The function of hemocyanin in respiration of the blue crab Callinectes sapidus

Abstract

Blood PO₂ in the blue crab Callinectes sapidus, a very active species of tropical origin, is lower at 22°C than that of larger crabs in colder waters. These low oxygen levels permit its hemocyanin to be highly oxygenated at the gill, and to deliver almost half of its oxygen to the tissues in resting animals. Sustained muscular activity results in conspicuous decreases in blood PO₂, pH and hemocyanin oxygenation. Although the venous reserve is fully utilized, hemocyanin oxygenation at the gill decreases so much that there is no change in its total quantitative function. The large Bohr shift becomes functional during activity, but its quantitative importance is not clear.