''Ocypode brevicornis'' is a
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
ghost crab
Ghost crabs are semiterrestrial crabs of the subfamily Ocypodinae. They are common shore crabs in tropical and subtropical regions throughout the world, inhabiting deep burrows in the intertidal zone. They are generalist scavengers and predators ...
native to the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...
, from the
Gulf of Oman to the
Nicobar Islands. They are relatively large ghost crabs with a somewhat trapezoidal body. The
carapace reaches a length of and a width of . They are a mottled brown to yellow in coloration. Like other ghost crabs, one of their claws is much larger than the other. Their eyestalks are large and elongated, tipped with prolongations at the tip known as styles. They are common inhabitants of open sandy beaches, living in burrows in the
intertidal zone.
Taxonomy
''Ocypode brevicornis'' was first described by the French
zoologist
Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and d ...
Henri Milne-Edwards in 1837. However, his
type specimen
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes th ...
s consisted only of two juvenile individuals from
Pondicherry
Pondicherry (), now known as Puducherry ( French: Pondichéry ʊdʊˈtʃɛɹi(listen), on-dicherry, is the capital and the most populous city of the Union Territory of Puducherry in India. The city is in the Puducherry district on the sout ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
. In 1852, he again described the same species from adult specimens recovered from the same area as ''Ocypode platytarsis''. In 1880, the American zoologist
John Sterling Kingsley synonymized ''Ocypode brevicornis'' with ''
Ocypode ceratophthalma
''Ocypode ceratophthalmus'', the horned ghost crab or horn-eyed ghost crab, is a species of ghost crab. It lives in the Indo-Pacific region (except the Red Sea); from the coast of East Africa to the Philippines and from Japan to the Great Barr ...
''. As a result, only ''Ocypode platytarsis'' was regarded as
valid for the entirety of the 20th century. And most literature concerning the species refer to it as ''Ocypode platytarsis''. In 2013, the Japanese
carcinologist Katsushi Sakai and German carcinologist Michael Türkay discovered that the type specimens of ''Ocypode brevicornis'' and ''Ocypode platytarsis'' belonged to the same species. They restored the validity of the earlier name ''Ocypode brevicornis''.
''Ocypode brevicornis'' has also been frequently confused with ''Ocypode ceratophthalma'', due to the fact that both species possess elongations of their eyestalks (styles). The variety ''Ocypode brevicornis'' var. ''longicornuta'' described by the American zoologist
James Dwight Dana
James Dwight Dana FRS FRSE (February 12, 1813 – April 14, 1895) was an American geologist, mineralogist, volcanologist, and zoologist. He made pioneering studies of mountain-building, volcanic activity, and the origin and structure of continent ...
is now known to be a synonym of ''Ocypode ceratophthalma''.
''Ocypode brevicornis'' belongs to the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''
Ocypode
''Ocypode'' is a genus of ghost crabs found in the sandy shores of tropical and subtropical regions throughout the world. They have a box-like body, thick and elongated eyestalks, and one claw is larger than the other in both males and female ...
'' of the ghost crab
subfamily Ocypodinae in the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Ocypodidae
The Ocypodidae are a family of semiterrestrial crabs that includes the ghost crabs and fiddler crabs. They are found on tropical and temperate shorelines around the world.
Some genera previously included in the family are now treated as members o ...
.
Description
''Ocypode brevicornis'' are large ghost crabs with deep bodies.
The
carapace in adults ranges from in length, and in width.
It is almost
trapezoid
A quadrilateral with at least one pair of parallel sides is called a trapezoid () in American and Canadian English. In British and other forms of English, it is called a trapezium ().
A trapezoid is necessarily a convex quadrilateral in Eu ...
al in shape, with the rear end distinctly narrower than the front. It is wider than it is long and covered with scattered rough bumps (tubercles). The upper margins of the eye sockets slant forwards on the inner half and backwards for the outer half. The edges of the eye sockets are rectangular.
The eyestalks are large and swollen with the cornea occupying most of the bottom half. The eyestalks exhibit prolongations (styles) on the tips like some other members of the genus. The styles may be absent or much shorter in juvenile specimens,
as it only starts growing when the crab is around in length.
![Ocypode brevicornis stridulating ridge](https://upload.wikimedia.org/wikipedia/commons/7/7a/Ocypode_brevicornis_stridulating_ridge.jpg)
Like other ghost crabs, one of the claw appendages (
cheliped
A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. ...
s, the first
pereiopod pair) of ''Ocypode brevicornis'' is much bigger than the other. The palm of the larger cheliped is long with a rough bumpy texture on the upper surface. The upper edges of the palm are covered with small bumps while the bottom edge is serrated. 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. In ''Ocypode brevicornis'', the stridulating ridge is composed of a row of 23 to 28 tubercles. The smaller cheliped tapers towards a pointed end.
The first
gonopod
Gonopods are specialized appendages of various arthropods used in reproduction or egg-laying. In males, they facilitate the transfer of sperm from male to female during mating, and thus are a type of intromittent organ. In crustaceans and millipe ...
(appendages modified into sexual organs) of the male is stem-like. Its cross-section has three sides on the base ending in a slightly curving tip. A broad and flat palp is present. The covering (operculum) of the female genital opening is oriented lengthwise with a thick straight rim slanting backwards.
Adult ''Ocypode brevicornis'' are a mottled yellow to brown in coloration. Males have been observed to display brighter yellow colors, especially on their legs. Juveniles have almost perfect
cryptic camouflage, making it very difficult to pick them out from their surroundings.
Ecology
Like other ghost crabs, ''Ocypode brevicornis'' live in deep burrows near the
intertidal zone of open sandy beaches.
They are
generalists,
scavenging
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding ...
carrion and
debris
Debris (, ) is rubble, wreckage, ruins, litter and discarded garbage/refuse/trash, scattered remains of something destroyed, or, as in geology, large rock fragments left by a melting glacier, etc. Depending on context, ''debris'' can refer to ...
as well as
preying on small animals.
They are primarily
nocturnal, though they may emerge during the day. They are swift runners, darting away to their burrows at the slightest sign of danger, even when the intruder sighted is still away. However, they can be approached much more closely at night, though they may still try to escape if illuminated.
Males of ''Ocypode brevicornis'' exhibit elaborate territorial displays. Like other ghost crabs, they produce sound and vibration by rapping their larger claws against the ground. They may also display "dances" on the approach of another ghost crab. Beginning with a rearing posture, the males conduct increasingly complex sideways movements ending by running around the intruder in circles until it retreats.
Distribution
''Ocypode brevicornis'' are restricted to the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by t ...
. They can be found from the
Gulf of Oman to
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
,
Sri Lanka, and the
Nicobar Islands. They are one of six ghost crab species found in the
Indian subcontinent
The Indian subcontinent is a list of the physiographic regions of the world, physiographical region in United Nations geoscheme for Asia#Southern Asia, Southern Asia. It is situated on the Indian Plate, projecting southwards into the Indian O ...
, the others being ''
Ocypode ceratophthalma
''Ocypode ceratophthalmus'', the horned ghost crab or horn-eyed ghost crab, is a species of ghost crab. It lives in the Indo-Pacific region (except the Red Sea); from the coast of East Africa to the Philippines and from Japan to the Great Barr ...
'', ''
Ocypode cordimanus'', ''
Ocypode macrocera
''Ocypode'' is a genus of ghost crabs found in the sandy shores of tropical and subtropical regions throughout the world. They have a box-like body, thick and elongated eyestalks, and one claw is larger than the other in both males and female ...
'', ''
Ocypode pallidula'', and ''
Ocypode rotundata
''Ocypode rotundata'' is a large-sized species of ''Ocypode'' found in the southern coast of the Arabian Peninsula to northern India (from Oman to Bombay), including the Persian Gulf
The Persian Gulf ( fa, خلیج فارس, transl ...
''.
See also
*''
Heloecius'' - the semaphore crab
References
External links
*
{{Taxonbar, from=Q13908723
Ocypodoidea
Crustaceans described in 1837
Crustaceans of Sri Lanka
Crustaceans of Asia
Taxa named by Henri Milne-Edwards