Functional morphology and zonation of three species of sea anemones from rocky shores in southern Chile

Three species of sea anemones, clearly exhibiting zonation on the shore, are grouped into intertidal [Phymactis clematis (Drayton, 1846), Anthothoe chilensis (Lesson, 1830)] and infralittoral [Antholoba achates (Drayton, 1846)] forms. A series of observations revealed that intertidal forms have the ability to retain water in the coelenteron during exposure to air,/while the infralittoral form cannot do so. This different behaviour is attributed to morphological characteristics, such as the specific body shape and the structure of the sphincter and retractor muscles. These features, in combination with specific abiotic factors of the various habitats under consideration, determine the upper limits of distribution of each species, while zonation below these limits seems to be affected in addition by biological interactions.