Anyone finding a crab that looks like it is wearing mittens should notify the Smithsonian where researchers are tracking the spread of the Chinese mitten crab, named for their furry claws. The crabs pose a threat because they burrow into mud and other areas and can damage stream banks, dams, levees and water intake pipes. They were first spotted in the Chesapeake in 2006, and researchers want to know what impact they are having on native crabs and the environment. The Smithsonian says if you find a mitten crab, do not throw it back into the water. Freeze it or put it on ice, take a photo, note where it was found and then contact the Smithsonian.