Brachyura and crab-like anomura of New Zealand

Abstract

Crab-1ike marine arthropods are among the most advanced forms of crustaceans. They have a well developed carapace, usually wider than long, short bodies with the abdomen folded underneath as a segmented flap and the first pair of pereiopods chelate. These sometimes fearsome-looking appendages often deter people from handling them but in fact most crabs are easily manipulated once you overcome the initial fear of being bitten. Perhaps this aversion is the reason why there still remains much to be discovered about crabs. Most crabs cannot inflict any sort of damage to a human but those which can are easily handled after a bit of trial and error. The words of Thomson (1932) are probably equally applicable today: ' ... the sea, which teems with animal and vegetable life, and with unrealized sources of national wealth, has hitherto received very little attention. In this general neglect of marine biology the Crustatea have shared. The number of workers who have added to our knowledge of this group is very small ... ' The predatory, commensal and mutualistic relationships of crabs with other marine animals, their reproductive and population dynamics and their importance as members of marine communities are fascinating to the marine ecologist. Various aspects of crab behaviour, burrowing, sound production, masking and foraging are intriguing to the animal behaviourist. Physiological adaptations of their osmotic balance, respiration and ventilation, hormonal control of moulting, autotomy and regeneration of lost limbs, and their highly organised nervous systems are exciting to physiologists. The reasons for the apparently low genetic diversity of crustaceans provides a challenge to geneticists. For the great majority of New Zealand crabs we have barely even begun to scratch the surface of the wide range of studies that are possible.