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Summary
The subtidal distribution and abundance of the burrowing lamp urchin, Echinolampas crassa (Bell) 1880, was studied with respect to the topography of a benthic biogenous macro-ripple train by scuba at a depth of 12–23 m. A polar co-ordinate sampling method enabled study of the patch size (9–12 m2) and dispersion pattern, which varied with density; being regular during high density (1,09 m−2) and contagious at low density (0,24 m−2). A significant preference of urchins for ripple slopes and avoidance of troughs as a marginal habitat was found. The annual growth rate, as estimated from size frequency distributions, was 0,5 cm yr−1.
