Comparative analysis of food-finding behavior of an herbivorous and a carnivorous land snail

Although the olfactory capabilities of land snail tentacles have been teste d by lesion studies and unilateral exposure of tentacles to specific odors, studies of a carnivorous species suggest that the anatomical similarities of herbivorous and carnivorous land snails may belie a fundamental differen ce in the way these structures are used to find food. Therefore, we challen ged the herbivore, Anguispira alternata, and the carnivore, Haplotrema conc avum, to find a stationary food source (carrot and caged young prey snail, respectively) under identical still air conditions. The herbivore traveled a significantly shorter distance to the food, even negotiating a barrier pl aced halfway between the snail and its food. The carnivore, on the other ha nd, followed a circuitous, apparently random, path to the food. Subsequent tests revealed that H. concavum readily follows prey slime trails while A. alternata seldom follows conspecific slime trails when a distant food sourc e is available. These results are consistent with what might be expected as adaptations to the usually mobile nature of carnivore prey and the station ary nature of herbivore food plants. The ability of A. alternata to exhibit typical detour behavior is noted.