finned tail
Amphibian Metamorphosis
• Change in form and habits of an animal
• It affects nearly every organ in the
tadpole’s body
Tadpole into Adult Frog
• Gills are reabsorbed and lungs develop
• Circulatory system is reorganized to send
blood to the lungs
• Tail fin is reabsorbed
Tadpole into Adult Frog
• Body grows limbs and completely
reorganizes its skeleton, muscles, and
parts of the nervous system.
• Digestive system is rebuilt to handle a
carnivorous diet.
Three Groups of Modern
Amphibians
• Salamanders
• Frogs
• Caecilians
Salamanders
• More than 300
species
• Long body
• Four walking limbs
• tail
Salamanders
• Walk with a side-to-side movement that
may be similar to ancient tetrapods
• The largest family of salamanders do not
have lungs, so they exchange gases
through the lining of their skin and mouth.
Family Plethodontidae
• Lungless salamanders
• Most common kind
Salamanders
• Larvae and adults are carnivores
Invertebrates
Insects
Worms
Snails
Vertebrates
Fish
Frogs
Frogs
• Over 3000 species
• Largest group of living amphibians
Adult Frogs
• Tailless bodies
• Long, muscular hind
limbs
• Webbed feet
• Exposed eardrums
• Bulging eyes
Adult Frogs
• Bodies adapted for jumping
– Elongated bones in their hips, legs and feet
for increased speed and power
– Hind legs have fused bones that absorb the
shock of landing
Toads
• One family of frogs
• Rougher, bumpier
skin
• Shorter legs- not
good jumpers
• Glands make toxins
that protect them from
predators – also in
tropical frogs
Frogs
• Live in every
environment on Earth
except at the poles
and the driest
deserts.
Caecilians
• Legless, burrowing amphibians
• Live in the tropics, such as South America
Caecilians
• 160 species
• Range from 4 inches
to 5 feet
• Banded bodies that
make them look like
giant earthworms
Caecilians
• Are predators
• Search for earthworms
and grubs
• Have no arms or legs for
burrowing, so have to
move like an earthworm.
• Use hydrostatic skeleton
to stiffen it’s body and
drive its head forward like
a battering ram.