LONG-LASTING SUBSTRATE MARKING IN THE COLLECTIVE HOMING OF THE GASTROPOD<i>NERITA TEXTILlS</i>

Abstract

Field observations and experiments were conducted on the intertidal gastropod Nerita textilis Gmelin along the Somalian coast to determine if its rhythmical mass-homing includes the detection of durable substrate marking as well as short-term trail-following. The snails' first response to displacement is a zonal orientation compensating for the vertical component of experimental shifting. The homing performance of symmetrically transferred animals supports the hypothesis that a marked area is present in and below the aggregation site, detectable by the homer snails 24 hours after its deposition by spontaneously moving conspecifics. No specific marking of different collective homes resulted from these experiments.