Thermal Dependence of Locomotor Energetics and Endurance Capacity in the Ghost Crab,Ocypode quadrata

We tested a general model predicting the effect of body temperature $(T_{b})$ on the aerobic capacity, metabolic cost, and endurance of sustained, terrestrial locomotion. In the ghost crab, Ocypode quadrata, $T_{b}$ was a function of ambient temperature $(T_{a})$, relative humidity (RH), and the duration of acute exposure. At 15°C and 24°C, $T_{b}$ was similar to $T_{a}$. At high $T_{a}$ (30°C to 35°C) and low RH (40% to 50%), $T_{b}'s$ were 6°C below $T_{a}$. When the RH was 99%-100% at a $T_{a}$ of 30°C, $T_{b}$ stabilized at 29.7°C. The depression in $T_{b}$ resulted from evaporative water loss. The maximal rate of oxygen consumption $(\dot{V}O_{2max})$, determined during treadmill exercise, decreased by nearly 75% as $T_{b}$ was decreased from 24°C to 15°C. The minimum cost of locomotion ($C_{min}$, the slope of the steady state oxygen consumption vs. speed function) did not change at low $T_{b}$ (15°C). As $T_{b}$ was increased from 24°C to 30°C, $\dot{V}O_{2max}$ decreased to half of its original va...