The investigation of the flsioecological aspects of marine species of commercial interest is of great importance, as some problems related to fisheries could partially or totally be resolved on fisiological basis (Alvarez & Dias, 1971). In this paper, the metabolic demands of Panulirus agus (Latreille) are studied, measured through oxygen consumption in µ1 of O2 /g/h, and compared to the data available for Panulirus laevicauda (Latreille) The study is based in 80 juvenile spiny tobster in several molting stages, hand captured by diving during low tide in coastal waters off the County ofFortaleza. For oxygen consumption determination, the method recommended by Schlieper(1972) was used, the dissolved oxygen measures effected with the aid of an "Oxygen Meter Model 51-A-YSI" The values were refered in µ1 O2 /g/h. The calculation of relationships consumption O2/weight were made using the linear model y = a+ bX, by the method of least squares. The following conclusions were obtained: 1. The O2 consumption, in the different molting stages dim inished as the animal weight increased. 2. No significant difference in O2 consumption was found between males and females. 3. The spiny lobster in study nas in the differents molting stages, low metabolic demands stages D presenting the highest O2 consumption. 4. For each molting stage equation relating weight and O2 consumption were calculated as follows: P. argus P. laevicauda molt A C = 97.55 - 1.36 W r = 0,97 molt A C = 86.17 - 0,99 W molt B C = 87.96 - 1.02 W r = 0.95 molt B C = 87.51 - 1,08 W molt C C = 86.03 - 0.92 W r = 0.98 molt C C = 91.03 - 1,20 W molt D C =107.47 - 1.84 W r = 0.98 molt D C = 87.77 - 0,97 W 5. The calculated values based on the equations are quite similar to those values obtained, thus the utilization of me equations being valid
