Intertidal decapods regulate their blood glucose with a significant but transitory (60 min) increase upon exposure to atmospheric air, and this has been considered to be an adaptative response related to the almost complete lack of the Pasteur effect in facultative anaerobes. In these animals we would not observe an increase in substrate availability to cope with the small amount of energy furnished by anaerobic pathways but rather a general metabolic depression. However, this hypothesis has never been tested by conducting similar experiments with infralittoral species. For this reason, groups of five Callinectes sapidus were transferred from sea water to atmospheric air and their blood glucose levels were determined 15, 30, 60, 120 and 240 minutes afterwards. Glucose levels increased gradually from 16.41 +/- 4.45 mg/100 ml to 127.18 +/- 33.40 mg/100ml (mean +/- SEM). The linear relationship between time of exposure and glucose levels suggests that intertidal and infralittoral species present different mechanisms of blood glucose regulation.