Respiratory mechanisms and metabolic adaptations of an intertidal crab, Chasmagnathus granulata (Dana, 1851)

1.1. The ventilatory mechanism, gill area, sites of oxygen uptake, oxygen consumption and activity of a crab from south Brazil, Chasmagnathus granulata, were investigated.2.2. The oxygen uptake seems to be restricted to the gill lamellae.3.3. The gill area varies with the wet body weight, being relatively higher in smaller animals. There is not a significative reduction of the gill area in relation to species of the infralittoral zone.4.4. C. granulata presents a mechanism for recirculating the water of its branchial chamber when exposed to atmospheric air.5.5. The oxygen consumption and activity are reduced when the animals are exposed to atmospheric air. The reduction in the oxygen consumption may be related to the poorly adapted respiratory system, while the decrease in activity may be a mechanism for saving energy during this hypoxic period.