Habitat choice in the intertidal snail Tegula funebralis

Intraspecific variation in habitat preference was studied in the black turban snail Tegula funebralis (Adams, 1854), at two locations on the northern U.S. Pacific Coast. Studies in 1977 using a mass-marking technique showed that most snails found either above or in permanent tidepools at low tide return to their original habitats within a few days after experimental habitat reversal. This return is not due to homing behavior, but is apparently based on the recognition of ecological characteristics of the two habitats. Experiments in 1978 with individually-marked snails suggest that they prefer specific intertidal levels, and not merely above-pool or in-pool habitats. Theoretical models predict that this behavior could play a major role in the maintenance of genetic polymorphism in a species like T. funebralis, whose intertidal environment is characterized by extreme spatial heterogeneity.