Ontogenetic shifts in carapace patterning and/or colouration in intertidal and subtidal brachyuran crabs

Abstract

Some juvenile intertidal and subtidal crabs are known to exhibit carapace polymorphism, crypsis, or disruptive colours which are lost as the crabs mature, i.e. they undergo ontogenetic shifts in patterning and/or colouration. These patterns and colours are thought to protect young crabs from visual predators. The transformation is often dramatic and most likely reflects a critical life-stage that is possibly unique to marine arthropods. Two main hypotheses have been proposed to explain changes in colouration as crabs grow: they no longer need such a defense as they become bigger and stronger or, they migrate from nursery habitats to areas where such patterns and colours do not confer protection. To identify the extent of ontogenetic shifts in intertidal and subtidal crab patterning and/or colouration, a database was assembled from the literature (primary and grey); from expert scientific opinions (via personal interviews and email correspondence); and website-derived observations from non-professionals worldwide. © National University of Singapore.