SCDNR: Snap photos of non-native blue land crabs

CHARLESTON COUNTY, S.C. (WCBD) – People living along the South Carolina coast are encouraged to report sightings of a non-native blue land crab.

The South Carolina Department of Natural Resources (SCDNR) on Friday said those living near the coast who encounter what looks like an enormous fiddler crab should snap a photo and report it to the agency.

Biologists said the reports will help them learn more about where the non-native species are spreading. It comes after SCDNR received numerous reports of people spotting the blue land crab, or Cardisoma guanhumi.

According to SCDNR, the blue land crab is native along the Atlantic Coast from Brazil to south Florida – but occasional sightings of the large crabs have been reported in South Carolina since 2018.

“Researchers do not yet know the extent of the crab’s distribution in South Carolina nor its impact on the environment and other wildlife,” said SCDNR. “Whether the species arrived through natural expansion of its range or human-mediated sources is also not clear.”

Biologists said blue land crabs can reach up to six inches wide across the shell, making them comparable in size to native blue swimming crabs.  “Unlike our native blue crabs, they’re terrestrial, typically digging deep burrows within a few miles of coastal waterways,” SCDNR said.

The burrows can extend up to six feet deep in search of water, which can damage yards, gardens, and crop fields — it’s one of the reasons the crabs are considered pests. The crabs have a preference to feed on fruit and vegetation.

The crabs come in a variety of colors – adult males may have a blue-gray coloring while females can either be white or ash-gray and juveniles can vary from orangish to dark brown to purple. They also have an unusually long life span and grow slower compared to other crabs, being considered mature at four years old and living up to eleven years, officials said.

“Males can be differentiated from females by the shape of the ‘apron’ on their undersides,” SCDNR said. “Males have a thin, pointy apron, while females have a wide, domed apron.”

While blue land crabs are eaten, they are difficult to catch.

Biologists are asking coastal state residents to take a picture and report any blue land crabs sightings. Officials say the recent heavy rain along South Carolina’s coastline can drive the crabs out of their burrows making them easier to spot.