Pedal disk detachment of the sea anemone Anemonia viridis: a newly recognized response to tentacular contact between colour varieties
R.B. Williams

Experiments have been carried out on behavioural interactions between two colour varieties of the nominal sea anemone species Anemonia viridis from Tenerife, Las Islas Canarias. Two separate forms of behaviour were observed in response to mutual tentacular contact between individuals: acrorhagial aggression, a well known phenomenon, and pedal disk detachment, a newly recognized response of anemones to this particular stimulus. In five experiments involving 70 anemones, the two kinds of behaviour appeared to be mutually exclusive, the overall frequency of aggression being 13 % and of detachment, 36 %. Aggression was apparently modifiable by habituation but pedal disk detachment was not. Detachment seemed to involve a somewhat less precise allogeneic recognition than that involved in aggression. Both kinds of behaviour appear to be potentially effective in keeping anemones spaced apart but pedal disk detachment might achieve this object with the expenditure of less energy. Current knowledge of the different underlying physiological mechanisms of acrorhagial aggression and pedal disk detachment of sea anemones in response to various other stimuli is discussed. The newly recognized response ("peeling") is distinct from the pedal detachment behaviour exhibited as part of the escape/swimming responses of some actinostolid anemones and the shell-climbing activities of symbiotic hormathiid anemones.

Keywords: Acrorhagi, aggression, detachment, pedal disk, peeling, sea anemones, Tenerife.
Contents of this volume Sci. Mar. 56(4) : 337-346 Back PDF
Please, send comments to
ICM (CSIC) - Passeig Marítim de la Barceloneta, 37-49. E-08003 Barcelona (Spain)