29 April 1994
Vol 264, Issue 5159

About The Cover

Four successive molts of an individual predatory crab, Cancer productus. Because crustaceans can only change form when they molt, their shape was thought unlikely to respond to environmental stimuli received during the preceding intermolt. Nonetheless, C. productus grew relatively larger and stronger claws in subsequent molts when their prey had harder shells. Therefore, the rigid exoskeleton does not prevent crustaceans from responding morphologically to environmental change. Longest dimension of largest molt is 60 millimeters. See page 710. [Photo: Richard Kozak]