AmphibiansClass 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

Adaptationshelp 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 FrogFlectonotus 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 Vertebrates Insects Fish

Worms Frogs

Snails

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.