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The Robinson Library >> Science >> Zoology >> Crustaceans >> Subclass Decapoda
Atlantic Ghost Crab

Ocypode quadrata

Description

The ghost crab is so named because its straw to grayish-white color allows it to practically disappear into the sand, an effect made even more possible by its ability to slightly change its color as needed. That camouflage ability is slightly offset, however, by the ghost crab's conspicuous white claws and large club-shaped eyestalks (which can rotate 360 degrees). Young ghost crabs are darker than adults, but have markings that help them "blend into" the sand.

The square-shaped carapace is about 2-3 inches long, with males being larger than females.

Atlantic ghost crab

Distribution and Habitat

The Atlantic ghost crab is found along the Atlantic coast of North and South America, from Rhode Island to Brazil, as well as in Bermuda. Although its larvae have been found in the waters off Massachusetts, adults cannot survive that far north. It inhabits both oceanic and protected estuarine beaches, above the spring high tide line.

Diet

Like most other crabs, ghost crabs are both predators and scavengers, with their primary food being influenced by the type of beach they live on. Crabs on oceafront beaches, for example, tend to feed on clams and smaller crabs, while those on more protected beaches dine on turtle eggs and hatchlings. They also feed on insects, plant matter, and detritus.

Reproduction

Mating can occur throughout the year. Unlike other crab species, ghost crabs can mate even when the female’s shell is hard, which is an adaptation to terrestrial life. How mating pairs are formed is unknown, but the male often releases a fluid with his sperm that hardens and prevents another male's sperm from reaching the female's ova. The female will carry the eggs beneath her body before releasing them into the surf. While carrying the eggs, she must keep them wet by frequently entering the water, and she may turn upside down in the water to ventilate them.

Other Information

The ghost crab is primarily nocturnal, further "justifying" its name. It spends the day in a burrow up to four feet deep. Younger ghost crabs burrow close to the water, while older ghost crabs often burrow hundreds of feet from the water's edge. Because it may travel up to 980 feet or more while foraging at night, a ghost crab seldom returns to the same burrow each day.

Because the ghost crab is primarily terrestrial it has developed an interesting adaptation for life on land. Although it will occasionally return to the water to wet its gills, it can also get water from damp sand by using the fine hairs on the base of its legs to wick water from the sand up onto its gills.

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.

Scientific Classification

phylum Arthropoda
subphylum Crustacea
class Malacostraca
order Decapoda
family Ocypodidae
genus & species Ocypode quadrata

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The Robinson Library >> Science >> Zoology >> Crustaceans >> Subclass Decapoda

This page was last updated on October 30, 2017.