Ghost crabs are semiterrestrial
crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
s of the
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 subfamily botanical names with "-oideae", and zoologi ...
Ocypodinae. They are common shore crabs in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
regions throughout the world, inhabiting deep burrows in the
intertidal zone
The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...
. They are
generalist
A generalist is a person with a wide array of knowledge on a variety of subjects, useful or not. It may also refer to:
Occupations
* a physician who provides general health care, as opposed to a medical specialist; see also:
** General pract ...
scavenger
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 b ...
s and
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s of small animals. The name "ghost crab" derives from their
nocturnality
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
and their generally pale coloration.
They are also sometimes called sand crabs, though the name refers to
various other crabs that do not belong to the subfamily.
Characteristics of the subfamily include one claw being larger than the other, thick and elongated eyestalks, and a box-like body. The differences in claw sizes, however, are not as marked as in male
fiddler crab
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexual dimorphism, sexually dimorphic claws; the males' major claw is much larger than th ...
s. The subfamily includes 22
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 ...
in two
genera
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 nomenclat ...
.
Taxonomy
Ocypodinae is one of two
subfamilies
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 subfamily botanical names with "-oideae", and zoologi ...
in the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
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 ...
, the other being the fiddler crab subfamily,
Ucinae
The fiddler crab or calling crab may be any of more than one hundred species of semiterrestrial marine crabs in the family Ocypodidae, well known for their sexually dimorphic claws; the males' major claw is much larger than the minor claw, while ...
. Both subfamilies have members in which one of the claw-bearing legs (the
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) is much larger than the other. However, only male fiddler crabs exhibit this, while both male and female ghost crabs have unequally sized claws. The difference is also much more pronounced among fiddler crab males. The fiddler crabs'
carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
s are broadened at the front, while the carapaces of ghost crabs are more or less box-like. Lastly, the eyes of ghost crabs have large and elongated eyestalks, with the
cornea
The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power ...
s occupying the entire lower part, while in fiddler crabs the eyestalks are long and thin, with the corneas small and located at the tip.
Ocypodinae was previously regarded as
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...
, with only one 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 female ...
'', classified under it. In 2013, though, Katsushi Sakai and Michael Türkay reclassified the
gulf ghost crab
The gulf ghost crab, ''Hoplocypode occidentalis'', is a species of ghost crabs native to the Pacific coast of the Americas, from the Gulf of California to Colombia. It is the only species in the genus ''Hoplocypode''. Gulf ghost crabs are medium ...
into a separate genus, ''
Hoplocypode
The gulf ghost crab, ''Hoplocypode occidentalis'', is a species of ghost crabs native to the Pacific coast of the Americas, from the Gulf of California to Colombia. It is the only species in the genus ''Hoplocypode''. Gulf ghost crabs are medium ...
'' 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 millip ...
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 female ...
''.
Genera
The subfamily Ocypodinae currently contains 22 species in these two genera:
*''
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 ...
''
Weber
Weber (, or ; German: ) is a surname of German origin, derived from the noun meaning " weaver". In some cases, following migration to English-speaking countries, it has been anglicised to the English surname 'Webber' or even 'Weaver'.
Notable pe ...
, 1795
*''
Hoplocypode
The gulf ghost crab, ''Hoplocypode occidentalis'', is a species of ghost crabs native to the Pacific coast of the Americas, from the Gulf of California to Colombia. It is the only species in the genus ''Hoplocypode''. Gulf ghost crabs are medium ...
''
Sakai
is a city located in Osaka Prefecture, Japan. It has been one of the largest and most important seaports of Japan since the medieval era. Sakai is known for its keyhole-shaped burial mounds, or kofun, which date from the fifth century and incl ...
& Türkay, 2013
Description
![Ghost crab - Ocypode gaudichaudii](https://upload.wikimedia.org/wikipedia/commons/6/6d/Ghost_crab_-_Ocypode_gaudichaudii.jpg)
Most ghost crabs have pale-colored bodies that blend in well with the sand,
though they are capable of gradually changing body coloration to match their environments and the time of day.
Some species are brightly colored, such as ''
Ocypode gaudichaudii
''Ocypode gaudichaudii'', also known as the painted ghost crab or cart driver crab, is a species of crab found on Pacific beaches from El Salvador to Chile as well as on the Galápagos Islands. The species was first described by Henri Milne-E ...
'' and ''
Ocypode ryderi''.
Ghost crabs have elongated and swollen eyestalks with very large corneas on the bottom half. Their carapaces are deep and box-like, squarish when viewed from the top with straight or slightly curving sides. The regions of the carapace are usually not clearly defined. The "whip" of their
antennule
Antennae ( antenna), sometimes referred to as "feelers", are paired appendages used for sensing in arthropods.
Antennae are connected to the first one or two segments of the arthropod head. They vary widely in form but are always made of one o ...
s (antennular flagella) are small or rudimentary. They fold back into the body diagonally or almost vertically. The plate between them (the interantennular septum) is broad. The third pair of mouth appendages (
maxilliped
An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body.
In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including anten ...
s) completely cover the mouth opening. A small orifice with edges thickly fringed with hair is found between the bases of the second and third pairs of walking legs.
![Ocypode brevicornis stridulating ridge](https://upload.wikimedia.org/wikipedia/commons/7/7a/Ocypode_brevicornis_stridulating_ridge.jpg)
Ghost crab species can be most reliably identified by means of the area where they were recovered, the presence of "horns" (styles) on their eyestalks (exophthalmy), the pattern of
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 inside surface of the palms of their larger claws, and the shape of the gonopods in males.
Exophthalmy is exhibited by seven species in the subfamily: ''
Ocypode brevicornis
''Ocypode brevicornis'' is a species of ghost crab native to the Indian Ocean, 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 ...
'', ''
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 Barrier ...
'', ''
Ocypode gaudichaudii
''Ocypode gaudichaudii'', also known as the painted ghost crab or cart driver crab, is a species of crab found on Pacific beaches from El Salvador to Chile as well as on the Galápagos Islands. The species was first described by Henri Milne-E ...
'', ''
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 mortoni'', ''Ocypode rotundata'', and ''Ocypode saratan''. All of them are found in the Indo-Pacific region with more or less limited ranges, with the exception of ''Ocypode ceratophthalma'', which is found widely. ''
Ocypode cursor'', found in the
Atlantic
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
and the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
, also possesses a tuft of bristles at the end of its eyestalks.
Stridulating ridges also differ from species to species, with some displaying rows of tubercles, others displaying rows of smaller ridges (striae), or a combination of both. These are very important in identifying species as they are displayed by both adults and juveniles (though they may be absent in newly regenerated claws). They are used by ghost crabs for communication.
Both exophthalmy and stridulating ridges, however, can not be reliably used to determine
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
relationships between different species of ghost crabs. Sakai & Türkay (2013) regarded the shape of the gonopods as more suited for this. As gonopods are important in sexual reproduction, they are less likely to evolve randomly in response to the environment. Ghost crabs of the genus ''Hoplocypode'' can be distinguished from those in ''Ocypode'' by examining their gonopods. In the former, the first gonopod has a complex, hoof-shaped tip, while in the latter they are simple and curved.
Ecology
![Ocypode madagascariensis](https://upload.wikimedia.org/wikipedia/commons/c/cb/Ocypode_madagascariensis.jpg)
Ghost crabs dig deep
burrow
An Eastern chipmunk at the entrance of its burrow
A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of locomotion. Burrows provide a form of sh ...
s near the
intertidal zone
The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...
of open sandy beaches. The burrows are usually composed of a long shaft with a chamber at the end, occasionally with a second entrance shaft.
They are semi-terrestrial and breathe oxygen from the air through moistened
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...
s. They must periodically wet their gills with
seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has appro ...
,
usually by taking water from moist sand or by running into the surf and letting the waves wash over them. However, they can only remain under water for a limited amount of time, as they will drown.
Ghost crabs 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 be ...
carrion
Carrion () is the decaying flesh of dead animals, including human flesh.
Overview
Carrion is an important food source for large carnivores and omnivores in most ecosystems. Examples of carrion-eaters (or scavengers) include crows, vultures, c ...
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
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
on small animals, including
sea turtle
Sea turtles (superfamily Chelonioidea), sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the flatback, green, hawksbill, leatherback, loggerhead, ...
eggs and
hatchling
In oviparous biology, a hatchling is a newly hatched fish, amphibian, reptile, or bird. A group of mammals called monotremes lay eggs, and their young are hatchlings as well.
Fish
Fish hatchlings generally do not receive parental care, similar to ...
s,
clams
Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...
, and other crabs. They are predominantly
nocturnal
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.
Nocturnal creatures generally have highly developed sens ...
. They remain in their burrows during the hottest part of the day, and throughout the coldest part of the winter.
Ghost crabs are swift runners, darting away at the slightest sign of danger. They either head back to their burrows or plunge into the sea to escape intruders.
The
gait
Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. Di ...
s of ghost crabs alter as their speed increases. Observations on ''O. ceratophthalma'' show it can walk indefinitely using all four pairs of walking legs, occasionally alternating which side leads. At higher speeds, the fourth pair of legs is raised off the ground, and at the highest speeds, the crab
runs, using only the first and second pairs of walking legs.
Ghost crabs utilize a varied animal acoustic communication system. They can create different sounds by striking the ground with their claws, rubbing their claws together to make a rasping sound, rubbing their legs to make a bubbly noise, and rubbing the teeth inside their stomachs to make a growling sound. The lateral teeth of the gastric mill possess a series of comb-like structures that rub against the median tooth to produce stimulation with dominant frequencies below 2 kHz.
Ghost crabs also have the ability to change
color
Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...
s to match their surroundings by adjusting the concentration and dispersal of pigments within their
chromatophore
Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and ...
s.
They can even match the specific colors of the grains of sand in their habitats.
However, unlike
metachrosis (which is a rapid change of colors), ghost crabs are only capable of morphological color change, which occurs over a longer span of time.
File:Ocypode quadrata (Cahuita).jpg, Atlantic ghost crab (''Ocypode quadrata
The Atlantic ghost crab, ''Ocypode quadrata'', is a species of ghost crab. 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 re ...
'') emerging from its burrow in Cahuita, Costa Rica
Costa Rica (, ; ; literally "Rich Coast"), officially the Republic of Costa Rica ( es, República de Costa Rica), is a country in the Central American region of North America, bordered by Nicaragua to the north, the Caribbean Sea to the no ...
File:Ocypode ceratophthalma (Kauai, Hawaii).jpg, Horned ghost crab (''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 Barrier ...
'') from a black sand beach in Kauai
Kauai, () anglicized as Kauai ( ), is geologically the second-oldest of the main Hawaiian Islands (after Niʻihau). With an area of 562.3 square miles (1,456.4 km2), it is the fourth-largest of these islands and the 21st largest island ...
File:Starr 031007-2031 Ocypode ceratophthalmus.jpg, White sand beach in Kahoolawe
Kahoolawe (Hawaiian: ), anglicized as Kahoolawe (), is the smallest of the eight main volcanic islands in the Hawaiian Islands. Kahoolawe is located about southwest of Maui and also southeast of Lānaʻi, and it is long by wide, with a total ...
, Hawaii
Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
File:Sand Crab carrying eggs in Cancun Mexico (Ocypodidae).jpg, Sand Crab carrying eggs in Cancun Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
(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 ...
)
In a study in 1964, individuals of ''O. ceratophthalma'' in Hawaii from two populations (one from a black-sand beach and the other from a white-sand beach) were observed to markedly differ in pigmentation although they remain morphologically indistinguishable. Specimens taken from the black-sand beach were much darker than the specimens taken from the white-sand beach, exhibiting nearly 12 times as many black chromatophores. When the black-sand specimens were subsequently exposed to a white background, they were observed to gradually become lighter over the course of about a month. The opposite happened to white-sand specimens when placed in black backgrounds.
![110127 Running ghost crab O ceratophtalma prey Loggerhead hatchling Gnaraloo Bay Rookery](https://upload.wikimedia.org/wikipedia/commons/6/60/110127_Running_ghost_crab_O_ceratophtalma_prey_Loggerhead_hatchling_Gnaraloo_Bay_Rookery.JPG)
In a 2013 study in
Singapore
Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...
, ''Ocypode ceratophthalma'' was also discovered to change color in response to the time of day. In a span of 24 hours, they were observed to alternate between lighter and darker coloration, being lightest at midday and darkest at night. However, when placed in a dark background, the crabs showed no significant changes in coloration. This suggests, at least for short-term color changes, they follow a day-night cycle to determine body coloration; basing it on their
biological clocks rather than on the brightness or darkness of their environments. The researchers believe relying on the time of day rather than ambient light is more advantageous for survival in ghost crabs. It lets ghost crabs avoid changing color when in temporary shadow (for example within their burrows) and thus still remain inconspicuous when they are once again illuminated by daylight. However, this behavior is only exhibited by juveniles.
Ghost crabs lay their
eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
in the sea, which develop into
plankton
Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...
ic marine
larvae
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
.
Distribution
Ghost crabs dominate sandy shores in
tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...
regions of the world, replacing the
sandhopper
Talitridae is a family of amphipods. Terrestrial species are often referred to as landhoppers and beach dwellers are called sandhoppers or sand fleas. The name sand flea is misleading, though, because these talitrid amphipods are not siphonapter ...
s that predominate in cooler areas.
Three species are found in the
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
and the
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...
, and two occur in the eastern
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 definition, to Antarctica) in the south, and is bounded by the continen ...
coast of the Americas. The rest of the species are found in the western Pacific and 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 th ...
to the tip of southern
Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...
.
Conservation
Ghost crabs are negatively affected by human activity on sandy beaches, such as sand trampling by foot traffic, the building of
seawall
A seawall (or sea wall) is a form of coastal defense constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservation ...
s, or the presence of inorganic pollutants. Due to their worldwide distribution and the ease by which their burrows can be surveyed, ghost crab burrows are regarded as valuable
ecological indicator
Ecological indicators are used to communicate information about ecosystems and the impact human activity has on ecosystems to groups such as the public or government policy makers. Ecosystems are complex and ecological indicators can help describe ...
s for quickly assessing the impact of human disturbance on beach habitats.
See also
*''
Heloecius'' - the semaphore crab
References
[Taylor, Jennifer R. A., et al. “Growling from the Gut: Co-Option of the Gastric Mill for Acoustic Communication in Ghost Crabs.” Proceedings of the Royal Society B: Biological Sciences, vol. 286, no. 1910, 2019, p. 20191161., doi:10.1098/rspb.2019.1161.]
External links
* Taylor, Jennifer R. A., et al. “Growling from the Gut: Co-Option of the Gastric Mill for Acoustic Communication in Ghost Crabs.” Proceedings of the Royal Society B: Biological Sciences, vol. 286, no. 1910, 2019, p. 20191161., doi:10.1098/rspb.2019.1161.
*
*
Videoof ''Ocypode ceratophthalma'' eating a moon crab in
Saint John's Island
Saint John's Island also known as Saint John's is the largest of the Southern Islands in Singapore. Its indigenous Malay name is Pulau Sekijang Bendera. It is located approximately 6.5 km to the south of the main island of Singapore, off th ...
,
Singapore
Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...
{{Taxonbar, from=Q932818
Ocypodoidea