Oxygen consumption and the use of metabolic reserves during starvation and aestivation in Bulinus (Physopsis) africanus (Pulmonata: Planorbidae).

Aestivating Bulinus (Physopsis) africanus (Krauss) snails are shown to have a lower oxygen consumption rate than those starving in water. This lowered oxygen uptake may possibly be brought about by change to a different metabolic pathway, since the slope of the log rate/temperature regression for oxygen consumption by aestivating snails is significantly different from those for fed and starving individuals. Starving snails use metabolic reserves in the form of protein, carbohydrate and lipid more rapidly than do aestivating snails, and this economy is commensurate, at least over a period of 21 days, with the reduction in oxygen consumption which characterises aestivation. The ability to effect this change upon being removed from water, although linked to the ability to survive exposure, high temperatures and starvation, is not shared by all individuals in the population studied. This can account for reported variations, both within and between populations of planorbid species, in their ability to survive out of water.