Insights into prey handling and feeding strategies by ghost crabs on sea turtle eggs and hatchlings

Abstract

The feeding behaviour on sea turtle eggs and hatchlings by the golden ghost crab Ocypode convexa, a species endemic to the west coast of Australia, was observed in field and laboratory settings using infrared videography. On beaches where ghost crab densities are high, multiple crabs can feed on nests over several nights, often resulting in destruction of clutches. Crabs appear to anticipate the emergence of hatchlings, often congregating near nests in the moments prior to emergence. When feeding on eggs crabs rupture eggshells using the sharp tips of their claws, with tissue subsequently moved to the mouthparts for ingestion using the minor claw while the broken shell is held with the major claw. When feeding on hatchlings crabs generally restrain hatchlings using the large claw to grip them around the neck, while the small claw cuts through the soft skin around the neck to partially or fully sever the head before feeding from the cavity. Infrared videography was successfully used to observe cryptic prey handling and feeding behaviours that may be compromised by more traditional observational methods.