New Zealand Journal of Marine and Freshwater Research abstracts

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BURROWING AND BURYING BY THE CRAB MACROPHTHALMUS HIRTIPES

Pauline A. Nye

Department of Psychology, University of Otago, Dunedin, New Zealand

Abstract Macrophthalmus hirtipes (Jacquinot, 1853) excavates burrows under water in soft, muddy sand that remains waterlogged at low tide. The crabs are immersed for at least 4h in every tide. The burrows are usually single, blind-ending, slightly curved passages; their openings do not appear to be deliberately closed by the crabs. Excavation is effected by using one set of walking legs as a scoop while the other set provides sideways traction.

Burrow openings are readily obscured by water movement, so that apparent burrow density does not give a true indication of the number of crabs in an area, but only indicates how many have been active recently; the true density may be found by sieving.

The burrowing activity of M. hirtipes is compared with that of other ocypodid crabs, and the functions of burrows are discussed. A distinction is made between excavating a burrow and rapid burying, because the two behaviours are very different, and must involve different adaptations and selection pressures.

N.Z. Journal of Marine and Freshwater Research 8 (2): 243-54
(Received for publication 22 November 1971; revision received 21 September 1973)

PDF file of entire paper: medium quality (1931K); (scanned from paper original: notes about this process)

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