A cleaning association between the oceanic crabPlanes minutusand the loggerhead sea turtleCaretta caretta

Columbus crabs,Planes minutus(L.) (Crustacea: Brachyura) are often found on the postero-ventral surfaces of sea turtles, particularly the loggerheadCaretta caretta(L.) (Testudines: Cheloniidae). There has been a general acceptance of a hypothesis that the crabs feed upon turtle faeces. However, evidence is presented here to demonstrate thatPlaneshas a ‘cleaning’ role, feeding on other epibionts (e.g.barnacle cyprids, parasitic amphipods) during daylight hours. At night it is likely that the crabs feed on neustonic animals (e.g.euphausids). The species is also cannibalistic.