An interdisciplinary approach to the study of foraging behaviour in the predatory gastropod, nucella lapillus (l.)

Nucella lapillus is an ideal subject for investigating general aspects of foraging behaviour under field conditions. When foraging, it moves short distances and feeds principally on barnacles and mussels, taking from several hours to days to handle each prey item. Consequently, marked snails can be followed daily and accurate diet histories compiled. Such studies reveal great variation in foraging behaviour, both within individuals at different times and among individuals during any one period of time. This variation can only be explained by a comprehensive account of endogenous and exogenous factors, requiring combined physiological, behavioural, ecological and genetical approaches. Dynamic programming is a modelling technique that readily accommodates such an interdisciplinary approach and we have used it to examine the effects of endogenous (gut fullness, level of energy reserves) and exogenous factors (perceived risk of mortality) on the foraging behaviour of N. lapillus. While these factors account for a significant proportion of variation in the foraging behaviour of N. lapillus, there remains much that is not explained. We suggest that the cycle of resource allocation to reproduction and its interaction with risk of mortality when foraging will prove to have an important influence on the foraging behaviour of this intertidal gastropod.