Salamanders secrete mucus from their skin that in some species is sticky or toxic, protecting them from predation. Bright coloration of some salamanders (aposematic coloration) warns predators that they are not edible. If preyed upon, many salamanders can make new body parts. Salamanders are unique among back-boned animals (vertebrates) in regenerating legs or even eyes with no scarring. If attacked by a predator, some salamanders drop off their tails (autotomy). The salamander might escape while the predator focuses on the detached, wiggling tail. In just a few weeks, a new tail grows. Scientists are studying regeneration in axolotl salamanders. A clump of cells (blastema) forms where a limb has been lost. By reverting to an earlier stage of development (when they were less specialized), the cells can grow into skin, bone, muscle, and other tissues to form a new limb. What scientists find may help make human limb regeneration possible someday.

Amphibians lay eggs that have no shells and must stay moist to survive. Usually, the eggs are laid in water. The larvae that hatch out are aquatic, living in ponds or streams for at least some part of their life cycles. Gills allow them to get oxygen underwater. Their bodies are adapted for swimming, with large tails and small limbs or none at all. Most amphibians undergo a dramatic body transformation (metamorphosis) to become adults. They may absorb their tails and sprout limbs, grow sensory tentacles, and/or get thicker skin. Along with metamorphosis come changes in behavior and diet. For some species, larger mouths with teeth and tongues reflect the switch from algae-eaters to carnivores. For others, sticky toes mean they can climb trees and cling to leaves. While many adult amphibians still live in or near water, they have lungs and other adaptations to life on land.