Male okapis have short, distinct horn-like protuberances on their heads called ossicones, less than 15 cm (5.9 in) in length.

[3] Okapis are herbivores, feeding on tree leaves and buds, grasses, ferns, fruits, and fungi.

[6][7] The animal was brought to prominent European attention by speculation on its existence found in press reports covering Henry Morton Stanley's journeys in 1887.

In his travelogue of exploring the Congo, Stanley mentioned a kind of donkey that the natives called the atti, which scholars later identified as the okapi.

[8] When the British special commissioner in Uganda, Sir Harry Johnston, discovered some Pygmy inhabitants of the Congo being abducted by a showman for exhibition, he rescued them and promised to return them to their homes.

From this skull, the okapi was correctly classified as a relative of the giraffe; in 1901, the species was formally recognized as Okapia johnstoni.

[10][13] In 1901, Sclater presented a painting of the okapi before the Zoological Society of London that depicted its physical features with some clarity.

[14] Based on the description of the okapi by Pygmies, who referred to it as a "horse", Sclater named the species Equus johnstoni.

[16] In 1902, Swiss zoologist Charles Immanuel Forsyth Major suggested the inclusion of O. johnstoni in the extinct giraffid subfamily Palaeotraginae.

However, the species was placed in its own subfamily Okapiinae, by Swedish palaeontologist Birger Bohlin in 1926,[17] mainly due to the lack of a cingulum, a major feature of the palaeotragids.

[19] The earliest members of the Giraffidae first appeared in the early Miocene in Africa, having diverged from the superficially deer-like climacoceratids.

[20] Several important primitive giraffids existed more or less contemporaneously in the Miocene (23–10 million years ago), including Canthumeryx, Giraffokeryx, Palaeotragus, and Samotherium.

[22] The okapi is sometimes referred to as a living fossil, as it has existed as a species over a long geological time period, and morphologically resembles more primitive forms (e.g.

[16][23] In 2016, a genetic study found that the common ancestor of giraffe and okapi lived about 11.5 million years ago.

[28] The okapi exhibits sexual dimorphism, with females 4.2 cm (1.7 in) taller on average, slightly redder, and lacking prominent ossicones, instead possessing hair whorls.

The large number of rod cells in the retina facilitate night vision, and an efficient olfactory system is present.

Morphological features shared between the giraffe and the okapi include a similar gait – both use a pacing gait, stepping simultaneously with the front and the hind leg on the same side of the body, unlike other ungulates that walk by moving alternate legs on either side of the body[32] – and a long, black tongue (longer in the okapi) useful for plucking buds and leaves, as well as for grooming.

Individuals may engage in Flehmen response, a visual expression in which the animal curls back its upper lips, displays the teeth, and inhales through the mouth for a few seconds.

[27] Okapis are herbivores, feeding on tree leaves and buds, branches, grasses, ferns, fruits, and fungi.

[35] They are unique in the Ituri Forest as they are the only known mammal that feeds solely on understory vegetation, where they use their 18-inch-long (46 cm) tongues to selectively browse for suitable plants.

The main constituents of the diet are woody, dicotyledonous species; monocotyledonous plants are not eaten regularly.

In the Ituri forest, the okapi feeds mainly upon the plant families Acanthaceae, Ebenaceae, Euphorbiaceae, Flacourtiaceae, Loganiaceae, Rubiaceae, and Violaceae.

The male shows his interest by extending his neck, tossing his head, and protruding one leg forward.

[29] The gestational period is around 440 to 450 days long, following which usually a single calf is born, weighing 14–30 kg (31–66 lb).

The udder of the pregnant female starts swelling 2 months before parturition, and vulval discharges may occur.

Results of research conducted in the late 1980s in a mixed Cynometra forest indicated that the okapi population density averaged 0.53 animals per square kilometre.

A threat that has emerged quite recently is the presence of illegal armed groups around protected areas, inhibiting conservation and monitoring actions.

A small population occurs north of the Virunga National Park, but lacks protection due to the presence of armed groups in the vicinity.

[1] In November 2011, the White Oak Conservation center and Jacksonville Zoo and Gardens hosted an international meeting of the Okapi Species Survival Plan and the Okapi European Endangered Species Programme at Jacksonville, which was attended by representatives from zoos from the US, Europe, and Japan.

The okapi population is managed in America by the AZA's Species Survival Plan, a breeding program that works to ensure genetic diversity in the captive population of endangered animals, while the EEP (European studbook) and ISB (Global studbook) are managed by Antwerp Zoo in Belgium, which was the first zoo to have an Okapi on display (in 1919), as well as one of the most successful in breeding them.