Foraging activity of the sand beach isopod scyphax ornatus dana

Abstract

The terrestrial isopod Scyphax ornatus lives on exposed sand beaches. Adult isopods spent the daytime in burrows near the high water mark and made nightly foraging excursions over the uncovered middle beach. Hourly records of their night time distribution showed that Scyphax congregated near the water’s edge during the last 4 h of flood tide, where they fed on carrion. Insects (mostly drowned honey bees) were the main food item, but coelenterates, amphipods, crabs, and goose barnacles were also eaten. During ebb and early flood tides Scyphax occurred at low densities over the uncovered middle beach. Analysis of the distribution of large and small food items on the beach showed that by feeding during the flood tide, Scyphax exploited a rich concentration of carrion that accumulated in the swash zone and that was moved slowly up the beach by the incoming tide. © 1987 Taylor & Francis Group, LLC.