Black-fingered Mud Crab

Panopeus herbstii

The black-fingered mud crab is a tiny, grayish-brown crab with powerful, black-tipped claws, one bigger than the other.

• The larger claw, called the major claw, has a large tooth on the movable "finger" of the claw.
• The mud crab's carapace, or shell, is wider than it is long, with five "teeth."

Black-fingered mud crabs grow to about 1.5 inches wide.

Where does the black-fingered mud crab live?

Black-fingered mud crabs are found on and around rocks, mud flats, pilings, oyster reefs, grass beds and sponge colonies near the shore. They sometimes create burrows under shells and stones. Black-fingered mud crabs range from the salty mouth of the Bay up to moderately brackish waters.

What does the black-fingered mud crab eat?

Black-fingered mud crabs use their strong claws to crush the shells of young clams and oysters, barnacles, periwinkles and other shellfish. They will also feed on hermit crabs by seizing a hermit crab's protruding legs and pulling it from its shell.

How does the black-fingered mud crab reproduce?

Black-fingered mud crabs spawn during the summer months. Larvae development includes:

• Four zoea stages, during which the free-swimming larvae have primitive legs and a spiny carapace.
• One megalops stage.

Other facts about the black-fingered mud crab:

• Even though it is a tiny crab, the black-fingered mud crab is the largest mud crab found in the Bay.
• Mud crabs are major predators of juvenile oysters in the Bay.