Anemones are solitary polyps with mesenteries in multiples of six and without skeletons. Considerably larger than hydrozoan polyps they have adopted three different life styles:
Sea Anemones are mostly sessile solitary animals living in coastal and deep waters. A prominent feature of the intertidal zone around Britain, they withstand exposure by growing in damp crevices and withdrawing their tentacles into their bodies.
Tube-dwelling anemones live within tubes of mucus embedded in sand. Only their tentacles protrude to catch their prey.
Parasitic anemones live symbiotically with hermit crabs. Initially free-living Calliactis spp. are placed on the shells in which the crabs live by the crabs themselves. Adamsia spp. grow permanently around the abdomen of their crab hosts. The crabs are protected by the anemones; the anemones gain food plus the benefits of being mobile.