Aerobic response to exercise of the fastest land crab

Abstract

To view the aerobic response to exercise, the ghost crab Ocypode guadichaudii was run in a treadmill respirometer at three velocities (0.13, 0.19, and 0.28 km/h) while oxygen consumption (VO2) was monitored. A steady-state VO2 that increased linearly with velocity was attained. VO2 transient periods at the beginning and end of exercise were extremely rapid with half times from 50 to 150 s. The magnitude of oxygen deficit and debt were small and both showed increases with an increase in velocity. Oxygen debt was measured at each velocity after 4-, 10-, and 20-min exercise bouts. No change in the magnitude of oxygen debt was observed with respect to exercise duration. Maximal VO2 was 11.9 times the average resting VO2. Oxygen uptake kinetics have shown only very sluggish and reduced rates in five other more sedentary crab species previously tested. The aerobic response pattern observed in the present study is more comparable to that of exercising mammals and highly aerobic ectothermic vertebrates. This suggests that the ghost crab meets the energy demand of sustained exercise by aerobic ATP production in contrast to many other crab species.

Skeletal muscle fiber types in the ghost crab,Ocypode quadrata:implications for running performance

“…This type of muscle organization is similar to the twogeared system in fish, where the slower fiber types drive slow sustained swimming and the more powerful fast muscles power escape responses (Rome et al, 1988). Physiological measurements support this idea, as slow locomotion can be sustained by the crabs for over an hour but endurance capacity is greatly reduced at speeds greater than 30 cm s -1 and sprints can be sustained for only seconds (Full, 1987;Full and Herreid, 1983;Full and Weinstein, 1992). Exercise leads to rapid accumulation of lactate in ghost crabs but intermittent exercise allows for prolonged activity and greater distance capacity than prolonged slow locomotion (Full, 1987;Full and Weinstein, 1992;Weinstein and Full, 1992).…”

“…Ghost crabs exhibit remarkable athletic capabilities that rival those of comparably sized mammals, with maximum running speeds approaching 4 m s -1 and an aerobic scope of nearly 12 (Full and Herreid, 1983;Full and Weinstein, 1992;Hafemann and Hubbard, 1969). In the current study, running speed in O. quadrata increased as a function of mass 0.31 , meaning that running speed increases as crabs get larger but then levels off at a maximum of just over 1 m s -1 for crabs of ~30 g and larger (Fig.…”

“…Sustained slow locomotion relies on aerobic metabolism whereas short sprints depend on glycolytic muscle activity and result in lactic acid build-up (Full, 1987). The factorial scope of exercising ghost crabs (approximately 8-12 times the resting metabolic rate) is more typical to that of active ectothermic vertebrates and mammals than to an invertebrate (Full, 1987;Full and Herreid, 1983). Biomechanical studies reveal that in spite of some obvious differences between crabs and terrestrial vertebrates, ghost crabs exhibit many of the same features of locomotion as other running animals.…”

Energy metabolism and metabolic depression during exercise inCallinectes sapidus, the Atlantic blue crab: effects of the bacterial pathogenVibrio campbellii

“…The factorial metabolic scope of activity, defined as the ratio of active to resting oxygen uptake (Full and Herreid, 1983) is rather small, ranging from two to seven in most decapod crustaceans -1 and during a 3h recovery from activity. Values are means ± s.e.m.…”

“…Highly aerobic crustaceans, such as the blue crab, typically have a small oxygen deficit recovery (e.g. Booth et al, 1982) and oxygen uptake often returns to preactivity levels within 20-45min (Herreid et al, 1979;Booth et al, 1982;Full and Herreid, 1983;Houlihan and Innes, 1984;Hamilton and Houlihan, 1992). However, in organisms more reliant on anaerobic pathways to fuel energy demands during activity, this recovery may take as long as 5-24h McMahon et al, 1979;Wood and Randall, 1981).…”