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You are here:   OldClasses > 2012 > Trapezia cymodoce | Jonathon Schwartz




Trapezia cymodoce                                Blue Coral Crab

Jonathon Schwartz (2012)




Fact Sheet



Physical Description


Life History & Behaviour

Anatomy & Physiology

Evolution & Systematics

Biogeographic Distribution

Conservation & Threats

References & Links


Trapezia cymodoce is a small crab that is an obligate symbiont of Pocillopora corals. They live within the branches on these coral, where they receive protection from predation as well as their food source; coral mucous. In return the coral gets a cleaner of excess sediment and a guard to fend away coral predators such as the Crown-of-Thorns starfish.  T. cymodoce can be found living within Pocillopora corals throughout the Heron Island reef and they have wide tropical distribution from the Red sea, thru the Indo-West pacific and out into the Central South Pacific. These crabs typically occur in heterosexual pairs, with only a single pair typically found inhabiting and guarding a single Pocillopora coral head. Males are thought to undergo nocturnal migrations in order to find a better coral head. We tested this in a laboratory setting by placing males in tanks with a number of Pocilloporid coral heads of differing characteristics (large vs small, good vs bad quality) in order to determine factors controlling these migrations. We found size of coral heads played a large role in migration and that migrations were also undertaken by female crabs of the species.