Behavioral responses to a change in stimulus: transport vs. attack behavior in a carnivorous land snail, Haplotrema concavum

Haplotremu concavum, a carnivorous land snail, responds differently to the same prey when hunting versus when transporting food. The ability of these animals to distinguish between fresh, unmanipulated or uneaten prey and manipulated or partially eaten prey was tested by switching prey items while the predator was in the process of transporting the prey. Predators responded to a switch from a manipulated egg of Anguispiru ulternata to an unmanipulated egg by suspending transport behavior while the new egg was manipulated. Seven of ten predators responded to a switch from an egg of A. alternata to a conspecific (H. concavum) egg by stopping transport and abandoning the less-preferred food. Predators responded to a switch from partially eaten hatchlings of A. ulternata to fresh but injured hatchlings by stopping transport after the retrieval stage to eat the new hatchling, after which transport was resumed. Predators which were not engaged in transport behavior attacked rather than retrieved fresh, injured hatchling prey. These results suggest that by manipulating its prey, the predator alters the sensory stimulus of the prey by marking the prey with predator mucus which, in turn, elicits the transport behavior by the predatory snail.