Variation in foraging activity of Acanthochitona garnoti (Mollusca: Polyplacophora) from different habitats

Abstract

Foraging activity of Acanthochitona garnoti was studied during spring and neap tides in three different habitats: an aeolian sandstone platform, a permanent high-shore rock pool (aeolian shore) and a quartzitic sandstone boulder shore. On exposed rock, A. garnoti was active only during nocturnal low tides, although some individuals were active during early morning low tides when in shade. Chitons from upper-shore pools were active during both day and night low tides. At all sites chitons foraged for longer (x̄ = 5.5 h) and travelled further (x̄ = 313 mm) during a spring tide new moon and least on a spring tide full moon (x̄ = 4.0 h; x̄ = 182 mm). Chitons on the boulder beach travelled greater distances (x̄ = 367 mm) during foraging than those from aeolian shores (x̄ = 105 mm). It is suggested that this is a result of boulder beach chitons having further to travel to find a grazing patch. Finally, A. garnoti was found to have a ranging pattern of activity on boulder shores and a homing pattern on aeolian shores.