Both sexes of muskox have long, curved horns. Muskoxen stand 4 to 5 ft. high at the shoulder, with females measuring 4.4 to 6.6 ft. in length, and the larger males 6.6 to 8.2 ft. The small tail, often concealed under a layer of fur, measures only 3.9 inches long. Adults, on average, weigh 630 lbs. and range from 400 to 900 lbs. Their life expectancy is 12–20 years.