Intertidal Zone

The intertidal zone, also called the foreshore, is the part of the coastline that lies above the water at low tide and underwater at high tide, the section of the shore that falls within the tidal range. It can be a narrow strip on Pacific islands where the tidal range is small, or a much wider band of shallow beach where the tide rises and falls a long way, and conditions within it swing between fresh, rain diluted water and highly saline, sun dried salt, and between intense sun and near freezing cold, moderated in places by the shade of mangroves and other large plants. Organisms living in the intertidal zone, drawn from groups including sponges, segmented worms, cnidarians, mollusks and arthropods, face strong competition for space along with rapidly changing conditions as the tide moves in and out, but they also benefit from the steady supply of nutrients the tides bring in; the zone is a well known example of an edge habitat where land and sea meet, historically used by people foraging at low tide and still used today by migratory birds feeding on the mollusks and other small animals that live there.