Respiration of opistophthalmus pugnax (thorell) (scorpionidae) after treadmill exercise and book lung occlusion

Abstract

After the four spiracle pairs of Opistophthalmus pugnax were stepwise occluded, the oxygen consumption rate (MO2) and the accumulation of d-lactate in the haemolymph were measured. D-lactate and MO2 was also measured during a 15-minute treadmill exercise at a run speed of 0.025 m/sec. The highest d-lactate concentration of 15 mmol/l was obtained after a 15-minute exercise followed by 11 mmol/l d-lactate when all eight spiracles were closed off for one hour. The MO2 value of 1.93 mmol/l obtained from four closed spiracles does not differ significantly (P<0.05, t-test) compared with the MO2 value of eight open spiracles. Possible mechanisms of metabolic rate depression and metabolic down-regulation are discussed. Low haemolymphpH (7.38±0.08) in O. latimanus and other scorpions compared with other terrestrial arthropods are a hallmark inherent to scorpions living in dry xeric conditions