Is this non-native crab burrowed in your backyard? SCDNR wants to hear about it
No one is quite sure how palm-sized crabs that burrow deep into the Earth and sport shells that range from pale orange to blue-gray made it to South Carolina.
The non-native blue land crab could’ve hitched a ride in fresh or saltwater held in the ballast tanks on boats and ships. That water provides stability to the vessel, but when the craft arrives at its stop and releases the ballast water, it can free non-native species.
Another option is blue land crabs, along with other Florida species, are experiencing natural range expansion as waters and temperatures warm due to climate change, South Carolina Department of Natural Resources’ Erin Weeks said.
Either way, SCDNR is just getting started scoping out the blue land crab, which is native along the Atlantic coast from Brazil to South Florida.
In the past month, about half a dozen sightings have been reported to the agency. While the number is small, it’s about the same amount the state’s seen in the last decade. Researchers believe recent sightings have coincided with heavy rains that have swamped the crabs out of their burrows.
Along with unanswered question of how the terrestrial arthropods got here, biologists aren’t sure what kind of impact the crab may have on South Carolina’s other crab species, crustaceans and the environments they inhabit.
“The first step for us in the fact-finding mission is to figure out — how widespread is this species? Where is it showing up? How far inland are people seeing it?” Weeks said.
Knowing the answers to these questions will lead to the deeper work. For now, the state’s Department of Natural Resources is asking people to snap photos of the blue land crab and report sightings of it online.
Or, reach Weeks at WeeksE@dnr.sc.gov.
To the untrained eye, one could say the blue land crab, not native to the Palmetto State, looks like a gigantic fiddler crab. Others may compare the species to the native blue swimming crabs. But these non-native arthropods, long-living and slow-growing, can reach up to 6 inches wide across its shell, according to SCDNR.
Males usually have a predictable blue-gray coloring, but the females can be white or ash-gray. Juvenile blue land crabs can span from a ruddy orange to brown to purple. On the underside of the crab, males’ “aprons” are thin and pointed, while the females’ apron is wide and domed.
Regardless of shade and shape, blue land crabs can be found tunneled up to 6 feet underground and as far as 5 miles inland from a water source.
“We’re talking suburban Mount Pleasant,” Weeks said.
Here’s the catch: Blue land crabs can end up burrowing in your yard in a way that Weeks noted to be “quite dramatic.”
In the process, they can damage yards, crop field, gardens, and they love to snack on fruit and vegetation. However, the speedy movers aren’t exactly easy to catch. If you manage to track one down and get a photo, SCDNR wants to know.
“Just keep an eye out and let us know if you see something that you think looks off,” Weeks said, reminding that it is, in fact, illegal to release non native species in South Carolina.
This story was originally published September 2, 2022 at 2:28 PM with the headline "Is this non-native crab burrowed in your backyard? SCDNR wants to hear about it."
