Eco-ethological aspects of homing behaviour in molluscs

Abstract

Both intertidal chitons and gastropods, and land pulmonates adopt movement patterns centred around a refuge where physical and biotic stress can be avoided. In rocky shore chitons and gastropods the homing behaviour is the basis of a complex isozonal pattern different from the isophasic model shown by mobile arthropods and vertebrates. Homing to a scar or to a permanent and personal home reduces dehydration during exposure to air and protects from predation. The occurrence of natural homing in land pulmonates is less investigated, but some species show a distinct homing performance when displaced several tens of metres from their shelters. Both intertidal and land molluscs may also perform collective homing based on interindividual communication. Chemoreception is deeply involved in the homing of both groups. The homing of intertidal chitons and gastropods relies mostly on trail following based on chemical detection. The trail associated information may be personal in solitary homers, while it is species-specific in the collective homers. The trail may be intrinsically polarized, which allows correct homeward re-trailing. Land pulmonates also show a definite trail following capacity, but here homing relies more on the distant chemoreception of home odours.