Oxygen consumption and the respiratory responses to declining oxygen tension in the crab Ebalia tuberosa (Pennant) (Crustacea : Decapoda : Leucosiidae)

Abstract

Oxygen consumption and its relationship to body weight and activity have been examined in Ebalia tuberosa (Pennant). Ebalia showed only very limited ability to regulate their oxygen consumption under conditions of declining PO2. Respiratory independence was markedly affected by the level of activity of the animals. When inactive, respiratory independence was maintained down to a critical PO2 of only about 130 mm Hg while when active, the crabs behaved as perfect conformers. Inactive Ebalia responded to a decrease in PO2 by increasing the pumping activity of the scaphognathites and heart. This increased activity continued even at oxygen tensions lower than the Pc. The rate of reversals of the ventilatory currents did not change with decreasing PO2. In the active crabs, the pumping activity of the scaphognathites and heart, and the rate of current reversals were higher than in the inactive animals, and a decrease in PO2, did not bring about any further change in any of these responses. When exposed to hypoxic conditions for long periods initially inactive crabs survived longer than did active animals.