Abstract
The branchial ventilatory behaviour of the Red Sea semi-terrestrial crab Ocypode saratan is described. Examination of scaphognathite beat patterns indicated a number of distinct ventilation strategies, depending on whether crabs were emersed or were immersed in sea water. In the former case, the pattern employed depended on the crab's activity state and on its need to replenish branchial water. The volume of air ventilated by rested crabs was determined.