Journal of the Royal Society of New Zealand abstracts

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Tidal rhythm and the role of vision in shelter-seeking behaviour of the half-crab Petrolisthes elongatus (Crustacea; Anomura; Porcellanidae)

V. B. Meyer-Rochow*+ and W. P. Meha*

Based on observations and tests in the field, we conclude that during the day Petrolisthes elongatus has a considerably greater tendency to conceal itself at low rather than high tide. We provide evidence that vision is involved in detecting potential rock shelters. To small crabs (carapace lengths no more than 5 mm) a small rock close by, is apparently more attractive than a bigger one at greater distance subtending the same sector of arc. In large crabs (carapace length at least 15 mm) a tendency for the reverse was seen with bigger as well as smaller rocks close by being less attractive than similar shelters 1 m away. We believe that the greater desirability of more distant targets in larger crabs is related to their greater physical stamina and visual sensitivity to extended sources. This allows them to run away from a disturbance further than a small crab.

Keywords: Tidal rhythm, shelter-seeking behaviour, vision, distance perception, intertidal, Crustacea, Petrolisthes elongatus

(c) Journal of The Royal Society of New Zealand,

Volume 24, Number 4, December 1994, pp 423-427

PDF file of entire paper: medium quality (341K); (scanned from paper original: notes about this process)

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