Patterns of nocturnal movement of the long-spined sea urchin Diadema antillarum (Philippi) in Gran Canaria (the Canary Islands, central East Atlantic Ocean).

We tagged individuals of the sea urchin Diadema antillarum (Philippi) around the island of Gran Canaria (The Canary Islands) during winter 2001?2002 using a new technique, consisting of the insertion of a hook fastened to a fishing line into the aboral pole (periproctal membrane). This allowed individual identification of tagged sea urchins. The goals were: (1) to quantify nocturnal movements and the homing behaviour of this echinoid on shallow rocky bottoms, and (2) to assess short term spatial and temporal variability of these movements. Tagged sea urchins displayed clear homing behaviour. The mean distance travelled at night was 3.7±1.2 m (range 1.0?5.1 m). Mean speed of nocturnal movement was 33±26 cm h ^-1 (range 5?110 cm h ^-1). We observed greater movement at midnight than at the beginning and the end of the night. [ABSTRACT FROM AUTHOR]