The nature of heat coma in Littorina littorea (Mollusca: Gastropoda)

The nature of heat coma was examined in the edible peri winkle Littorina littorea (L.). Duration of acclimation did not influence heat-coma temperature at 12 degreesC, although other acclimation temperatures were important in influencing thermal tolerance, with positive shifts in coma temperature observed in response to elevated temperatures. Previous thermal history also influenced heat-coma temperatures. Individuals subjected to repeat heat-coma events on a daily basis showed significant declines (P < 0.05) in coma-temperature; in contrast individuals exposed to repeat heat-coma events on a weekly basis showed no decline in thermal tolerance. Size-effects occurred at selected sites, where decreased heat-coma temperatures were recorded in large individuals.