The relative significance of body surface and cloacal respiration in Psolus fabricii (Holothuroidea: Dendrochirotida)
Keyword(s):
Oxygen consumption at 10 °C was measured for Psolus fabricii, in whole animals and in specimens with the cloaca blocked to prevent use of the respiratory trees. In both sets of experiments, oxygen consumption was exponentially related to body size, but larger animals exhibited a significantly greater proportion of oxygen exchange by cloacal respiration. An animal of 80 g wet weight achieves 75% of its respiratory needs by actively pumping water through the cloaca, whereas body surface respiration alone is calculated to be adequate for a 1.9-g animal. It appears that because of their success in shallow areas of dynamic water motion, adult Psolus depend less than other holothurians on body surface respiration.