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Cardisoma guanhumi

Cardisoma guanhumi
Cardisoma guanhumi.jpg
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Infraorder: Brachyura
Family: Gecarcinidae
Genus: Cardisoma
Species: C. guanhumi
Binomial name
Cardisoma guanhumi
Latreille, 1825

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 and Gulf of Mexico, to the Bahamas, and north to 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 (18 oz).

The carapace of C. guanhumi can reach sizes up to around 11 cm (4.3 in) and individuals can reach sizes of up to 35 cm (14 in). As with many crab species, males possess dimorphic claws: the larger claw can grow up to around 15 cm (5.9 in) in length, eventually becoming larger than the carapace itself. The eyes are stalked and their colour ranges from a deep blue to a pale grey. Juveniles generally have a brown carapace 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). Individuals of the species can weigh over 500 g (18 oz).

Cardisoma guanhumi is found throughout estuarine and other coastal regions of the Caribbean, and along the Atlantic coast of Central and South America (south to Brazil). In the United States it can be found in coastal areas of the Gulf of Mexico and Florida north to Vero Beach.

Cardisoma guanhumi is omnivorous, collecting and eating leaves and fruits close to its burrow whilst also eating insects and carrion. Like many crabs, this species is cannibalistic. They move in the shade during the day and will eschew moving in prolonged direct sunlight to feed at night instead.

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 Cardisoma 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.


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