Gill Ventilation in Remora remora

Abstract

the number of external respiratory movements as the water velocity was increased. The rate was noticeably reduced at 20-30 cm/sec and the movements stopped at about 60 cm/sec, at which velocity the fish irrigated the gills in a passive manner. The hydrostatic pressure at this velocity, 1.87 cm H20, corresponded to the maximum differential pressure developed between the buccal and opercular chambers during normal active respiration with no water current. During passive respiration at 60 cm/sec, apparently more water could pass over the gills than was required and the fish continuously adjusted the mouth and opercular openings to regulate the volume flow.