Wetlands are defined by the soils, hydrology, and species that occur within them. Wetland soils, also known as hydric soils, are shaped by water. These soils are saturated or even submerged all or part of the year. Hydric soils vary depending on the composition of the soil and water in the area and therefore, wetlands vary greatly throughout the world.
Wetlands occur in all ecological regions throughout the world except Antarctica. There are wetlands in the Arctic (which include fens, swamps, marshes, and bogs), wetlands along coastlines (such as mangrove forests, coastal swamps, and tidal marshes), and wetlands throughout inland regions (ponds, marshes, swamps, vernal pools, and riparian systems).
Wetlands are highly productive communities and provide habitat and food resources for a wide range of species. Wetlands have a high level of nutrients and coupled with the availability of water they provide ideal habitat for fish, amphibians, shellfish, and insects. Additionally, many birds and mammals rely on wetlands for food, water, breeding grounds, and shelter.