Atlantic Ghost Crab
Ocypode quadrata
Summary 5
Ocypode quadrata, known as the Atlantic ghost crab, is a species of ghost crab, once described as an "occult, secretive alien from the ancient depths of the sea". 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...
Comprehensive description 6
Atlantic Ghost Crabs (Ocypode quadrata) are small crabs (up to around 50 mm) with squarish sand-colored shells having margins that are finely beaded but toothless; the claws are white. The space between the eyes is much shorter than the eyestalks. These crabs dig burrows above the intertidal zone on ocean beaches from Delaware (U.S.A.) through the Caribbean and Gulf of Mexico to Brazil. They are occasionally found north to eastern Long Island and Rhode Island, but are uncommon north of Virginia. Atlantic Ghost Crabs are very active and can often be seen dashing into the retreating surf to wet their gills or to grab scraps of food ("Ocypode" means "swift-footed"), although they will drown if kept submerged. Young crabs burrow just above the intertidal zone, but adults dig their burrows higher up, sometimes even behind the forward dunes. Burrows have a single opening and descend 0.6 to 1.2 meters at a 45 degree angle. Although these crabs are often out and about during the day, they are most active at night. (Gosner 1978)
Physical description 7
Ocypode quadrata is small, having a carapace length of about 5 cm (2 inches) at maturity. They are either straw-colored or grayish-white. They have a quadrate carapace, large club-shaped eyestalks, unequal chelipeds (claws) and long walking legs. Males are generally larger than females.
Average length: 50 mm.
Other Physical Features: bilateral symmetry
Sexual Dimorphism: male larger
Habitat 8
Ghost crabs inhabit tropical and subtropical areas and can be found on both oceanic and more protected estuarine beaches. They are found on the supralittoral zone (the area above the spring high tide line) of sand beaches, from the water line up to the dunes.
Range elevation: 0 to 3.05 m.
Average elevation: 2 m.
Habitat Regions: tropical ; saltwater or marine
Aquatic Biomes: coastal
Other Habitat Features: estuarine ; intertidal or littoral
Communication and perception 9
Ghost crabs communicate using many sounds, including striking the ground with their claws, stridulation (rubbing together) of their legs and making a “bubbling sound”. Males compete in a ritualized matter that avoids the need for physical contact.
Communication Channels: acoustic
Development 10
After hatching from an egg, Ocypode quadrata has five zoea stages and one megalopa stage. The megalopa stage requires at least 35 days for development. The larvae develop in saline water. The megalopa stage of Ocypode quadrata is one of the largest of the brachyuran crabs. Metamorphosis into the first crab stage takes place at the surf-beach interface.
Development - Life Cycle: metamorphosis
Reproduction 11
Mating can occur throughout the year. Unlike other crab species, ghost crabs can mate even when the female’s integument is hard, which means that they can mate anytime after sexual maturation. This is an adaptation to terrestrial life. Mating occurs while both the male and the female have a hard shell. Usually mating will occur somewhere in or near the burrow of the male. Often copulatory plugs are found in ghost crabs; the male will release a seminal fluid along with his sperm that will become hard and prevent rival sperm from reaching the female’s ova.
Mating System: monogamous
In the Carolinas, ghost crabs spawn from April through July. Females will mature and ovulate in April and again in August. Females reach sexual maturity when their carapace is larger than 25 mm. Males reach sexual maturity when their carapace is larger than 24 mm. This usually occurs when they are about a year old.
Breeding season: Mating occurs throughout the year.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: year-round breeding ; sexual
The female will carry the eggs beneath her body, which will be released into the surf. While carrying the eggs, she must keep them wet by frequently entering the water. Some females may turn upside down in the water to ventilate their eggs.
Parental Investment: female parental care ; pre-hatching/birth (Protecting: Female)
Link to Access Genomic Data 12
http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=53310&lvl=0
Sources and Credits
- (c) Jose Nunez, some rights reserved (CC BY-NC-ND), uploaded by Jose Nunez
- (c) Terry Ross, some rights reserved (CC BY-SA), http://www.flickr.com/photos/78272611@N00/3866409910
- (c) Fabio Moretzsohn, some rights reserved (CC BY-NC), uploaded by Fabio Moretzsohn
- (c) Arthur Chapman, some rights reserved (CC BY-NC-SA), http://farm4.static.flickr.com/3185/3027248682_344e2929b9_o.jpg
- Adapted by matbio from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Ocypode_quadrata
- Adapted by matbio from a work by (c) Shapiro, Leo, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/17763406
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18662603
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18662602
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18662607
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18662604
- (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/18662605
- (c) Emily Rose Sharkey, all rights reserved
