“Bandits”

The Trapezia Pocillopora/Acropora Crab, or “Acro Crab”, is a small crustacean which spends its days within the hard, branching Pocillopora and Acropora corals of the South Pacific. Sporting a wide array of colours such as purple, white, or orange, many of them have a brown, black, or blue “mask” across the eyes, thus earning the nickname “bandit crabs.”

But far from being troublemakers, these bandits actually help to prevent their host corals from dying by providing regular caretaking services, routinely sweeping out any sediment that falls onto the coral and thereby preventing tissue necrosis.

In addition, they also protect the corals from some predators by nipping at interlopers and encouraging them to move on. In return the crabs enjoy a secure home and an easy source of food, feeding on the particulates that are trapped by the coral’s polyps, on fallen detritus and on the mucus secreted by the coral itself.Previously considered by reef hobbyists to be a coral "pest," the Acro Crab can actually improve the success of those trying to keep Acropora corals alive in captivity.