The sharply contrasting black and white coloration, added to the stocky characteristic shape of a bear, makes the giant panda one of the most recognizable animals in the world. Pandas look a lot like other bears in terms of general shape and body structure. Because they chew tough bamboo stalks for nourishment, they have highly developed muscles around their jaw and large crushing molars. This makes their heads very round in appearance. When compared with other bears, the head of the giant panda is large in relation to its body. Panda forepaws are very flexible and have an enlarged wrist bone that acts as a unique 'sixth digit,' which works sort of like a human thumb. Pandas do not have heel pads on their hind feet like other bears, but they can still move around the dense forest silently and easily. The head, top of the neck and rump are white, while small patches of fur around the eyes, the ears, shoulders, front legs, and rear legs are black. In the wild their coloring can look more red or brown than black. Pandas have a short tail which is sometimes black. Their fur is thick with coarse outer hairs and dense wooly under-fur. The wrist bone, becoming extended to form an awkward, but functional, opposable thumb. The male genitalia are small and pointed to the rear, which is more similar to the red panda (Ailurus fulgens) than to other bears. Pandas also have an extremely thick esophagus so that they can swallow the large splinters of bamboo. Pandas are the most distinctively marked of all bears.