Cardisoma guanhumi
Encyclopedia
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, Florida
. The species varies in colour from dark blue to brown or pale grey, and may grow to 11 centimetres (4.3 in) in width and weigh over 500 grams (17.6 oz).
generally have a brown carpace with orange coloured legs. Females usually appear light gray or white. Adult colours are usually present between 80 g (2.8 oz) and 180 g (6.3 oz). The species can weigh over 500 g (17.6 oz).
and other coastal regions of the Caribbean, and along the Atlantic coast of Central and South America. In the United States it can be found in the Gulf of Mexico
and coastal areas of Florida, and as far north as Vero Beach
, Florida.
, collecting and eating leaves and fruits close to its burrow whilst also eating insects and carrion. Like many crabs, this species is cannibalistic
. If exposed to direct sunlight for prolonged periods, they prefer to feed at night.
are able to detect small vibrations on the ground within the range of 10–1500 Hz and 70 dB. Visual acuity
increases with body size due to an increase in both the number and diameter of ommatidia.
for the larvae to survive. Several spawns per year may occur with spawning season varying with location within the range. In Florida, spawning season lasts from June to December and reaches its peak in October and November. In the Bahamas the season extends from July to September, while in Venezuela
spawning lasts from July to November. Eggs hatch into free swimming larvae with 5 zoeal stages and 1 postlarval or megalopa stage. Typical development time from hatching to the first crabs stage is 42 days under laboratory conditions; however, this time may be much shorter in wild specimens.
C. guanhumi is a slow-growing species compared to most other crabs. It requires more than 60 molts – roughly three times more than other species of crab - to reach its full size. The crab will generally seal the exit to their burrow using mud, 6–10 days before they molt to protect themselves from predators. (After molting
they become more vulnerable to attack as their shell has not yet hardened.)
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...
found in tropical and subtopical estuaries and other maritime areas of land along the Atlantic coast
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
of the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...
, from Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
and 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...
, through 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....
, to the Bahamas, and as far north as Vero Beach, Florida
Vero Beach, Florida
Vero Beach is a city in Indian River County, Florida, USA. According to the U.S. Census Bureau's 2006 estimates, the city had a population of 16,939. It is the county seat of Indian River County...
. The species varies in colour from dark blue to brown or pale grey, and may grow to 11 centimetres (4.3 in) in width and weigh over 500 grams (17.6 oz).
Description
The carapace of C. guanhumi can reach sizes up to around 11 cm (4.3 in) and overall reaching sizes of up to 35 cm (13.8 in). Males, like many crabs possess dimorphic claws: the larger claw can grow up to around 15 cm (5.9 in) in length, (eventually becoming larger than the carpace itself). The eyes are stalked and its colour ranges from a deep blue to a pale grey, juvenilesJuvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
generally have a brown carpace with orange coloured legs. Females usually appear light gray or white. Adult colours are usually present between 80 g (2.8 oz) and 180 g (6.3 oz). The species can weigh over 500 g (17.6 oz).
Distribution
Cardisoma guanhumi is found throughout estuarineEstuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
and other coastal regions of the Caribbean, and along the Atlantic coast of Central and South America. In the United States it can be found in the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
and coastal areas of Florida, and as far north as Vero Beach
Vero Beach, Florida
Vero Beach is a city in Indian River County, Florida, USA. According to the U.S. Census Bureau's 2006 estimates, the city had a population of 16,939. It is the county seat of Indian River County...
, Florida.
Diet
Cardisoma guanhumi is omnivorousOmnivore
Omnivores are species that eat both plants and animals as their primary food source...
, collecting and eating leaves and fruits close to its burrow whilst also eating insects and carrion. Like many crabs, this species is cannibalistic
Cannibalism (zoology)
In zoology, cannibalism is the act of one individual of a species consuming all or part of another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded for more than 1500 species...
. If exposed to direct sunlight for prolonged periods, they prefer to feed at night.
Senses
Cardisoma guanhumi finds its food using light and sound detectors. Experiments show that crabs can be drawn out of their burrows to investigate the sound of falling fruit, once out they initiate a search for food. Predatory behavior is released in these crabs by detection of small moving objects. Crabs in the genus CardisomaCardisoma
Cardisoma is a genus of large land crabs. Three species formerly placed in this genus are now placed in Discoplax. The four species that remain in Cardisoma are found in warm coastal regions where they live in burrows...
are able to detect small vibrations on the ground within the range of 10–1500 Hz and 70 dB. Visual acuity
Visual acuity
Visual acuity is acuteness or clearness of vision, which is dependent on the sharpness of the retinal focus within the eye and the sensitivity of the interpretative faculty of the brain....
increases with body size due to an increase in both the number and diameter of ommatidia.
Life cycle
The reproductive cycle is closely linked to seasonal weather patterns and lunar phase. Heavy rains in the spring initiate migrations. When this occurs, C. guanhumi begins to gain weight, as more food is consumed and gathered for the first few weeks of the migratory period. Males mate with mature females during this time. Fertilization is internal, and throughout July and August most females carry the eggs externally. After approximately 2 weeks the eggs will hatch and must be released into saltwaterSeawater
Seawater is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% . This means that every kilogram of seawater has approximately of dissolved salts . The average density of seawater at the ocean surface is 1.025 g/ml...
for the larvae to survive. Several spawns per year may occur with spawning season varying with location within the range. In Florida, spawning season lasts from June to December and reaches its peak in October and November. In the Bahamas the season extends from July to September, while in Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
spawning lasts from July to November. Eggs hatch into free swimming larvae with 5 zoeal stages and 1 postlarval or megalopa stage. Typical development time from hatching to the first crabs stage is 42 days under laboratory conditions; however, this time may be much shorter in wild specimens.
C. guanhumi is a slow-growing species compared to most other crabs. It requires more than 60 molts – roughly three times more than other species of crab - to reach its full size. The crab will generally seal the exit to their burrow using mud, 6–10 days before they molt to protect themselves from predators. (After molting
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
they become more vulnerable to attack as their shell has not yet hardened.)