A Review and a Model of Decorating Behavior in Spider Crabs (Decapoda, Brachyura, Majidae)

Spider crabs (family Majidae) often decorate themselves: that is, they put pieces of marine organisms among the hooked setae of the exoskeleton. This behavior can be absent in large crabs or those that live at great depths, on sand or in narrow crevices. Although some species put edible materials on their bodies and later remove and eat them, the majority of the spider crabs decorate themselves to camouflage themselves against predators. A model of the level of decoration is presented, from none at all to complete coverage of the dorsal surface. Important factors that affect the level are the evolutionary state, habitat, size, feeding and particularly the predators of the species of spider crab.