Arm regeneration in Acrocnida brachiata (Ophiuroidea) at Little Killary, west coast of Ireland

Presence and significance of arm. regeneration were studied in a population of Acrocnida brachiata (Montagu) from Little Wary on the west coast of Ire land. Arm loss appears to be a phenomenon to which A. brachiata is well ada pted, since all individuals examined had recent or older regeneration scars on the arms. While the main cause of arm loss is generally deemed to be su blethal predation, the present study does not clearly support the significa nce of any one species as an important arm predator. However, in the shallo w, high-energy environment of Little Wary, physical stress can also be cons idered as a possible cause of arm loss. Observations made in this study sup port the theory that arm rotation, a procedure where the most damaged arms are withdrawn inside the burrow and are replaced on the sediment surface by less damaged arms, enables the population to withstand high, cumulative le vels of sublethal arm injury.