Avoidance of recently eaten foods by land hermit crabs, Coenobita compressus

Land hermit crabs, Coenobita compressus, prefer the odours of foods that they have not recently eaten. I used a laboratory choice assay to quantify observations of these induced food odour preferences and to examine the mechanisms that may underlie the formation of these preferences. A potential benefit of this behaviour to land hermit crabs was examined by measuring the relative growth rates of crabs fed single-item diets and a mixed diet. Sex and age differences among crabs did not affect their formation of odour preferences. Land hermit crabs that were exposed to one food for at least 9 h preferred foods having other odours for the next 6 h. Crabs avoided odours associated with food consumption. In choice assays using artificial diets, crabs consumed more glucose than casein, yet both nutrients generated an equal amount of avoidance. Land hermit crabs that received a multiple-item diet of flowers, snails and seeds had higher relative growth rates than crabs fed single-item diets. Nutritional analyses showed that these foods differed in their nutritional composition, with flowers containing the most carbohydrates, snails containing the most proteins and seeds containing the most lipids. Broader diets resulting from short-term avoidance of food odours may benefit land hermit crabs by increasing relative growth rates, possibly through the consumption of a more nutritionally balanced diet. Copyright 1998 The Association for the Study of Animal Behaviour.