Oxygen consumption of the purple sea urchin with special reference to the reproductive cycle.

1. The rate of respiration (Qo2) of the sea urchin Strongylocentrotus purpuratus measured with an oxygen electrode parallels but is somewhat lower than that determined manometrically on the same individuals under the same conditions. The higher values of the Qo2 obtained manometrically are attributable to the higher partial pressure of oxygen (ppO2) in the fluid of the manometric vessels continuously equilibrated with air as compared to the closed chamber used with the oxygen electrode, in which the ppO2 is continuously falling.2. The effects of a number of factors on Qo2 were determined: ppO2 (including oxygen enrichment), relation between ambient oxygen partial pressure (AO2), perivisceral oxygen partial pressure (PvfO2) and effect of body size on Qo2, oxygen consumption of isolated and intact body wall; and the main thrust of this investigation—the change in oxygen consumption during the reproductive cycle.3. The sea urchin is an oxygen conformer, its oxygen consumption being dependent upon the oxygen ...