ABSTRACT
Commensals were observed on every species with up to twelve individual commensals occurring on a single Nemaster. grandis host. The commensals were dominated by shrimp belonging to the genus Periclimenes and at least two species have been distinguished. Arrow crabs and ophiuroids were also found in close proximity of N. grandis and N. rubiginosa. This is the first reported occurrence of shrimp commensals in association with both N. discoidea and Ctenantedon kinziei. The frequency of crinoid arm regeneration decreased with depth. Predation on commensals and predation of host crinoids may produce damage which results in arm regeneration. N. grandis and N. rubiginosa show the highest numbers of commensals and the highest frequency of arm regeneration. The four crinoid species and the “yellow tip” colour variety of N. rubiginosa can be delineated and separated on the basis of these ecological characteristics alone.
