The littoral zone is the beach area between high and low tides. It also refers to the benthic division – between high tide and a depth of 200 m (656 ft). The larger zone is divided into the eulittoral, from high tide to a 50 m (164 ft) depth, and the sublittoral, from 50–200 m (164–656 ft). The lower edge of the eulittoral is the lowest limit at which abundant attached plants can grow.
Littoral fauna are animals that live on the seashore, in the littoral or intertidal zone. They comprise a special assemblage which are uniquely adapted to being alternately covered and uncovered by the tide. On any one shore the organisms are "zoned," changing from animals adapted to aquatic conditions in the lower regions, to often closely related semiterrestrial species higher up.