AVOIDANCE OF RECENTLY EATEN FOODS BY LAND HERMIT-CRABS, COENOBITA-COMPRESSUS

Land hermit crabs, Coenobita compressus, prefer the odours of foods th at they have not recently eaten. I used a laboratory choice assay to q uantify observations of these induced food odour preferences and to ex amine the mechanisms that may underlie the formation of these preferen ces. A potential benefit of this behaviour to land hermit crabs was ex amined by measuring the relative growth rates of crabs fed single-item diets and a mixed diet. Sex and age differences among crabs did not a ffect their formation of odour preferences. Land hermit crabs that wer e exposed to one food for at least 9 h preferred foods having other od ours for the next 6 h. Crabs avoided odours associated with food consu mption. In choice assays using artificial diets, crabs consumed more g lucose than casein, yet both nutrients generated an equal amount of av oidance. Land hermit crabs that received a multiple-item diet of flowe rs, snails and seeds had higher relative growth rates than crabs fed s ingle-item diets. Nutritional analyses showed that these foods differe d in their nutritional composition, with flowers containing the most c arbohydrates, 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 grow th rates, possibly through the consumption of a more nutritionally bal anced diet. (C) 1998 The Association for the Study of Animal Behaviour .