Haemolymph pressure in certain cirripedes

Haemolymph pressure has been measured in the mantle sinus of several balanomorph barnacles and the peduncular sinus of two lepadomorph species. The absolute pressure of balanomorphs was found to be similar to that recorded for other crustaceans. The absolute pressure of lepadomorphs was much higher than that in balanomorphs. Regular puls̀e pressures were synchronized with body movements, cirral extension and valve movement. It is concluded that haemolymph is circulated by general body movements even when the opercular/capitular valves are closed.