The black fingered mud crab is the largest mud crab. Its scientific name is Panopeus herbstii. It is classified as a true crab, belonging to the infraorder Brachyura.

The black fingered mud crab is small, growing up to be about 4cm. It has black tipped claws of an unequal size. The black fingered mud crab has a strong exoskeleton, with very thick and strong claws. The shell is a dull gray and brown color.

The black fingered mud crab is found on muddy bottoms where it takes refuge under stones and shells or among sponges and weeds. But, they are rarely seen in the open.

The black fingered mud crab has a small diet, feeding on mainly young clams, oysters, and periwinkles. It cracks open their shells with its strong claws. Mud crabs are especially fond of hermit crabs, which are grasped by the legs and pulled out of its protective shell. Like most mud crabs it is a scavenger. Young black fingered mud crabs are an important food source to other marine animals.