Blue land crab (Cardisoma guanhumi)

Right now at Tranquilo Bay we are having the reproductive migration of this curious animal. We have crabs all over the place, which is great, because this specie in some areas of the Caribbean has seen drastically reduced numbers . These crabs are intensively exploited as a food resource in some areas, however, in the areas where the animal it is not exploited as food the destruction of the habitat is the reason for the reduced population.

Photos by Natalia Decastro

Some data about them:

Young individuals are often very colourful, and as they grow older the colours tend to fade, females may be duller than males. This crab reaches sexual maturity in approximately 4 years, it is not uncommon for adult crabs to measure 10-11 cm and weigh up to 500 g.

This crab is a slow growing species compared to most other crabs, which makes it difficult for it to increase its population. While most crabs may require approximately 20 molts to reach maximum size, Cardisoma requires more than 60 molts.

One claw is usually considerably larger than the other. They feed throughout the day in shaded areas; however, if exposed to direct sunlight for prolonged periods, they prefer to feed at night. They are omnivores, but primarily feed on plant material, collected near the vicinity of its burrow.

The reproductive cycle is closely linked to seasonal weather patterns and lunar phase. Heavy rains in the spring initiate migrations. During this time they gain weight rapidly as foraging intensity is increased for the first few weeks of the migratory period. Males actively court ripe females during this period.

Fertilization is internal, and females carry external egg masses. Eggs are carried for approximately 2 weeks prior to hatching, and must be released into salt water for larvae to survive. The eggs hatch into free swimming larvae.