Strategic aspects of time allocation in the ecology of a freshwater pulmonate snail.

The paper describes experiments designed to investigate the influence of starvation on responses to various constant stimuli by Biomphalaria glabrata (Say). The results are discussed in the context of the economic priorities involved in "decisions" to switch from one conflicting behaviour to another. Two pairs of conflicting behaviour patterns are discussed: to aggregate as opposed to feeding in isolation, and to move to the surface for pulmonary gaseous exchange as opposed to remaining submersed involved in feeding behaviour. This evolutionary, strategic perspective is pursued with a consideration of the tactics adopted by starved individuals in relation to obtaining food.