Responses of the blood cockle Anadara granosa (L.) (Bivalvia: Arcidae) to salinity, hypoxia and aerial exposure

The blood cockle Anadara granosa (L.) is an osmoconformer which responds behaviourally to low salinity by tight and effective shell valve closure, triggered below 19‰. Closure provides protection for relatively short periods, so cockles are vulnerable to low environmental salinities which persist beyond about 3 days. Blood cockles are oxygen regulators which are well adapted to tidal exposure to hypoxia. When emersed they respond by gaping widely and breathing air (aerial VO2 being similar to aquatic VO2). However, survival in humid air is limited; condition is poor after 24 h and cockles start to die after 48 h.