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Cardisoma guanhumi is fundamental to the cuisine of many Caribbean nations as well as Florida and Venezuela; however, there is much concern regarding its excessive harvesting.
Cardisoma guanhumi communicates in various ways, but mainly with visual, auditory, and chemical signals. To attract mates, females release pheromones. To orient itself, C. guanhumi depends on polarized light or the light from the horizon at dawn or dusk. It also uses the setae on its appendages for tactile purposes. It is heavily sensitive to vibrations.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; polarized light ; tactile ; acoustic ; vibrations ; chemical
Although C. guanhumi is not endangered, there is concern regarding its harvesting. It has been exploited excessively in the Caribbean for food. To combat this, Puerto Rico enacted strict regulations and Florida is currently considering similar legislation.
US Federal List: no special status
CITES: no special status
Cardisoma guanhumi has a complex life cycle that begins during the rainy season (which varies by latitude) when females spawn their eggs into the ocean, strictly coinciding with the lunar cycle. Once hatched C. guanhumi molts through five larval periods before it undergoes metamorphosis into a megalops, the stage when the appendages first appear. The nest metamorphosis produces the juvenile crab, which closely resembles the adult form. Each metamorphosis is accompanied by a molting of the cuticle. The following molt, named the puberty molt, precedes full sexual maturation. Molting regulates the life cycle of C. guanhumi. Generally, C.guanhumi molts 60 times during its lifespan, compared to 20 times, which is typical of other crab species. After achieving sexual maturation, C. guanhumi becomes primarily terrestrial, returning to the ocean only to spawn and begin the life cycle once again.
Development - Life Cycle: metamorphosis
While the adverse affects on humans of C. guanhumi are minimal, it is sometimes deemed a garden pest for digging burrows in lawns and crop fields. In addition, it can occasionally cause ulcers and lesions to those who eat it when it has previously consumed poisonous fruit. Lastly, the pool at the bottom of the burrow provides a breeding ground for mosquitos that may potentially vector diseases such as malaria and subperiodic filariasis.
Negative Impacts: crop pest
Cardisoma guanhumi is a significant source of food in various parts of the Caribbean, particularly in Puerto Rico and the Bahamas. Harvesters have been known in Venezuela to catch as many as 400 giant land crabs per night. Sold at $30.00 (US) per dozen, this amounts to $1,000.00 per day per harvester in giant land crab revenues.
Positive Impacts: food
Due to the moist atmosphere within its burrow, C. guanhumi provides a myriad of arthropods with habitats. These arthropods live on its body, but do not seem to harm it, primarily feeding off of left over debris from previous C. guanhumi meals. Because the food habits of C. guanhumi are so eclectic, its effect on its prey populations are, if anything, trivial. However, through preferential feeding, C. guanhumi can alter the compositions of various species of plants by choosing to eat certain plants and seeds over others.
Ecosystem Impact: disperses seeds; creates habitat
Species Used as Host:
Mutualist Species:
Commensal/Parasitic Species:
Cardisoma guanhumi is an omnivore. Although it prefers leaves, fruits, and grasses, C. guanhumi also feeds on insects, carrion, and feces. To forage it typically does not stray far from its burrow and uses light and sound to find food. After foraging, it carries its food in its claws back to its burrow, eats, and saves whatever it does not finish for later.
Animal Foods: carrion ; insects; terrestrial non-insect arthropods
Plant Foods: leaves; fruit
Other Foods: detritus ; dung
Foraging Behavior: stores or caches food
Primary Diet: omnivore
Cardisoma guanhumi is found along the Gulf of Mexico and Caribbean Sea throughout the southeastern United States, Central America, the northern tip of South America, and parts of the Caribbean Islands.
Biogeographic Regions: nearctic ; neotropical ; atlantic ocean
Cardisoma guanhumi lives within several hundred meters of the shore, particularly along estuaries and river banks. It burrows in dense shrubbery, mud, or coastal sand above the tide line. Burrows can extend up to six feet underground, and contain small pools of water at the bottom. Cardisoma guanhumi shares its burrow with insects and other small arthropods. The atmospheres within such burrows typically have very high carbon dioxide concentrations because they are often sealed with mud.
Range elevation: N/A to N/A m.
Average elevation: Generally remains at sea level. m.
Range depth: N/A to N/A m.
Average depth: Generally remains at sea level. m.
Habitat Regions: terrestrial ; saltwater or marine
Terrestrial Biomes: forest ; rainforest
Aquatic Biomes: rivers and streams; temporary pools; coastal
Other Habitat Features: estuarine
Many giant land crabs do not survive the larval stage. Those who reach adulthood achieve sexual maturity in approximately four years. Unfortunately, there is not much further data available regarding the lifespan of C. guanhumi. However, biologists hypothesize that the lifespan of a species of land crab is inversely proportional to its growth rate. In other words, the faster they grow, the shorter they live, and vice versa. From this, it is probable that C. guanhumi has a relatively longer lifespan than other land crabs, as it grows more slowly and molts three times as much (averaging 60 molts per lifetime as opposed to 20). In fact, the largest female C. guanhumi kept in captivity lived 13 years. Albeit biologists admonish against extrapolating laboratory findings to a species' actual environment, I have given some rough estimates of lifespan below based on given data regarding the lifespans of C. guanhumi and other land crabs.
Range lifespan
Status: captivity: 13 (high) years.
Average lifespan
Status: wild: 11 years.
Average lifespan
Status: captivity: 11 years.
Cardisoma guanhumi grows roughly 127 mm wide and 102 mm long, weighing 400 g on average, though males are generally larger than females. As a juvenile, it is typically tan or brown in color with orange legs. As an adult, its coloring ranges from blue to violet, though some females are white or ashy gray. Its body, protected by a smooth carapace, consists of a cephalothorax and abdomen. Connected to its cephalothorax are five pairs of biramous appendages covered with tactile setae, each of which are sturdy and longer than the width of the cephalothorax. At its front are two pairs of antennae and two pincers, one larger than the other. The larger pincer in males can reach 300 mm in length. The difference in pincer size notwithstanding, C. guanhumi is bilaterally symmetric.
Average mass: 400 g.
Range length: 90 to 110 mm.
Average length: 102 mm.
Range wingspan: N/A to N/A mm.
Average wingspan: N/A mm.
Range basal metabolic rate: 330.307 micromole oxygen/hour to 388.171 micromole oxygen/hour. Note: could not find information expressed in cm3.O2/g/hr.
Average basal metabolic rate: 359.239 micromole oxygen/hour. Note: could not find information expressed in cm3.O2/g/hr.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; polymorphic
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
Due to their size, C. guanhumi is not heavily preyed on. However, it sometimes falls prey to large birds, mammals, and other C. guanhumi. Humans are the largest threat with respect to predation, harvesting giant land crabs in massive quantities for food. Fortunately, it is fairly safe in its burrow from predation. Hence, burrowing not only provides C. guanhumi with shelter, but also protects it from predation. In fact, the absence of a burrow, in addition to physical vulnerability and other factors, explains the high mortality rates of C. guanhumi during the larval stage.
Known Predators:
The reproductive cycle of C. guanhumi is heavily dependent on weather and the lunar cycle. At the beginning of the rainy season (typically late spring, but varies by latitude), females begin to actively search for a mate while migrating from their burrow to the shore. Major migrations take place prior to full moons; minor ones precede new moons. While males can copulate as much as they wish between molts, females can only copulate several times.
Mating System: polygynandrous (promiscuous)
Cardisoma guanhumi reaches sexual maturity at roughly four years of age. Mating begins during the rainy season when females migrate to the shore--particularly before a full moon and (to a far lesser extent) before a new moon. In preparation for their migrations, females gain substantial weight. Males actively court females and in response, females emit pheromones as well as tactile and auditory signals. Copulation typically takes place outside of burrows, and fertilization is internal. Following copulation, females carry their eggs (which can number anywhere between 20,000 and 1,200,000) for approximately two weeks before spawning them into the ocean.
Breeding interval: Cardisoma guanhumi breeds once a year.
Breeding season: Spring to late summer, though varies by latitude.
Range number of offspring: 20000 to 1200000.
Average number of offspring: 525000.
Average gestation period: 2 weeks.
Average time to independence: 2 weeks.
Average age at sexual or reproductive maturity (female): 4 years.
Average age at sexual or reproductive maturity (male): 4 years.
Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
After fertilization, females carry their eggs on their backs for approximately two weeks. At this point, the eggs begin to hatch, and she shakes them off into the ocean. In spite of its evolution toward terrestriality, C. guanhumi is still heavily dependent on the ocean for at least part of the life.
Parental Investment: pre-fertilization (Provisioning); pre-hatching/birth (Protecting: Female)
