The tentacles of an anemone provide homes to a very select group of animals. The ringed anemone (Bartholomea annulata) and giant Caribbean anemone (Condylactis gigantea), for example, allow cleaning shrimp to live among their tentacles. These tiny transparent boarders remove bits of debris and parasites from anemones. The shrimp may even offer their cleaning services to fish, but if visiting fish show any aggression toward the hosting anemones, the shrimp will defend them fiercely.
The tricolor anemone (Calliactis tricolor), meanwhile, often agrees to a relationship with a hermit crab. The crab approaches the anemone and gently touches it, causing the anemone to retract its tentacles. The crab waits until the anemone relaxes and opens, then picks up the anemone and repositions it closer to its own shell. The anemone slowly climbs onto the dorsal side of the crab shell, where it will remain indefinitely. This arrangement protects the crab that now has a hat of stinging cells. The anemone benefits, also, since it has an
opportunity to travel and find new sources of food.
Several kinds of fish, including species of clown fish such as the one shown in the lower color insert on page C-3, live with anemones in relationships that help both animals. In this partnership, a clown fish hides within the anemone’s tentacles when it feels threatened and dines on bits of food that are left over after the anemone feeds. In return, the clown fish protects the anemone from polyp-eating fish. The wastes produced by the clown fish supply the polyp with life-sustaining nitrogen and phosphorous compounds.
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| clown fish hides within the anemone’s tentacles |