Abstract

Full, R.J., C.F. Herreid II and J.A. Assad. 1985. Energetics of the exercising wharf crab, Sesarma cinereum. Physiol. Zool. 58: 605-615.

Crabs (1.9 g) were exercised for up to 60 min on a miniature treadmill respirometer. O2 consumption, V(O2), at all velocities was 1ow, a maximum of only 1.5 times the resting rate. V(O2) was not related to velocity of running. Five weeks of treadmill training produced a minor rise in V(O2) at the maximum sustainable velocity, but the highest V(O2) was still only two times the resting V(O2). Crabs exercising in 100% O2 significantly increased their endurance capacity, indicating this crab's 02 conductance system is severely limited. Anaerobic metabolism with lactate as an end product supplemented aerobic energy production to a minor extent. Whole-body lactate (WBL) increased at a constant but small rate (0.10 mg/g*min) when the crab ran at the highest velocity (0.14 km/h). Wharf crabs fatigued rapidly when run in a 100% N2 atmosphere, indicating they do not have unusual anaerobic capacities or unusually high levels of O2 stores or phosphagen resources to compensate far the very low V(O2). Hence, all data suggests that Sesarma cinereum has a uniquely reduced metabolic rate during exercise.