June 7, 2016
The National Environment and Planning Agency (NEPA) is advising the public that there is no reason for alarm regarding the recent sighting of hundreds of black land crabs along the St. Thomas shoreline as the occurrence is a normal part of the animal’s life cycle.
The Black Land Crabs spend their adult life in the terrestrial environment, but are still dependent on the ocean for at least part of their life cycle.
According to the Agency, similar events were witnessed by residents in Nine Miles and Bull Bay, St. Thomas a decade ago. During the events, hundreds of juvenile crustaceans traversed the beach from the sea to the adjoining mangrove forest.
The Agency says what is now occurring is the adult females are traversing the beach en-route to the sea as part of their life cycle.
NEPA is reiterating that the event is a natural occurrence and is vital to the survival of the species. Ecologically the black land crab plays a role in soil dynamics and nutrient cycling in the environment.
The public is therefore encouraged not to harvest the egg-laden adults as this will negatively impact the population of the species.
More on the Black Land Crab’s Reproductive Biology: Following mating, the female crab migrates to the sea and to lay her eggs. During the peak of the spawning period the land crab moves to the sea along a migratory route causing it to appear as a mass migration to the sea via roadways, gullies, beaches and mangrove areas. Near the sea they lay their eggs, incubate them for approximately two weeks, and then enter the sea briefly for the larvae to hatch. The larvae released into the sea must drift and develop for about 20 days and if the currents have been favourable, those that are lucky to survive come back to shore to migrate inland to continue their life cycle.
Please see additional information below by Jamaican Scientist, Dr Karl Aiken about the mass emergence of juvenile land crabs in St Thomas in 2006.