Fox vibrissae, or whiskers, are black. Many small therocephalians have small pits on their snouts that probably supported vibrissae or whiskers. Its vibrissae (whiskers) are long and thick, enhancing sensory perception underwater and on land. Many species have long, sensitive whiskers or vibrissae for touch or "whisking". Fur seals are characterized by their external pinnae, dense underfur, vibrissae, and long, muscular limbs. Its facial vibrissae (whiskers) are long, with the longest being longer than its head. Manatees have sensitive tactile hairs that cover their bodies and faces called vibrissae. The postvertical orbital bristles are absent, as are the vibrissae. Facial vibrissae on the maned sloth are sparse. By holding their vibrissae steady, pinnipeds are able to maximize their detection ability. The follicles of some groups of vibrissae in some species are motile. The vibrissae of phocids are undulated and wavy while otariid and walrus vibrissae are smooth. Apart from cranial vibrissae, other groups are found elsewhere on the body. Aside from the vibrissae, the walrus is sparsely covered with fur and appears bald.