Vernal pools play an interesting role in the ecosystem as seasonal wetland habitats. They perform valuable economic and ecological functions similar to permanent wetlands. However, it is the dry phase that makes a vernal pool inhospitable to fish. With a top predator missing from the environment, a unique suite of animals adapted to take advantage of this niche. In Pennsylvania, there are eight known animal species that are vernal pool specialists; they use vernal pools almost exclusively to complete a stage of their life cycle. Three species of mole salamanders, wood frogs, spadefoot toads, and two species of fairy shrimp are considered vernal pool obligates.