Blue land crab

Appearance

The carapace of "C. guanhumi" can reach sizes up to around 11 cm and individuals can reach sizes of up to 35 cm. As with many crab species, males possess dimorphic claws: the larger claw can grow up to around 15 cm 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 and 180 g. Individuals of the species can weigh over 500 g.

Distribution

"Cardisoma guanhumi" is found throughout estuarine 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 Ormond Beach, Florida.

Behavior

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 saltwater 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.

Food

"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.