What makes an amphibian an amphibian?
Amphibians have an endoskeleton (meaning an internal skeletal system).
Amphibian skin does not have scales and allows fluids to pass through (permeable). Typically, amphibians have moist, slippery skin. Some amphibians, like toads, have drier, bumpy skin.
Amphibians typically have webbed toes and skin covered feet. (Amphibians do not have claws.)
Most adult amphibians breathe through lungs and/or through their skin. Breathing through the skin is called cutaneous respiration. To breathe through their skin, the skin must stay moist/wet.
Early in life, amphibians have gills for breathing. Most will lose their gills as they become adults, however some will keep their gills throughout their life spans.
Amphibians are ectotherms. This means that their body temperature varies with the temperature of their surroundings.
Eggs and Young:
Amphibians lay eggs. Amphibian eggs must be laid in or near water to stay moist.