Abstract

Herreid II, C. F., P.J. O'Mahoney and R.J. Full. 1983. Locomotion in land crabs: respiratory and cardiac response of Gecarcinus lateralis. Comp. Biochem. Physiol. 74A: 117-124.

1. Land crabs with a respiratory mask were run on a miniature treadmill at controlled speeds. O2 consumption, V(O2), and CO2 production measurements showed that the aerobic response to exercise was slow 2. Steady-state O2 consumption was not attained during 10 min runs nor when they ran freely for 20 min in a treadmill respirometer. Recovery from exercise was prolonged in both cases. 3. This indicates that this species, like another land crab, Cardisoma guanhumi, relies heavily upon anaerobic fermentation. phosphagen and O2 stores to support its energetic demands during running. 4. Aerobic compensatory devices were evident also. Peak O2 consumption values did tend to rise with increased velocity of running as did the area under the V(O2) curve during running and recovery. 5. Both ventilation volume and O2 extraction also rose during running; the latter seemed to be the most important of the two respiratory compensatory mechanisms. 6. Circulatory adjustments were evident. Heart rate showed a rapid rise with exercise and the O2 pulse (the amount of O2 delivered per heart beat) increased directly with O2 consumption as well. 7. Energetic considerations suggest that running with a mask may be slightly more demanding than free running. 8. Estimation of an energetic cost of transport for this 53g crab suggests it is comparable to that of quadrupedal and bipedal vertebrates of a similar size.