Gecarcinus ruricola
Encyclopedia
Gecarcinus ruricola is a species
of terrestrial crab
. It is the most terrestrial of the Caribbean
land crabs, and is found from western Cuba
across the Antilles
as far east as Barbados
. Common names for G. ruricola include the purple land crab, black land crab, red land crab, and zombie crab.
of G. ruricola grows in width at a rate of about 1 inches (2.5 cm) per year, with the crabs reaching maturity after 5 years, and living for up to 10 years in total. G. ruricola have a number of adaptation
s to terrestrial life, mostly regarding water conservation
. They are nocturnal, to prevent the hot sun from drying them out. They also have a "nephritic pad", onto which urine
is released, in order to be cleaned by microbes before the water is then reabsorbed.
, from Cuba
and the Bahamas in the west through the Antilles
to Barbados
in the east. It has been reported from Florida
and Nicaragua
, but few confirmed examples exist from the mainland; Loggerhead Key in the Dry Tortugas
marks the northenmost limit of its island distribution, which extends across the Bahamas and Cuba
, through the Greater Antilles
and Lesser Antilles
, to Barbados. Outlying populations exist on Curaçao
, in the Swan Islands
off Honduras
, and in the Archipelago of San Andrés, Providencia and Santa Catalina off the Colombia
n coast.
It can be found many kilometres from the sea, and at high altitude
s: crabs have been observed above 300 metres (984.3 ft) on the island of Dominica
, and at over 1000 metres (3,280.8 ft) on Jamaica
.
of G. ruricola hatch in the sea, where the larva
e live as plankton
. The return of the larvae to land seems to be infrequent, but when they do return, they return as megalopa larvae, in sufficient numbers to turn roads red. They move at a speed of 1–2 m/s (2.2–4.5 mph), or faster if startled. For the next three years, the young crabs live in burrow
s inhabited by other crabs and eat food brought back to the burrow by the older crab.
After mating, mass migrations
occur with the females returning to the sea to release their fertilised eggs. An average female carries around 85,000 eggs.
scavenger
, feeding mostly on nitrogen
-poor plant matter.
The meat of G. ruricola is rich in protein
, and has often been harvested by local people. Other predators may include bird
s, although information is scarce. When confronted, they rear up on and hold their open claws outwards in a defensive posture.
for two species of flies
in the genus Drosophila
. They were first observed on Montserrat
by Henry Guernsey Hubbard
in 1894, and presented at a scientific meeting later that year (where the crab was misidentified as Cardisoma guanhumi
), but no further research was conducted until 1955, when specimens were again collected, this time from Mona Island
, and named as Drosophila carcinophila by M. R. Wheeler.
In 1967, a second species of fly, Drosophila endobranchia
was discovered on Gecarcinus ruricola, although it also inhabits the closely related species Gecarcinus lateralis
. Drosohila endrobranchia is not closely related to D. carcinophila, and this trait appears therefore to have evolved convergently
. (A third species of fly, Lissocephala powelli has evolved a similar habit on Christmas Island
, where it lives on the land crabs Gecarcoidea lalandii
, Geograpsus crinipes and Cardisoma carnifex
, and the terrestrial hermit crab
Birgus latro.) D. endobranchia evolved from a group of species which breed on fungi or bark, while D. carcinophila evolved from a group which breed on cacti
.
The flies spend most of their lives on the crab, and are reluctant to leave. They do not need to flee predators, because the crabs they inhabit are fast animals and will flee:
The eggs
are laid around the crab's compound eyes, and the first instar
larva
e which hatch from the eggs migrate to the crab's nephritic pad, and live there, feeding on the microbes that cleanse the crab's urine. The second instar is spent in the crab's gill
chamber. The third instar sees the larvae return to the mouthparts before falling to the ground to pupate.
), noting the species' annual migrations from the forests to the coast (Habitat in America, sylvas vastissimis agminibus quotannis deserens littora maris petiturus: "lives in America; every year, an army marches out of the forests towards the sea").
n postage stamp
s for the International Year of the Ocean in 1998, under the name "mountain crab". These were a Tanzania
n stamp worth 500 shillingi
and a Uganda
n stamp worth 250 shillings
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of terrestrial crab
Land crab
Gecarcinidae is a family of true crabs that are adapted for terrestrial existence, commonly known as land crabs. Similar to all other crabs, land crabs possess a series of gills. In addition, the part of the carapace covering the gills is inflated and equipped with blood vessels. These organs...
. It is the most terrestrial of the Caribbean
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
land crabs, and is found from western Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
across the Antilles
Antilles
The Antilles islands form the greater part of the West Indies in the Caribbean Sea. The Antilles are divided into two major groups: the "Greater Antilles" to the north and west, including the larger islands of Cuba, Jamaica, Hispaniola , and Puerto Rico; and the smaller "Lesser Antilles" on the...
as far east as Barbados
Barbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
. Common names for G. ruricola include the purple land crab, black land crab, red land crab, and zombie crab.
Description
Four colour morphs exist within the species: black, red, yellow and green. The carapaceCarapace
A carapace is a dorsal 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 tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
of G. ruricola grows in width at a rate of about 1 inches (2.5 cm) per year, with the crabs reaching maturity after 5 years, and living for up to 10 years in total. G. ruricola have a number of adaptation
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
s to terrestrial life, mostly regarding water conservation
Water conservation
Water conservation refers to reducing the usage of water and recycling of waste water for different purposes such as cleaning, manufacturing, and agricultural irrigation.- Water conservation :Water conservation can be defined as:...
. They are nocturnal, to prevent the hot sun from drying them out. They also have a "nephritic pad", onto which urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
is released, in order to be cleaned by microbes before the water is then reabsorbed.
Distribution
G. ruricola is found across much of the CaribbeanCaribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
, from Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
and the Bahamas in the west through the Antilles
Antilles
The Antilles islands form the greater part of the West Indies in the Caribbean Sea. The Antilles are divided into two major groups: the "Greater Antilles" to the north and west, including the larger islands of Cuba, Jamaica, Hispaniola , and Puerto Rico; and the smaller "Lesser Antilles" on the...
to Barbados
Barbados
Barbados is an island country in the Lesser Antilles. It is in length and as much as in width, amounting to . It is situated in the western area of the North Atlantic and 100 kilometres east of the Windward Islands and the Caribbean Sea; therein, it is about east of the islands of Saint...
in the east. It has been reported from Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and Nicaragua
Nicaragua
Nicaragua is the largest country in the Central American American isthmus, bordered by Honduras to the north and Costa Rica to the south. The country is situated between 11 and 14 degrees north of the Equator in the Northern Hemisphere, which places it entirely within the tropics. The Pacific Ocean...
, but few confirmed examples exist from the mainland; Loggerhead Key in the Dry Tortugas
Dry Tortugas
The Dry Tortugas are a small group of islands, located at the end of the Florida Keys, USA, about west of Key West, and west of the Marquesas Keys, the closest islands. Still further west is the Tortugas Bank, which is completely submerged. The first Europeans to discover the islands were the...
marks the northenmost limit of its island distribution, which extends across the Bahamas and Cuba
Cuba
The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...
, through the Greater Antilles
Greater Antilles
The Greater Antilles are one of three island groups in the Caribbean. Comprising Cuba, Jamaica, Hispaniola , and Puerto Rico, the Greater Antilles constitute almost 90% of the land mass of the entire West Indies.-Greater Antilles in context :The islands of the Caribbean Sea, collectively known as...
and Lesser Antilles
Lesser Antilles
The Lesser Antilles are a long, partly volcanic island arc in the Western Hemisphere. Most of its islands form the eastern boundary of the Caribbean Sea with the Atlantic Ocean, with the remainder located in the southern Caribbean just north of South America...
, to Barbados. Outlying populations exist on Curaçao
Curaçao
Curaçao is an island in the southern Caribbean Sea, off the Venezuelan coast. The Country of Curaçao , which includes the main island plus the small, uninhabited island of Klein Curaçao , is a constituent country of the Kingdom of the Netherlands...
, in the Swan Islands
Swan Islands, Honduras
The Swan Islands, or Islas Santanilla, are a chain of three islands located in the northwestern Caribbean Sea, approximately ninety miles off the coastline of Honduras, with a land area of .-Detailed location and features:...
off Honduras
Honduras
Honduras is a republic in Central America. It was previously known as Spanish Honduras to differentiate it from British Honduras, which became the modern-day state of Belize...
, and in the Archipelago of San Andrés, Providencia and Santa Catalina off the Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
n coast.
It can be found many kilometres from the sea, and at high altitude
Altitude
Altitude or height is defined based on the context in which it is used . As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context...
s: crabs have been observed above 300 metres (984.3 ft) on the island of Dominica
Dominica
Dominica , officially the Commonwealth of Dominica, is an island nation in the Lesser Antilles region of the Caribbean Sea, south-southeast of Guadeloupe and northwest of Martinique. Its size is and the highest point in the country is Morne Diablotins, which has an elevation of . The Commonwealth...
, and at over 1000 metres (3,280.8 ft) on Jamaica
Jamaica
Jamaica is an island nation of the Greater Antilles, in length, up to in width and 10,990 square kilometres in area. It is situated in the Caribbean Sea, about south of Cuba, and west of Hispaniola, the island harbouring the nation-states Haiti and the Dominican Republic...
.
Life cycle
The eggsEgg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
of G. ruricola hatch in the sea, where the larva
Larva
A larva 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...
e live as plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
. The return of the larvae to land seems to be infrequent, but when they do return, they return as megalopa larvae, in sufficient numbers to turn roads red. They move at a speed of 1–2 m/s (2.2–4.5 mph), or faster if startled. For the next three years, the young crabs live in burrow
Burrow
A burrow is a hole or tunnel dug into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct of locomotion. Burrows provide a form of shelter against predation and exposure to the elements, so the burrowing way of life is quite popular among the...
s inhabited by other crabs and eat food brought back to the burrow by the older crab.
After mating, mass migrations
Animal migration
Animal migration is the relatively long-distance movement of individuals, usually on a seasonal basis. It is a ubiquitous phenomenon, found in all major animal groups, including birds, mammals, fish, reptiles, amphibians, insects, and crustaceans. The trigger for the migration may be local...
occur with the females returning to the sea to release their fertilised eggs. An average female carries around 85,000 eggs.
Ecology
G. ruricola is an omnivorousOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
scavenger
Scavenger
Scavenging is both a carnivorous and herbivorous feeding behavior in which individual scavengers search out dead animal and dead plant biomass on which to feed. The eating of carrion from the same species is referred to as cannibalism. Scavengers play an important role in the ecosystem by...
, feeding mostly on nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
-poor plant matter.
The meat of G. ruricola is rich in protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, and has often been harvested by local people. Other predators may include bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, although information is scarce. When confronted, they rear up on and hold their open claws outwards in a defensive posture.
Drosophila
G. ruricola is the host organismHost (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
for two species of flies
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
in the genus Drosophila
Drosophila
Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
. They were first observed on Montserrat
Montserrat
Montserrat is a British overseas territory located in the Leeward Islands, part of the chain of islands called the Lesser Antilles in the West Indies. This island measures approximately long and wide, giving of coastline...
by Henry Guernsey Hubbard
Henry Guernsey Hubbard
Henry Guernsey Hubbard was an American horticulturist, botanist, and entomologist.Henry Hubbard, first son of noted Michigan geologist, explorer and surveyor, Bela Hubbard, was born in Detroit, Michigan....
in 1894, and presented at a scientific meeting later that year (where the crab was misidentified as Cardisoma guanhumi
Cardisoma guanhumi
Cardisoma guanhumi, also known as the blue land crab, is a species of land crab found in tropical and subtopical estuaries and other maritime areas of land along the Atlantic coast of the Americas, from Brazil and Colombia, through the Caribbean, to the Bahamas, and as far north as Vero Beach,...
), but no further research was conducted until 1955, when specimens were again collected, this time from Mona Island
Mona, Puerto Rico
Mona is the third largest island of the archipelago of Puerto Rico, after the main island of Puerto Rico and Vieques. It is the largest of three islands located in the Mona Passage, a strait between the Dominican Republic and Puerto Rico, the others being Monito Island and Desecheo Island...
, and named as Drosophila carcinophila by M. R. Wheeler.
In 1967, a second species of fly, Drosophila endobranchia
Drosophila endobranchia
Drosophila endobranchia is a species of fly in the family Drosophilidae. The species, which is endemic to Grand Cayman, was discovered in 1966 and not found again until 2007, when it was rediscovered in the mouth region of a land crab.-Habitat:...
was discovered on Gecarcinus ruricola, although it also inhabits the closely related species Gecarcinus lateralis
Gecarcinus lateralis
Gecarcinus lateralis, also known by the common names blackback land crab, Bermuda land crab, red land crab and moon crab Gecarcinus lateralis, also known by the common names blackback land crab, Bermuda land crab, red land crab (leading to easy confusion with Gecarcoidea natalis) and moon crab...
. Drosohila endrobranchia is not closely related to D. carcinophila, and this trait appears therefore to have evolved convergently
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
. (A third species of fly, Lissocephala powelli has evolved a similar habit on Christmas Island
Christmas Island
The Territory of Christmas Island is a territory of Australia in the Indian Ocean. It is located northwest of the Western Australian city of Perth, south of the Indonesian capital, Jakarta, and ENE of the Cocos Islands....
, where it lives on the land crabs Gecarcoidea lalandii
Gecarcoidea lalandii
Gecarcoidea lalandii is a large species of terrestrial crab. It is dark purple in colour. It has long legs and short pincers. It is nocturnal, and spends most of the day hiding in burrows. Compared to the related G. natalis, G. lalandii is relatively widespread, being found in the Indo-Pacific...
, Geograpsus crinipes and Cardisoma carnifex
Cardisoma carnifex
Cardisoma carnifex is a species of terrestrial crab found in coastal regions from the east coast of Africa and the Red Sea across the Indo-Pacific to the Line Islands and the Tuamotu Archipelago. The range includes parts of northern Australia and the Cocos Islands....
, and the terrestrial hermit crab
Hermit crab
Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the 1100 species possess an asymmetrical abdomen which is concealed in an empty gastropod shell that is carried around by the hermit crab.-Description:...
Birgus latro.) D. endobranchia evolved from a group of species which breed on fungi or bark, while D. carcinophila evolved from a group which breed on cacti
Cactus
A cactus is a member of the plant family Cactaceae. Their distinctive appearance is a result of adaptations to conserve water in dry and/or hot environments. In most species, the stem has evolved to become photosynthetic and succulent, while the leaves have evolved into spines...
.
The flies spend most of their lives on the crab, and are reluctant to leave. They do not need to flee predators, because the crabs they inhabit are fast animals and will flee:
The flies … hardly move at all, are extremely reluctant in leaving their host crabs and are hard pushed to take flight. Although the flies are sluggish, the crabs on which they reside are anything but. Chasing after crabs through a pitch-black jungle (growing on a razor sharp labyrinthine limestone ground), while trying to aspirate flies from their carapaces is not trivial. Obtaining large amounts of flies in this way is simply a nightmare.
The eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
are laid around the crab's compound eyes, and the first instar
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
larva
Larva
A larva 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...
e which hatch from the eggs migrate to the crab's nephritic pad, and live there, feeding on the microbes that cleanse the crab's urine. The second instar is spent in the crab's gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...
chamber. The third instar sees the larvae return to the mouthparts before falling to the ground to pupate.
Linnaeus
Carl Linnaeus described the species in 1758 (the starting point for zoological nomenclatureInternational Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
), noting the species' annual migrations from the forests to the coast (Habitat in America, sylvas vastissimis agminibus quotannis deserens littora maris petiturus: "lives in America; every year, an army marches out of the forests towards the sea").
Philately
G. ruricola appeared on two AfricaAfrica
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n postage stamp
Postage stamp
A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...
s for the International Year of the Ocean in 1998, under the name "mountain crab". These were a Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
n stamp worth 500 shillingi
Tanzanian shilling
The shilingi is the currency of Tanzania, although widespread use of U.S. dollars is accepted. It is subdivided into 100 senti .The Tanzanian shilling replaced the East African shilling in 1966 at par....
and a Uganda
Uganda
Uganda , officially the Republic of Uganda, is a landlocked country in East Africa. Uganda is also known as the "Pearl of Africa". It is bordered on the east by Kenya, on the north by South Sudan, on the west by the Democratic Republic of the Congo, on the southwest by Rwanda, and on the south by...
n stamp worth 250 shillings
Ugandan shilling
The Shilling is the currency of Uganda. Technically, the shilling is subdivided into 100 cents but no subdivisions have been issued since the revaluation of the shilling in 1987.-History:...
.