Blue Land Crab

The carapace of Cardisoma guanhumi can reach a width up to 15 centimetres (6 inches). As with many crab species, males possess dimorphic claws; the larger claw can become longer than the carapace's width. 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 grams (2.8 ounces) and 180 g (6.3 oz). Individuals of the species can weigh over 500 g (18 oz).

C. 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. Relatively cold water in the winter, less than 20 °C (68 °F), affects larval survival and restricts the species' possibility of spreading further north.

C. 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.