Heart activity and high-pressure circulation in cirripedia

Pulsating hemolymph pressures of remarkable magnitude for invertebrates are prevalent in the Pacific gooseneck barnacle. Mean pressures of 250 centimeters of water are common with pulse pressures up to 70 centimeters of water. The pulsations are distinctly rhythmical and the pulsation rate is highly temperature-dependent. The results strongly suggest that in cirripeds hemolymph is circulated by muscular contractions of a functional heart.