Abstract
The amphipod Gammarus oceanicus was shown to actively avoid a region of anoxia in a preference chamber. Single male animals were found to spend more time and to travel a greater distance in an aerated zone as compared to a corresponding anoxic zone. Also the rate of distance travelled was greater in the anoxic region under test conditions. Observations of these animals at the critical aerated–anoxic water interface zone of the apparatus indicated the functioning of a chemoreceptory mechanism.