Variation in the carapace pattern of juvenile Carcinus maenas

摘要: Juvenile shore crabs (Carcinus meanas L.) are highly variable with respect to carapace pattern; young often have conspicuous patches of white or other pigment. Adult crabs, in contrast, drab and usually very similar pattern. It is probable that the patterns serve make cryptic on certain backgrounds. widths lying between 5 15 mm were collected from a range British shores (totalling 48). Pattern incidence was found relate two factors: percentage weed cover (mainly fucoids) shore, amount mud present. Shores high cover, much present, had low frequencies conspicuously patterned crabs. The presence among juvenile population, their absence adults, could result differential visual predation removing progressively so only unpatterned would survive adulthood. Alternatively, individual lose age. Evidence presented support latter hypothesis.