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the biological zone located just above the high-tide level, at the boundary between the sea and the land. Occasionally covered by water when wind surges occur, the supralittoral zone is sometimes regarded as the upper level of the littoral.
In the supralittoral zone, both marine and land flora and fauna are found. There are few animal species, but the sizes of the populations may be very large. Certain flowering plants, lichens, and algae are characteristic of the zone. Insects inhabit material washed up by the sea, and marine worms, mollusks, and crustaceans live in the wet ground. Sand hoppers and crabs, including hermit crabs, are capable of leaving the supralittoral zone for long times and traveling considerable distances inland. Also associated with the zone are sea turtles, such fish as climbing perch and mudskippers, and such pinnipeds as walrus and seals, including elephant seals. Terrestrial vertebrates and birds find food in the supralittoral zone.
The supralittoral zone is most extensively developed in the temperate latitudes. In the polar regions and the tropics, the animal world of the supralittoral zone is limited by ice cover or insolation.