Comparative study on the behavioral, ventilatory, and respiratory responses of hypogean and epigean crustaceans to long-term starvation and subsequent feeding

Survival, oxygen consumption, locomotory activity and ventilatory activity were recorded during a 180-day starvation period and a subsequent 15-day feeding phase in 3 hypogean crustaceans, Niphargus rhenorhodanensis, Niphargus virei, and Stenasellus virei. For comparison, these parameters were also recorded during a 28-day starvation period and a subsequent 7-day feeding phase in two morphologically close epigean crustaceans, Gammarus fossarum and Asellus aquaticus. Hypogean crustaceans were better adapted to lack of food than epigean ones and all crustaceans previously studied, with survival times largely longer than 200 days. During long term starvation, the locomotory, ventilatory, and respiratory rates were drastically lowered in subterranean species, whereas surface species showed lower decreases in these rates and responded by a marked and transitory hyperactivity. The higher reduction in metabolic rate by hypogean species would ensure their survival during prolonged periods of food deprivation. We propose an energy strategy for food-limited hypogean crustaceans involving the ability 1) to withstand long-term starvation, and 2) to use the consumed food very efficiently. Resistance to starvation would probably involve a state of temporary torpor during which the subterranean crustaceans subsist on a high energy reserve, such as lipid stores.