Effects of substratum instability on locomotion and pedal laceration in Metridium senile (Anthozoa: Actiniaria)

Abstract

Field experiments on the west coast of Sweden showed that M. senile produced significantly more lacerates on live mussels Mytilus edulis than on mimic (eviscerated) mussels. In a laboratory flume experiment, the rate of laceration on mimic mussels increased significantly with the frequency of substratum perturbation (overturning) with maximum laceration rates of groups overturned once every 12 and 48 h. Futhermore, the rate of laceration was found to be a function of anemone body size per se. During periods between overturning of the mimics, anemones showed a significant net migration from the protected lower shell to the exposed upper shell in pace with the frequency of overturning. The presence of a vertical flow velocity gradient between and above the mimics supported the hypothesis that migration was due to rheotactic response in M. senile. -from Authors