Vertical zonation

The intertidal zone, also known as the foreshore and seashore and sometimes referred to as the littoral zone, is the area that is above water at low tide and under water at high tide (in other words, the area between tide marks). This area can include many different types of habitats, with many types of animals, such as starfish, sea urchins, and numerous species of coral. The well-known area also includes steep rocky cliffs, sandy beaches, or wetlands (e.g., vast mudflats). The area can be a narrow strip, as in Pacific islands that have only a narrow tidal range, or can include many meters of shoreline where shallow beach slopes interact with high tidal excursion. Peritidal zone is similar but a somewhat wider zone, extending from above the highest tide level to below that of the lowest tide level.

Organisms in the intertidal zone are adapted to an environment of harsh extremes. The intertidal zone is also home to many several species from different taxa including Porifera, Annelids, Coelenterates, Mollusks, crustaceans, Arthropods, etc.Water is available regularly with the tides but varies from fresh with rain to highly saline and dry salt with drying between tidal inundations. Wave splash can dislodge residents from the littoral zone. With the intertidal zone's high exposure to the sun, the temperature range can be anything from very hot with full sun to near freezing in colder climates. Some microclimates in the littoral zone are ameliorated by local features and larger plants such as mangroves. Adaptation in the littoral zone allows the use of nutrients supplied in high volume on a regular basis from the sea, which is actively moved to the zone by tides. Edges of habitats, in this case land and sea, are themselves often significant ecologies, and the littoral zone is a prime example.

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