Growth and metabolism in a marine nematode,Enoplus communis Bastian

Summary The life history and metabolism of a marine nematode, Enoplus communisBastian, was studied. The species has an annual life cycle, spawning taking place in early spring. Maturity is reached in fall and early winter, and both sexes overwinter with their gonads fully developed.The metabolism is not temperature-compensated and there is no difference in respiration between the two sexes.The respiration rate is fairly low in the fertilized, uncleaved eggs (about 600 mm³ O₂/g/hr). Right after hatching, the oxygen consumption increases sharply to a value about three times that of the eggs. Then it drops quickly, but in animals weighing between 6 and 10 g, another sudden rise occurs, followed by a second drop and subsequent leveling of the curve. The first increase in metabolic rate from egg to first juvenile stage might be due to the activation of metabolically important substances. The following changes, however, are most likely correlated with the process of molting and are probably due to changes in the percentage of dry tissue matter in animals prior to and after ecdysis.The large fluctuations in respiration rate occuring in animals of different size, despite a constant surface/volume ratio, suggest that body surface proper does not control oxygen consumption in this species.Contribution no. 1059 from the Woods Hole Oceanographic Institution, Woods Hole, Mass.Supported by NSF grant G-4813.