Following our review of crustacean relationships with corals that we accoutered during the Fluval Sea Flores expedition, we are left wondering why we never see these associations in aquarium. One other crustacean that we often come to meet even together with our last candidate Vir philippinensis is the Orangutan crab that is currently described as Achaeus japonicus but should classified in another species of the genus Oncinopus sp soon.
Unlike its fellow, very-threatened Indonesian terrestrial namesake, this furry-looking species is widely encountered around Asian reefs. Again like Vir philippinensis its best symbiont habitat is the corals of the Euphyllidae family, the Euphyllia, Plerogyra and Physogyra genera. Apparently it collects plankton and suspended particles that it collects with the hair on its first pair of walking legs but it probably feeds also on food collected by the coral.
It’s probably better to avoid stuffing any bubble coral less than 5 inches with one of these crabs otherwise it might be too stressful for the coral to cope with. And only reserve it for the coral that is well acclimated, growing and healthy. These crabs are pretty common in many part of the Asian region where fishes and corals are collected.
They probably fall off the corals during collection and transportation, or may be the collector remove them thinking they’re a parasite and could damage the coral. Which they’re probably right, as the coral already have to go through a lot, so stressing factors must be reduced to the minimum.
But if demand for orangutan crab grows, and collector could manage to earn and easy extra income, they could easily collect and ship them separately from the corals. The orangutan crab is certainly a very interesting addition of symbiotic life to add and observe in a reef tank.