DO ANEMONEFISHES USE MOLECULAR MIMICRY TO AVOID BEING STUNG BY HOST ANEMONES

Anemonefishes are known to have a protective mucous coat that allows t hem to contact the tentacles of their host anemone without being stung . There are two conflicting hypotheses as to the source and biochemica l properties of this mucous coating. One hypothesis proposes that anem onefishes acquire anemone substances from their hosts during the behav ioral process of acclimation, that protect the fish from being stung. Anemonefishes are considered to use anemone mucus as ''chemical camouf lage'' or ''macromolecular mimicry'' to avoid recognition as ''not-sel f'' by the anemone, and possible subsequent stinging. Another hypothes is is that anemonefishes produce their own protective mucus coat, whic h lacks substances that elicit cnida (nematocyst and spirocyst) discha rge by their hosts. The present study used immunological techniques to test whether the anemonefish Amphiprion clarkii (Bennett) (which was innately protected from two of the anemones used in the present study) has a mucous coat that resembles the external mucus of anemones. Poly clonal antibodies were prepared to the mucus of four species of anemon es [Heteractis crispa, (Ehrenberg) Stichodactyla haddoni (Saville-Kent ), Macrodactyla doreenensis (Quoy and Gaimard), and Condylactis gigant ea (Weinland)]. Ouchterlony (double immunodiffusion) tests showed that different antigens were present in the mucus of the four anemone spec ies. Anemone antigens were not detected in the mucous coating of eithe r naive (fish that had never before encountered sea anemones) or assoc iated (those living with sea anemones) anemonefishes in Ouchterlony te sts. However, more sensitive ELISA (enzyme-linked immunosorbent assay) tests showed that anemone mucus antigens were present in the mucous c oating of associated anemonefish, but not naive fish. This showed that an innately protected A. clarkii does not produce a mucus coat that i s biochemically similar to that of anemones, but that the same fish do es acquire anemone substances in its mucus coat when it associates wit h anemones in aquaria. It remains to be shown whether these anemone su bstances actually provide the initial protection for those anemonefish es that must undergo acclimation behavior in order to keep from being stung by their host sea anemones, or additional protection for innatel y protected fishes.