Experimental studies on homing in the intertidal patellid limpetCellana tramoserica (Sowerby)

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Abstract
A model of two-dimensional random walk was developed to allow statistical tests for the presence of homing behaviour in intertidal populations of the limpetCellana tramoserica. Not all limpets return to a home-site after feeding excursions. Some move around at random. The latter pattern of movement was tested to justify the assumptions of the model. Limpets can stop homing and begin to move at random; moving limpets can become homers. Thus, random movement and consistent homing behaviour are not discrete patterns of behaviour in a population. Controlled field experiments showed that the proportion of animals which home is not affected by the height on the shore, force of wave action, the cover of macroalga, nor the irregularity of the substratum. Small limpets, however, home more than large ones. Close proximity to other homing limpets causes individuals to stop homing and move away. Alterations of density demonstrated thatCellana shows density-dependent dispersal. More limpets emigrate from areas of increased density and more immigrate into areas of decreased density, when compared with control areas. Less animals immigrate into, and remain in, areas from which microalgal food was experimentally removed. More animals emigrate from these areas. These experiments support the hypothesis that homing behaviour is an adaptation which regulates local density and dispersion to maximize utilization of food resources and, thus, to reduce intraspecific competition for food at high densities of limpets.