Ocypode quadrata

From AU Science Wiki
Jump to: navigation, search

Ocypode quadrata- Atlantic Ghost Crab, characterized by Phillips (1940) as “an occult, secretive alien from the ancient depths of the sea.”

Ghost crab.jpg

Range-It is a common species along the Atlantic coast of the United States, where it is the only species of ghost crab; its range of distribution extends from its northernmost reach on Rhode Island's beaches south along the coasts of the tropical Western Atlantic Ocean to the beach of Barra do Chui, in Rio Grande do Sul in Southern Brazil. O. quadrata is found from Block Island, Rhode Island to Santa Catarina, Brazil, on Fernando de Noronha and Bermuda. Its planktonic larvae have been found even further north, at Woods Hole, Massachusetts, although the adults cannot survive there.

Description- Adults are greyish or the colour of straw, and approximately 5 centimetres (2 in) wide at maturity. They must return to water periodically in order to moisten their gills, and when larvae must be released into the sea, but are otherwise terrestrial. It can also moisten its gills by extracting water from damp sand, using fine hairs near the base of its walking legs to wick ground water up onto the gills through capillary action. Their stalked compound eyes can swivel to give them 360° vision.Young crabs are cryptically coloured to blend in with their sandy habitat.

Ecological Notes- These crabs live in burrows along the high tide line. The older a crab becomes the further away from the sea it can live, the furthest being nearly 400M away from the Ocean edge. The Ghost Crab is a nocturnal hunter, emerging at night to feed on clams, insects, plant material, detritus, and even other crabs (Mainly the Mole Crab). These crabs can also produce a myriad of sounds mainly used for mating rituals by males. They produce these sounds by striking the ground with the claw, by stridulation with the legs, and an unexplained "bubbling sound". Mating rituals between males have become so ritualistic that there is almost no need for physical contact between the crabs.

Personal Information- During summer nights these crabs come out in great numbers to feed. During the winter they stay in their burrows and hibernate. The main habitat of these crabs, sandy beaches, are heavily impacted by human and vehicle trampling. This compression of the sand leads to direct crushing or the crabs, and reduces habitat suitability, reduction of food supply, interference with mating rituals. While they are not currently listed as endangered or threatened, these crabs are usually more frequent on beaches less visited by people.

Journal Articles- To learn more about the Atlantic Ghost Crab, Check out these Journal Articles

== Phillips A.M. 1940. The ghost crab – adventures investigating the life of a curious and interesting creature that lives on our doorstep, the only large crustacean of our North Atlantic coast that passes a good part of its life on land. Natural History. 46:36-41. == This Paper, although written a long time ago, is a good first look into the ghost crab as a species. This is the first real description of the Alantic Ghost Crab.

== Wolcott, T.G. 1978. Ecological role of ghost crabs, Ocypode quadrata (Fabricius) on an ocean beach: scavengers or predators? Journal of Experimental Marine Biology and Ecology. 31:67-82. == This article reviews the life of the Atlantic Ghost Crab, and goes over their feeding habits in order to determine if the Ghost crab was more of a scavenger or an active hunter

References Knott, David. "Atlantic Ghost Crab Ocypode quadrata." Department of Natural Resources, South Carolina. (2006): n. page. Web. 24 Apr. 2012. [<http://www.dnr.sc.gov/cwcs/pdf/Ghostcrab.pdf>].