Scaling of anaerobic energy metabolism during tail flipping behaviour in the freshwater crayfish, Cherax destructor

Abstract

The allometry of anaerobic metabolism during escape behaviour was examined in the freshwater crayfish, Cherax destructor. Exercise time to exhaustion, and the total number of tail flips, increased with body mass. Concentrations of arginine phosphate and glycogen in the tail musculature of resting-state animals were independent of body mass, as was glycogen concentration following exercise to exhaustion. Lactate produced during exhaustive exercise, and intracellular pH buffering capacity, showed positive allometry. Activities of phosphorylase, phosphofructokinase and lactate dehydrogenase in the tail musculature showed positive allometry, while arginine kinase activity was independent of body mass. The positive allometry of anaerobic scope, reflected in the scaling of glycolytic enzyme activities, scales with the increased power required by larger animals to overcome drag during locomotion through water. The increased capacity for anaerobic muscle work in larger animals scales with anaerobic glycolytic capacity, while the contribution from phosphagen hydrolysis remains constant. Limits to anaerobic capacity are not set by fuel stores, but may involve inhibition of glycolytic enzymes at low pH, and the scaling of intracellular pH buffering. The positive allometry of anaerobic capacity observed for enforced exercise may not be used routinely in nature because of metabolic constraints imposed during recovery.