Vernal pools are unique wetland habitats where some of the state’s most recognizable reptiles and amphibians can be found. Vernal pools are small, shallow wetlands that do not have a permanent inlet or outlet of water flow. They fill in the fall or spring when rain or snowmelt drains into shallow depressions, and can retain water due to non-porous soils. Vernal pools only hold water for part of the year and experience a drying phase every year or every few years, usually in late summer.
Because their aquatic habitats are temporary, animals that depend on seasonal pools are adapted for both aquatic and terrestrial habitats at different life stages. These animals also benefit from the dry phase, because it prevents year-round water-dependent animals like fish from living in the pools. Fish prey heavily on eggs and larvae, and without seasonal pools some species would not be able to compete and reproduce. Although there are obvious challenges for an animal using an aquatic environment that disappears for part of the year, the benefit is a habitat free from predation by fish.
