Homing pattern, activity area and trail following of the high shore Mediterranean limpet Patella rustica L. (Mollusca Gastropoda)

摘要

Motographic recordings using time-lapse photography have been carried out on the intertidal limpetPatella rusticaon the boulders of a breakwater in central Italy. The reconstruction and analysis of the individual paths allowed a detailed description of the geometry of foraging excursions of this algal grazer.P. rusticaat Cala Calera showed a consistent homing pattern and reuse of the same home scar over long periods. Foraging excursions were scattered around the scar, but longest excursions were upwardly polarized, minimizing the overlap of grazing area with respect to other species (P. caeruleaandP. aspera) coexisting on the same shore. The segmentai analysis of the foraging routes pointed out a typical tri-phasic pattern of activity: relatively fast outward trip, slow and randomly oriented grazing in the central part of the path, and fast locomotor activity during the homeward lag. Limpets showed an extensive use of intra-individual trail following during the return phase of each excursion, while very low overlap appeared between successive excursions of the same individual. On the other hand, the long term monitoring of spatial activity showed a persistent fidelity to the home scar and relative constancy of the individual feeding area.