Ontogenetic and interspecific variation in the protection of anemonefishes from sea anemones

Abstract

Anemonefishes are well known for their ability to live unharmed among the stinging tentacles of sea anemones. This study examined whether there is ontogenetic and interspecific variation in the protection of anemonefishes from being stung by symbiotic anemones. Ontogenetic variation in protection was studied by determining if the tentacles of anemones would adhere to the eggs, larvae (0–5 days old), and recently metamorphosed anemonefish juveniles (7–14 days old). Interspecific variation in protection was examined by forcing juveniles of 10 species of anemonefishes to contact the tentacles of up to 9 anemone species. The tentacle adhesive forces of the anemone species were also measured. The eggs of anemonefishes were protected from all species of symbiotic anemones tested. Larval fishes were captured and killed by anemones, but recently metamorphosed juvenile fishes were protected from certain host species. Thus, the anemonefishes developed some form of protection during metamorphosis from a pelagic larva to a benthic juvenile. The juveniles of only one anemonefish species ( Amphiprion percula) were protected from all the symbiotic anemone species tested, while most other anemonefish species were stung by at least one anemone species. The extreme host specialist, Premnas biaculeatus, was only protected from its natural host species ( Entacmaea quadricolor) and was stung by 6 other symbiotic anemone species. The juveniles of all anemonefish species were protected from E. quadricolor, but only a few fish species were able to contact Stichodactyla gigantea without being stung. Fish that were stung by anemone species with strongly adhesive tentacles (e.g., S. gigantea, S. haddoni), were generally captured and killed. However, there was no correlation between the tentacle adhesive force of an anemone species and the number of anemonefish species that it stung.