Guide Note

All amphibians spend part of their time on land, but rely on water for reproductive purposes and, as such, are the evolutionary link between fish and terrestrial reptiles. Amphibians lack amniotic eggs and are ectothermic (cold-blooded), meaning that they rely on the outside environment to regulate their body temperature. They have the ability, during different phases of their life, to breathe in one of three ways: using lungs, gills, or through their gas-permeable skin. This thin skin allows water, and therefore oxygen, to enter their bodies in moist environments, but also means that water and oxygen will exit their bodies in dry areas, so they are bound to stay close to fresh water at all times. Some may tolerate brackish water, but there are no true saltwater amphibians.

Young amphibians don't resemble their parents; through the process of metamorphosis, they go through three distinct stages—for example: egg, tadpole, and frog—during which they change in body shape, lifestyle, and diet.

1. 32% (1,896) amphibian species are threatened
2. As many as 165 amphibian species may already be extinct
3. At least 34 amphibian species are known to be extinct
4. Another 130 species have not been found in recent years and are possibly extinct

• Wacky Archives: 10 Amphibians You Didn't Know About (January 26, 2008)

• Amazon.com: Amphibian Search Results