The gulf ghost crab, ''Hoplocypode occidentalis'', is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 predator ...

s native to the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is bounded by the cont ...

coast of the

Americas The Americas, sometimes collectively called America, are a landmass comprising the totality of North America and South America.''Webster's New World College Dictionary'', 2010 by Wiley Publishing, Inc., Cleveland, Ohio. When viewed as a sing ...

, from the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

. It is the only species in the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Hoplocypode''. Gulf ghost crabs are medium-sized, reaching a maximum overall body diameter of . They are one of only two ghost crab species found in the eastern Pacific (the other being the painted ghost crabs). However, gulf ghost crabs can easily be distinguished from painted ghost crabs by the absence of "horns" on their eyes.

Taxonomy

''Hoplocypode occidentalis'' was first described by the American marine biologist

William Stimpson William Stimpson (February 14, 1832 – May 26, 1872) was an American scientist. He was interested particularly in marine biology. Stimpson became an important early contributor to the work of the Smithsonian Institution and later, director o ...

in 1860 as ''Ocypoda occidentalis''. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

s were originally collected from

Cabo San Lucas Cabo San Lucas (, "Luke the Evangelist, Saint Luke Cape (geography), Cape"), also known simply as Cabo, is a Resort town, resort city at the southern tip of the Baja California peninsula, in the Mexican Political divisions of Mexico, state of Baja ...

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. It was transferred to its own genus ''Hoplocypode'' in 2013 by Katsushi Sakai and Michael Türkay based on the differences of their

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 ...

s (appendages modified into copulatory organs) from that of the rest of the members of the genus ''

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 females ...

''. It is classified under the ghost crab

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Ocypodinae 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 ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Ocypodidae The Ocypodidae is a family of semiterrestrial crabs that includes ghost crabs and fiddler crabs. These crabs are found along tropical and temperate shorelines worldwide. Some genera previously classified within the Ocypodidae family have been r ...

. The specific name is from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

'' occidentalis'' ("western"). They are commonly known as the "gulf ghost crab" in

English English usually refers to: * English language * English people English may also refer to: Culture, language and peoples * ''English'', an adjective for something of, from, or related to England * ''English'', an Amish ter ...

and ''cangrejo de playa'' in

Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many countries in the Americas **Spanish cuisine **Spanish history **Spanish culture ...

Description

Gulf ghost crabs are medium-sized ghost crabs with deep bodies, reaching a maximum overall body diameter of . The upper surface of the body is generally dark gray with lighter colored marbling. The underside of the body, the tips of the walking legs, and the claws are creamy white. Their coloration varies, usually matching the color of the sand surrounding them, but they are easier to see on black volcanic sand and on light-colored dry sand. Hoplocypode leg

The carapace is squarish in shape and wider than it is long, with a length around and a width of . It is thickly covered with rough, small bumps (tubercles). Their eyestalks are large and elongated, but do not possess "horns" as in some other ghost crab species. The outer half of margins of the eye sockets curve distinctly inwards, with the outer edges (exorbital angles) triangular in shape with a sharp, forward-facing, pointed end. Like other ghost crabs, one of the claw appendages (

cheliped A chela ()also called a claw, nipper, or pinceris a pincer-shaped organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through Neo-Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds ...

s, the first

pereiopod The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...

pair) of gulf ghost crabs is much bigger than the other. The palm of the larger cheliped is elongated with a serrated lower edge and covered with tubercles on the upper surface. It features

stridulating Stridulation is the act of producing sound by rubbing together certain body parts. This behavior is mostly associated with insects, but other animals are known to do this as well, such as a number of species of fish, snakes and spiders. The mech ...

(sound-producing) ridges on the inner surface of the palm, which is important for identifying different species within the subfamily Ocypodinae. In gulf ghost crabs, the stridulating ridge is short and composed of a row of 21 to 22 tubercles. The smaller cheliped tapers towards a pointed end. The second pair of walking legs are not more than two and a half times the length of the carapace. The fourth pair is relatively smaller and weaker in comparison to the other three pairs, reaching only to the middle of the propodus of the third pair. The mera and

carpi Carpi may refer to: Places * Carpi, Emilia-Romagna, a large town in the province of Modena, central Italy ** Roman Catholic Diocese of Carpi * Carpi (Africa), a city and former diocese of Roman Africa, now a Roman Catholic titular see People ...

of all the legs are naked, but the propodi possess fur-like bristles (setae) on for the first three walking leg pairs varying by sex. In males, the propodi of the first and second pair of walking legs have their upper forward surfaces covered with setae. The propodi of the third pair of walking legs only have setae on the upper margin of the propodi. In females, the propodi of the third and last pair of walking legs do not possess bristles on the upper surfaces of their propodi. The first gonopods (modified copulatory organs) of males are also distinctively complex in shape, with a triangular cross-section at the base and becoming hoof-like towards the end. This characteristic is one of the diagnostic criteria for the genus. The covering (operculum) of the genital duct of the females has four sides and is membranous and slightly calcified. The genital slit is narrow and aligned along the middle of the operculum.

Ecology

Gulf ghost crabs live in burrows near the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

of open sandy beaches and on sand and silt banks near where river mouths empty into the sea. Larger individuals usually have burrows further up the shore, while smaller individuals are closer to the waves. They are

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

, emerging from their burrows just after sunset. They are fast-moving generalist

scavenger Scavengers are animals that consume Corpse decomposition, 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 he ...

s and

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

s, usually feeding on decaying bodies of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

and other

crustacea Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

ns. They are also devastating predators of eggs and hatchlings of sea turtles, including the olive Ridley sea turtle (''

Lepidochelys olivacea The olive ridley sea turtle (''Lepidochelys olivacea''), also known commonly as the Pacific ridley sea turtle, is a species of turtle in the family Cheloniidae. The species is the second-smallest and most abundant of all sea turtles found in th ...

'') and the leatherback sea turtle ('' Dermochelys coriacea''). In

Playa Grande, Costa Rica Playa Grande (, lit. "Big Beach"), also known as Salinas, is a beach community on the Pacific coast of Costa Rica just north of Tamarindo. It is located inside the canton of Santa Cruz in Guanacaste Province. Playa Grande has been part of the ...

, they've been observed to be responsible for as much as 48% of the total number of deaths in freshly hatched sea turtles crossing the beaches towards the water.

Distribution

Gulf ghost crabs are native to the eastern

coast of the Americas, from the

. They are

sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

with the painted ghost crab ('' Ocypode gaudichaudii''), and juvenile specimens of the two smaller than are very difficult to tell apart. However, the adults are readily distinguishable, as painted ghost crabs are brightly colored and possess "horns" (styles) on their eyestalks which are absent in gulf ghost crabs. Painted ghost crabs also prefer sheltered rocky beaches, while gulf coast crabs are found on open sandy beaches. Gulf ghost crabs also superficially resemble the Atlantic ghost crab ('' Ocypode quadrata''), but the two species do not occur in the same areas, with the latter being only found in the western

Atlantic The Atlantic Ocean is the second largest of the world's five oceanic divisions, with an area of about . It covers approximately 17% of Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for se ...

coast of the Americas.

References

External links