FORAGING AND HOMING BEHAVIOR IN THE HIGH-SHORE, CREVICE-DWELLING LIMPET HELCION PECTUNCULUS (PROSOBRANCHIA, PATELLIDAE)

The foraging activity of the high-shore, crevice-dwelling limpet Helci on pectunculus (Gmelin, 1791) (Prosobranchia: Patellidae) from an expo sed shore on the eastern Cape coast of South Africa was monitored. Act ivity was compared during spring and neap tides and between spring, su mmer, autumn and winter. Rhythms of activity in this limpet varied dep ending upon microhabitat; individuals inhabiting both east- and west-f acing rock surfaces were active during nocturnal low tides, but limpet s on west-facing rock surfaces were also active during daytime low tid es, whilst in the shade. Individuals travelled further during foraging excursions in winter ((x) over bar = 85.53 cm) than in either spring ((x) over bar = 55.7 cm) or summer ((x) over bar = 48.8 cm) and also d uring spring low tides ((x) over bar = 89.8 cm) compared with neaps (( x) over bar = 40.9 cm). H. pectunculus exhibited rigid homing to a fix ed scar within a crevice, and feeding excursions were found to consist of three distinct phases: a relatively rapid outward phase. a much sl ower foraging phase and a rapid homeward phase. Whether or not these l impets graze throughout an excursion is not known. Foraging was always highly directional, with a mean vector which took limpets onto an are a of the rock face with the highest microalgal biomass. The fact that H. pectunculus took advantage of optimal feeding areas and memorized t heir location to enable return visits suggests a learning component in herbivorous gastropod foraging behaviour.