This is a study on the sessile species of the intertidal zone which attempts to portray the intricate interplay of structural, physiological and behavioural adaptations that enable one animal to live where its congeners cannot. After outlining the physical and biotic conditions on the shore, each of the successful littoral groups is described in the order in which they appear, starting with those at the highest level and progressing to the sublittoral. Only such structures and physiological modifications are described as are necessary to understand how they are able to live on the shore. Aspects of propagation, dispersal, colonization and interaction between species are discussed in relation to community composition and distribution of animals on the shore.