Animals That Borrow Other Species as Defenses, Disguises, and Shelters

Anemonefish have turned one of the reef’s dangerous neighborhoods into a remarkably effective home. Sea anemones possess tentacles packed with nematocysts capable of stinging and immobilizing many small animals that make contact with them. Yet anemonefish can swim directly among those tentacles and retreat deep into them when predators approach. Their protection involves a specialized mucus coating and a complex relationship with the host anemone that prevents the fish from triggering the same stinging response suffered by many other creatures. The arrangement is not one-sided. Anemonefish can defend their hosts from certain predators, provide nutrients through waste, improve water circulation around the tentacles, and attract potential food toward the anemone. Different anemonefish species associate with particular host species rather than treating every sea anemone as interchangeable housing. Young fish must locate appropriate hosts, and chemical and sensory cues appear to play important roles in that process. Once established, the tentacles create a refuge that many larger predators cannot safely enter.