Ghost CrabOcypode sp.
Category
- Sandy Beach & Dunes
General description
Ghost crabs (Ocypode species) are commonly found on sandy beaches. They are distinguished by their box-shaped bodies, thick and elongated eyestalks, and one claw larger than the other in both males and females.[1] Their carapace colour ranges from pale pink to cream and help them blend with the sand. They are fast moving animals, and if spotted during the day, they will rapidly burrow in their holes, however, they are primarily nocturnal animals. Ghost crab species found in Mauritius and Bel Ombre include Ocypode pallidula, Ocypode ceratophtalma, and Ocypode cordimanus.
[1] Richmond, Matthew (ed.). 2011. A fieldguide to the seashores of Eastern Africa and the Western Indian Ocean islands. Sida/WIOMSA.
Habitat and ecology
Ghost crabs are mostly nocturnal animals and are scavengers, although some Ocypode species are also known to occasionally feed on bivalve molluscs. They live in the littoral fringe of sandy shores that are exposed to the sea. They construct deep and complex burrows which protect them from predators, extremes weather and allow them to stay in a moist environment avoiding desiccation in the scorching sun. They alternate between surface activity where they may forage, mate or disperse and their underground habitats. In the food chain, they are apex invertebrate consumers and are eaten by birds or mammals. Male ghost crabs perform various courtship rituals which include sounds or building sand mounds. After copulation, eggs hatch after 43 days, then the females will release the larvae in the water at night.
Conservation status and threats
The IUCN status for this species is unknown. Ghost crabs are not currently considered threatened. However, they suffer from the consequences of human activity on beaches such as trampling by foot, coastal development, pollution as well as beach erosion. Density of ghost crabs on beaches and dunes has been considered as a useful indicator of human disturbance on exposed sandy beaches.
Did you know?
Ghost crabs can change their colour to match their surroundings by adjusting the concentration and dispersal of pigments within their chromatophores.[1]
[1] Lucrezi, Serena , Thomas A. Schlacher , and Wayne Robinson. 2009. "Human disturbance as a cause of bias in ecological indicators for sandy beaches: Experimental evidence for the effects of human trampling on ghost crabs (Ocypode spp.)." Ecological Indicators 9 (5): 913-921.
