Golden ghost crab

Golden ghost crabs are common inhabitants of open sandy beaches, living in burrows in the intertidal and supratidal zones.

[note 1] The type specimens were recovered from Dirk Hartog Island, Shark Bay, Western Australia, during the circumnavigational voyage of the French corvettes Uranie and Physicienne (1817–1820) under the command of Louis de Freycinet.

The latter is a direct translation of Quoy and Gaimard's "French name" of the species, Ocypode bombé, referring to the dome-like shape of the carapace.

[9] The species was more widely known in scientific literature by its junior synonym Ocypode pygoides in the early 20th century due to the uncertainty regarding the original descriptions and illustrations by Quoy and Gaimard.

[1][11] In 1894, the Prussian-American zoologist Arnold Edward Ortmann described Ocypode pygoides without consulting Quoy and Gaimard's original work.

This ruling was made on the basis that the consulted specialists regarded Quoy and Gaimard's Ocypode convexus as nomen dubium.

In 1902, the Dutch biologist Johannes Govertus de Man recognised that it was actually a new species and named it Ocypode nobilii in honour of Nobili.

Their tips do not extend into a spike (style) making them easy to distinguish from the similarly-sized horned ghost crab (Ocypode ceratophthalma) which also occurs in Western Australia.

[1][8] The palm (propodus)[note 5] of both larger and smaller chelipeds are covered coarsely with large irregularly-arranged tubercles on the outer surface, giving them a rough appearance.

The inner surface of the palm of the larger claw in both sexes features stridulating (sound-producing) ridges, which is important for identifying different species within the subfamily Ocypodinae.

[6] They must periodically wet their gills with seawater, usually by taking water from moist sand or by running into the surf and letting the waves wash over them.

[5] However, in 1962, the Australian zoologist William Ride reported golden ghost crabs foraging inland as far as 500 m (1,600 ft) away from the sea following heavy rains.

[5] Golden ghost crabs live in deep burrows in the intertidal and supratidal zones of open sandy beaches.

[5] In the presence of potential threats (like humans), golden ghost crabs have been observed to only raise one eyestalk at a time, keeping the other one protected within its eye orbit.

[6] They scavenge carrion and debris like dead fish or seaweed washed up by the waves; as well as prey on small animals like molluscs, other crustaceans, and sea turtle hatchlings.

[22][23] Aside from directly preying on emerging hatchlings heading towards the water, there are also indications that golden ghost crabs actively burrow into nesting sites and feed on turtle eggs.

However, gauging the true extent of the effects of golden ghost crabs on sea turtle hatchling and egg mortality still remains difficult, largely due to the fact that they usually flee at the presence of human observers and thus skew the data.

[1] Due to the limited range of golden ghost crabs in Western Australia, they are deemed vulnerable to large scale environmental disasters that might affect the region (like oil spills).

[25][26] Golden ghost crabs, however, remain abundant in places with little to no human habitation, particularly in beaches with restricted vehicular access (such as the Gnaraloo Station).

Jean René Constant Quoy and Joseph Paul Gaimard 's original 1824 illustration of Ocypode convexa [ 3 ]
Ocypode convexa eyestalks and anterior profile of the carapace ( top ); and the stridulating ridge (a row of 19 to 24 tubercles) on the larger claw ( bottom ). [ 1 ] [ 11 ]
Golden ghost crabs eating a dead octopus
A golden ghost crab preying on a loggerhead sea turtle ( Caretta caretta ) hatchling at Gnaraloo , Western Australia
A golden ghost crab on a marked sea turtle nest
Antagonistic encounter between a golden ghost crab and a horned ghost crab ( Ocypode ceratophthalma )