Energy balance and cold adaptation in the octopus Pareledone charcoti

A complete energy balance equation is calculated for the Antarctic octopus Pareledone charcoti at 0 degrees C. Energy used in respiration, growth, and excretion of nitrogenous and faecal waste, was recorded along with the tot al consumption of energy through food, for three specimens of P. charcoti ( live weights: 73, 51 and 29 g). Growth rates were very slow for cephalopods , with a mean daily increase in body weight of only 0.11%. Assimilation eff iciencies were high, between 95.4 and 97.0%, which is consistent with previ ous work on octopods. The respiration rate in P. charcoti was low, with a m ean of 2.45 mg O-2 h(-1) for a standard animal of 150 g wet mass at 0 degre es C. In the North Sea octopus Eledone cirrhosa, respiration rates of 9.79 mg O-2 h(-1) at 11.5 degrees C and 4.47 mg O-2 h(-1) at 4.5 degrees C for a standard animal of 150 g wet mass were recorded. Respiration rates between P. charcoti and E. cirrhosa were compared using a combined Q(10) value bet ween P. charcoti at 0 degrees C and E. cirrhosa at 4.5 degrees C. This sugg ests that P. charcoti are respiring at a level predicted by E. cirrhosa rat es at 4.5 and 11.5 degrees C extrapolated to 0 degrees C along the curve Q( 10) = 3, with no evidence of metabolic compensation for low temperature. (C ) 2000 Elsevier Science B.V. All rights reserved.