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
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 15
centimetres (6 in) in carapace width and weigh over 500 grams
A group of blue land crabs
5 Life cycle
7 External links
The carapace of C. guanhumi can reach a width up to 15 cm
(6 in). As with many crab species, males possess dimorphic
claws: the larger claw can grow up to around 15 cm (6 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
Gulf of Mexico and
Florida north to Vero
Beach. Relatively cold water temperatures in the winter, less than
20 °C (68 °F), affect the larval survival and restricts
the species' possibility of spreading further north.
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
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
Guarding the burrow
A juvenile blue land crab showing a different coloring
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.
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
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 its burrow using mud, 6–10 days before it molts, in
order to protect itself from predators. (After molting, crabs are more
vulnerable to attack as their shell has not yet hardened.)
^ a b Helmut Debelius (2001). Crustacea - Guide of the World (2nd
ed.). Frankfurt: IKAN Unterwasserarchiv.
^ a b c d e f g h i K. Hill (July 25, 2001). "
Smithsonian Marine Station at Fort Pierce.
^ a b M.E. Hostetler; F.J. Mazzotti; A.L. Taylor (December 2016).
Cardisoma guanhumi)". University of Florida,
Media related to
Cardisoma guanhumi at Wikimedia Commons
Data related to
Cardisoma guanhumi at Wikispecies
"Land crabs". StJohnBeachGuide.com. Archived from the original on July
1, 2007. Retrieved June 19, 2007.