The addax (Addax nasomaculatus) is an antelope native to the Sahara Desert. The only member of the genus Addax, it was first described scientifically by Henri de Blainville in 1816. Addax are well-adapted to exist in their desert habitat, as they can live without water for long periods of time. Although extremely rare in their native habitat due to unregulated hunting, addax are quite common in captivity. They were once abundant in North Africa but currently are only native to a few countries. They are extirpated from Algeria, Egypt, Libya, Sudan, and Western Sahara, but have been reintroduced into Morocco and Tunisia.
The addax is a spiral-horned antelope. The horns, which are found on both males and females, have two to three twists and are typically 55-80 cm (22-31 in) in females and 70-85 cm (28-33 in) in males, although the maximum recorded length is 109.2 cm (43.0 in). The lower and middle portions of the horns are marked with a series of 30 to 35 ring-shaped ridges. The coloring of the addax's coat varies with the season. In the winter, it is greyish-brown with white hindquarters and legs, and long, brown hair on the head, neck, and shoulders. In the summer, the coat turns almost completely white or sandy blonde. Their head is marked with brown or black patches that form an 'X' over their noses. They have scraggly beards and prominent red nostrils. Long, black hairs stick out between their curved and spiraling horns, ending in a short mane on the neck. The tail is short and slender, ending in a puff of black hair. The hooves are broad with flat soles and strong dewclaws to help them walk on soft sand. All four feet possess scent glands. The females of this species are smaller than the males.