Although often small and inconspicuous, vernal pools spring to life as frogs, toads, salamanders and other amphibians converge on them to breed. Vernal pools provide the temporary aquatic environment that supports the eggs and larvae of amphibians. Because they are isolated from other water sources, vernal pools do not support fish species that would prey upon amphibian eggs and larvae. Despite their name, some vernal pools also fill during autumn. Amphibians spend part of their lives living in water and the other part living on land.
Most amphibians lay soft eggs in water.
An egg hatches into an aquatic larval stage which looks and acts quite differently from the more terrestrial adult stage. For instance, toad and frog eggs hatch into tadpoles, which can only survive in water. As the larvae grow, they experience radical physiological changes and are transformed into adults in a process known as metamorphosis. Many salamanders return to their birth pool to breed. Their larvae overwinter in the pool.