Friday, July 8, 2011

Cardisoma guanhumi

Today, I ran into what seemed to be a large army of these blue side crawling creatures. They look quite formidable and always ready to pick a fight. Literally, after so many rainy days, areas near water can face a large invasion of these blue invaders. Here they come, the blue land crabs (Cardisoma guanhumi) which is a large burrowing crab whose distribution on land is generally limited to within 5 km of the ocean. Large individuals may grow to over 11 cm and weigh over 500 grams.

Cardisoma guanhumi is a circumequatorial species found throughout estuarine regions of the Caribbean, Central and South America including Columbia, Venezuela, the Bahamas, and Puerto Rico. Within the U.S. it is limited to the Gulf of Mexico and coastal Florida and is rarely found more than 8 km from the ocean. It is found in greatest concentration on low lying ground, and burrow concentrations in these optimum habitat areas may exceed 7500 per acre. In Central and South America, as well as in the Bahamas, Cardisoma guanhumi is eaten as food. However, in the U.S. and in much of Puerto Rico it is considered a pest. I can tell you, having seen hundreds of them scurrying around here today, that I am quite afraid of them. Pests they are, in my humble opinion!

The population distribution of this species is heavily influenced by water temperature. In areas where water temperatures fall below 20 C in winter, larval survival is affected. Within the U.S., Cardisoma guanhumi has been observed as far north as Vero Beach, Florida. However, north of this area, water temperatures in the winter limit the growth of large populations of them.

In any case, they don't look very appetizing to me so I'll pass! This guy is caught off guard away from his hole so he is trying to fight his way back to his den.
Blue Land Crab

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