Transport of oxygen by the blood of the land crab, Gecarcinus lateralis

Abstract

Parameters relating to transport of oxygen were measured in the pericardial blood and venous outflow from the first walking leg of Gecarcinus lateralis. O2-equilibrium curves of the hemocyanin of G. lateralis were found to be sigmoid and, at 27°C and pH 7.45, to have a half-saturation pressure of about 17 mm Hg oxygen. Average partial pressures of oxygen as measured by O2-electrode were 32 mm Hg in pericardial blood and 9 mm Hg in the venous samples. Analysis of the O2-content in corresponding samples by the Van Slyke technique revealed an average of 2.17 volumes % O2-capacity for whole blood, 1.45 volumes % for pericardial blood, and 0.61 volumes % for venous blood. Estimates based on the Van Slyke analyses indicated an average pO2 of 29 and 14 mm Hg in pericardial and venous samples, respectively. These figures agree fairly well with those obtained by means of O2-electrodes. Of the oxygen carried to the tissues, about 94% is carried as oxyhemocyanin and about 6% is carried in physical solution. As the blood passes through the gills, the hemocyanin, on an average, becomes 80-85% saturated with oxygen and returned from the tissues 18-45% saturated with oxygen. These results indicate that the blood of G. lateralis has a higher O2-capacity than the blood of most other decapod crustaceans for which similar information is available. In addition, the blood of G. lateralis transports more oxygen to the tissues per unit volume than do other crustacean bloods. © 1968 American Society of Zoologists.