Fig. 2. Preventing aerial respiration for 3 days does not alter subsequent aerial respiratory behaviour in the hypoxic training/testing apparatus. 12 snails were tested (Before) in the hypoxic testing apparatus as described in Materials and methods. 1 day following training they were placed for 3 days in a eumoxic aquarium with a barrier that prevented them from reaching the surface of the water, so that they could not perform aerial respiration. After 3 days the snails were tested (After) in the hypoxic training/testing apparatus and responded no differently (paired t-test; NS, P>0.05) than they did before being placed in a situation where they were not able to perform aerial respiration.