Panopeus herbstii is the largest mud crab to be found in the Chesapeake Bay—nevertheless, it rarely exceeds two inches in size. Its range extends along the East Coast from Cape Cod to Florida. This arthropod is a benthic predator and scavenger which usually feeds on young bivalves such as oysters and clams and other shellfish such as periwinkles, and is fed upon by a wide diversity of larger aquatic animals.
The black-fingered mud crab’s powerful, compact exoskeleton and strong claws effectively crush the shells of mollusks close to its own size, and it can chip away at the tough calcereous shells of barnacles. This species is especially fond of consuming hermit crabs, which it accomplishes first by seizing the hermit’s protruding legs and then pulling the animal from its shell.
The black-fingered mud crab is so-called for its powerful, black-tipped claws of unequal size. The claw’s undersides are pale in color.
The mud crab’s shell is wider than it is long, and has five ‘teeth’.
This species of mud crab is shy and prefers to live and breed among sponge colonies, under rocks and debris along shorelines and among dense thickets of aquatic vegetation.
The mud crab often lives—though is not often glimpsed—in shallow-water habitats with muddy substrates, and will also live among the detritus of other species, sometimes in abandoned oyster shells.
The mud crab also may create burrows under other shells and stones.
Other tiny species of fish, such as gobies, sometimes enter into a symbiosis with mud crabs. For example, they may share the oyster shells that the mud crab has cleaned. The gobie is thus sheltered from larger fish, and the mud crab, whose eyesight is poor, is protected from its many predators by the gobie’s sharper vision. When the gobie swims suddenly to safety, the mud crab follows.
For more information, contact the Chesapeake
Bay Program Office:
410 Severn Avenue, Suite 109, Annapolis, MD 21403 / Tel: (800)
YOUR-BAY / Fax: (410) 267-5777.
