Respiration in air and water of three mangrove snails

The oxygen consumption of three species of Malaysian mangrove gastropods was measured in air and sea water at the temperatures commonly recorded in the mangrove. The experiments in air were carried out after the animals had regained fluid lost from the mantle due to handling. Fluid loss can have considerable effects on rate of oxygen consumption. Nerita arliculata (Gould) was found throughout the mangrove and experiences from 50 to 92% aerial exposure. It has a gill and a ratio of aerial to aquatic respiration rates of 2.7 at 28°C. 50% of the animals can survive underwater for 72 h at 28°C. The other two species, Cerithidea obtusa (Lamarck) and Cassidula aurisfelis (Brugière) experience over 95% aerial exposure, have their mantle cavities modified as lungs and have air : water respiration rate ratios of 5.5 and 6.0, respectively. 50% can survive from 48 to 36 h underwater at 28°C. Acclimated animals have Q₁₀'s of about 1.6 in air and 1.4 in water. The respiratory physiology of the snails is compared with that of rocky shore species.