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Nature. 2006 Apr 20;440(7087):1005.

Biomechanics: a pneumo-hydrostatic skeleton in land crabs.

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Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599, USA.


Like their aquatic counterparts, terrestrial crabs repeatedly shed their rigid exoskeleton during moulting. But in the case of land crabs, little water is available to provide a temporary hydrostatic skeleton before the new skeleton hardens, and air does not provide the buoyancy necessary to support the animal. Here we show that whenever its exoskeleton is shed, the blackback land crab Gecarcinus lateralis relies on an unconventional type of hydrostatic skeleton that uses both gas and liquid (a 'pneumo-hydrostat'). To our knowledge, this is the first experimental evidence for a locomotor skeleton that depends on a gas. It establishes a new category of hydrostatic skeletal support and possibly a critical adaptation to life on land for the Crustacea.

[Indexed for MEDLINE]

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