Symbiotic associations between anthozoans and crustaceans in a temperate coastal area

While symbiotic associations between anemones and crustaceans appear to be common in tropical waters, few such associations are known from temperate waters, except for the symbiosis between hermit crabs and anemones. In this study, observations made with ROVs (remotely operated vehicles) suggested that certain shrimps (Pandalus borealis, P. propinquus, P. montagui and in par- ticular Spirontocaris liljeborgii and Lebbeus polaris) associate with the anemone Bolocera tuediae and the cerianthid Pachycerianthus multiplicatus by aggregating beneath their tentacles. The litho- did crab Lithodes maja was also observed associating with B. tuediae. Laboratory experiments sug- gested that female crabs have a stronger association than males. The associations are presumably facultative commensalistic, as the species of crustaceans live as non-symbionts on the sea floor as well, and the 2 anthozoans do not seem to gain any benefits from the associations. In the field, S. lil- jeborgii had the closest association with both species of anthozoans, while B. tuediae was the pre- ferred host of all associating species. The main benefit for the crustaceans to be associated with the anthozoans is protection against predators. In the case of the shrimps, access to a food source is prob- ably also important.