Okapi

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This article is about the animal. For other uses, see Okapi (disambiguation).

Okapi
Male okapi at Beauval Zoo
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Giraffidae
Genus: Okapia
Lankester, 1901
Species:
O. johnstoni
Binomial name
Okapia johnstoni
(
P.L. Sclater
, 1901)
Range of the okapi

The okapi (

endemic to the northeast Democratic Republic of the Congo in central Africa. However, non-invasive genetic identification has suggested that a population has occurred south-west of the Congo River as well.[2] It is the only species in the genus Okapia. Although the okapi has striped markings reminiscent of zebras, it is most closely related to the giraffe. The okapi and the giraffe are the only living members of the family Giraffidae
.

The okapi stands about 1.5 m (4 ft 11 in) tall at the shoulder and has a typical body length around 2.5 m (8 ft 2 in). Its weight ranges from 200 to 350 kg (440 to 770 lb). It has a long neck, and large, flexible ears. Its coat is a chocolate to reddish brown, much in contrast with the white horizontal stripes and rings on the legs, and white ankles. Male okapis have short, distinct horn-like protuberances on their heads called ossicones, less than 15 cm (5.9 in) in length. Females possess hair whorls, and ossicones are absent.

Okapis are primarily

gestational period
is around 440 to 450 days long, following which usually a single calf is born. The juveniles are kept in hiding, and nursing takes place infrequently. Juveniles start taking solid food from three months, and weaning takes place at six months.

Okapis inhabit

endangered. Major threats include habitat loss due to logging and human settlement. Illegal mining and extensive hunting for bushmeat and skin have also led to a decline in populations. The Okapi Conservation Project
was established in 1987 to protect okapi populations.

Etymology and taxonomy

Strips cut from the striped part of the skin of an okapi, sent home by Sir Harry Johnston, were the first evidence of the okapi's existence to reach Europe.

Although the okapi was unknown to the Western world until the 20th century, it may have been depicted since the early fifth century BCE on the

Achaemenid kingdom.[3][4]

For years, Europeans in Africa had heard of an animal that they came to call the African unicorn.[5][6] 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.[citation needed]

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. The Pygmies fed Johnston's curiosity about the animal mentioned in Stanley's book. Johnston was puzzled by the okapi tracks the natives showed him; while he had expected to be on the trail of some sort of forest-dwelling horse, the tracks were of a cloven-hoofed beast.[7]

Illustration from an original painting by Sir Harry Johnston, based on preserved skins (1901)

Though Johnston did not see an okapi himself, he did manage to obtain pieces of striped skin and eventually a skull. From this skull, the okapi was correctly classified as a relative of the giraffe; in 1901, the species was formally recognized as Okapia johnstoni.[8]

Okapia johnstoni was first described as Equus johnstoni by English zoologist

Ituri Forest.[8][11]

In 1901, Sclater presented a painting of the okapi before the Zoological Society of London that depicted its physical features with some clarity. Much confusion arose regarding the taxonomical status of this newly discovered animal. Sir Harry Johnston himself called it a Helladotherium, or a relative of other extinct giraffids.[12] Based on the description of the okapi by Pygmies, who referred to it as a "horse", Sclater named the species Equus johnstoni.[13] Subsequently, zoologist Ray Lankester declared that the okapi represented an unknown genus of the Giraffidae, which he placed in its own genus, Okapia, and assigned the name Okapia johnstoni to the species.[14]

In 1902, Swiss zoologist

Giraffa on the basis of cladistic analysis. The two genera together with Palaeotragus constitute the tribe Giraffini.[17]

Evolution

Despite the vast difference in neck length, the okapi (left) and the giraffe (right) both have seven cervical vertebrae (as do all mammals except for manatees and sloths).

The earliest members of the Giraffidae first appeared in the early

radiation. Another radiation began in the Pliocene, but was terminated by a decline in diversity in the Pleistocene.[18] Several important primitive giraffids existed more or less contemporaneously in the Miocene (23–10 million years ago), including Canthumeryx, Giraffokeryx, Palaeotragus, and Samotherium. According to palaeontologist and author Kathleen Hunt, Samotherium split into Okapia (18 million years ago) and Giraffa (12 million years ago).[19] However, J. D. Skinner argued that Canthumeryx gave rise to the okapi and giraffe through the latter three genera and that the okapi is the extant form of Palaeotragus.[20] 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. Samotherium).[14][21]

In 2016, a genetic study found that the common ancestor of giraffe and okapi lived about 11.5 million years ago.[22]

Description

Male okapi displaying his striking horizontal stripes

The okapi is a medium-sized giraffid, standing 1.5 m (4 ft 11 in) tall at the shoulder. Its average body length is about 2.5 m (8 ft 2 in) and its weight ranges from 200 to 350 kg (440 to 770 lb).

Interdigital glands are present on all four feet, and are slightly larger on the front feet.[25] Male okapis have short, hair-covered horn-like structures called ossicones, less than 15 cm (5.9 in) in length, which are similar in form and function to the ossicones of a giraffe.[26] 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.[27][28]

The okapi shows several adaptations to its tropical habitat. The large number of

crowned and finely cusped, and efficiently cut tender foliage. The large cecum and colon help in microbial digestion, and a quick rate of food passage allows for lower cell wall digestion than in other ruminants.[29]

Head of a male okapi with damaged ossicones

The okapi is easily distinguished from its nearest extant relative, the giraffe. It is much smaller than the giraffe and shares more external similarities with

cervids. Ossicones are present only in the male okapi, while both sexes of giraffe possess this feature. The okapi has large palatine sinuses (hollow cavities in the palate), unique among the giraffids. 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[30] – and a long, black tongue (longer in the okapi) useful for plucking buds and leaves, as well as for grooming.[29]

Ecology and behaviour

Okapis are primarily

diurnal, but may be active for a few hours in darkness.[31] They are essentially solitary, coming together only to breed. They have overlapping home ranges and typically occur at densities around 0.6 animals per square kilometre.[24] Male home ranges average 13 km2 (5.0 sq mi), while female home ranges average 3–5 km2 (1.2–1.9 sq mi). Males migrate continuously, while females are sedentary.[32] Males often mark territories and bushes with their urine, while females use common defecation sites. Grooming is a common practice, focused at the earlobes and the neck. Okapis often rub their necks against trees, leaving a brown exudate.[25]

The male is protective of his territory, but allows females to pass through the domain to forage. Males visit female home ranges at breeding time.

vocal cords are poorly developed, vocal communication is mainly restricted to three sounds — "chuff" (contact calls used by both sexes), "moan" (by females during courtship) and "bleat" (by infants under stress). 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. The leopard is the main natural predator of the okapi.[25]

Diet

The long tongue of the okapi

Okapis are

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.[25][32]

Reproduction

A female okapi with her calf at White Oak Conservation

Female okapis become sexually mature at about one-and-a-half years old, while males reach maturity after two years.

estrus in females does not depend on the season. In captivity, estrous cycles recur every 15 days.[29][35] The male and the female begin courtship by circling, smelling, and licking each other. The male shows his interest by extending his neck, tossing his head, and protruding one leg forward. This is followed by mounting and copulation.[27]

The

parturition, and vulval discharges may occur. Parturition takes 3–4 hours, and the female stands throughout this period, though she may rest during brief intervals. The mother consumes the afterbirth and extensively grooms the infant. Her milk is very rich in proteins and low in fat.[29]

As in other ruminants, the infant can stand within 30 minutes of birth. Although generally similar to adults, newborn calves have long hairs around the eye (resembling false eyelashes), a long dorsal mane, and long white hairs in the stripes.[36] These features gradually disappear and give way to the general appearance within a year. The juveniles are kept in hiding, and nursing takes place infrequently. Calves are known not to defecate for the first month or two of life, which is hypothesized to help avoid predator detection in their most vulnerable phase of life.[37] The growth rate of calves is appreciably high in the first few months of life, after which it gradually declines. Juveniles start taking solid food from 3 months, and weaning takes place at 6 months. Ossicone development in males takes 1 year after birth. The okapi's typical lifespan is 20–30 years.[25]

Distribution and habitat

The okapi is

Ituri rainforest, then through the river basins of the Rubi, Lake Tele, and Ebola to the west and the Ubangi River further north. Smaller populations exist west and south of the Congo River. It is also common in the Wamba and Epulu areas. It is extinct in Uganda.[1]

The okapi inhabits

inselbergs that offer forage uncommon elsewhere. 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.[32] In 2008, it was recorded in Virunga National Park.[38] There is also evidence that okapis were also observed in the Semuliki Valley in Uganda by Europeans, but later became extinct in the late 1970s.[39] The Semuliki Valley provides a similar habitat to the Congo Basin
.

Status

Threats and conservation

Okapi at Disney's Animal Kingdom

The IUCN classifies the okapi as endangered.

Rubi Tele Hunting Reserve and the Abumombanzi Reserve. Major threats include habitat loss due to logging and human settlement. Extensive hunting for bushmeat and skin and illegal mining have also led to population declines. 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 June 2012, a gang of poachers attacked the headquarters of the Okapi Wildlife Reserve, killing six guards and other staff[41] as well as all 14 okapis at their breeding center.[42]

The

Jacksonville, which was attended by representatives from zoos from the US, Europe, and Japan. The aim was to discuss the management of captive okapis and arrange support for okapi conservation. Many zoos in North America and Europe currently have okapis in captivity.[43]

Okapis in zoos

1960 Dutch newsreel about okapis in Diergaarde Blijdorp

Around 100 okapis are in accredited

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.[44][45]

In 1937, the

Brookfield Zoo in Chicago has also greatly contributed to the captive population of okapis in accredited zoos. The zoo has had 28 okapi births since 1959.[50]

Other North American zoos that exhibit and breed okapis include:

Henry Doorly Zoo and Aquarium (Nebraska); Philadelphia Zoo (Pennsylvania); Potawatomi Zoo[52] (Indiana); Oklahoma City Zoo and Botanical Garden (Oklahoma); and Blank Park Zoo (Iowa).[53]

In Europe, zoos that exhibit and breed okapis include:

Dvůr Králové Zoo (Czech Republic); Wrocław Zoo (Poland); Bioparc Zoo de Doué and ZooParc de Beauval (France); and Lisbon Zoo (Portugal).[56]

In Asia, three Japanese zoos exhibit okapis: Ueno Zoo in Tokyo; Kanazawa Zoo and Zoorasia in Yokohama.[57]

See also

References

  1. ^
    doi:10.2305/IUCN.UK.2015-4.RLTS.T15188A51140517.en
    . Retrieved 19 November 2021.
  2. doi:10.1017/S0030605314000593
    .
  3. ^ The Oriental Institute of the University of Chicago, Photographic Archives Archived 8 July 2008 at the Wayback Machine; photo detail Archived 21 February 2014 at the Wayback Machine. The Oriental Institute identifies the subject as an Okapi with a question mark.
  4. ^ "Ethiopian Delegation, Apadana Staircase, Persepolis by Richard Stone". PBase. Retrieved 4 March 2023.
  5. ^ "First pictures of the okapi or the African 'unicorn'". ZME Science. 12 September 2008. Retrieved 20 February 2020.
  6. ^ "A New Deal for the Okapi, Africa's "Unicorn"". NRDC. 13 December 2019. Retrieved 20 February 2020.
  7. ^ "New hope for the elusive okapi, Congo's mini giraffe". Earth Touch News Network. Retrieved 9 November 2017.
  8. ^ a b Nowak, Ronald M. (1999) Walker's Mammals of the World. 6th ed. p. 1085.
  9. ^ Sclater, Philip Lutley (1901). "On an Apparently New Species of Zebra from the Semliki Forest". Proceedings of the Zoological Society of London. 1: 50–52 – via Biodiversity Heritage Library.
  10. ^ "okapi, n." Oxford English Dictionary. Retrieved 3 April 2020.
  11. ISBN 0292747071
  12. Proceedings of the Zoological Society of London
    . 2 (1): 1–5. 1901.(May to December)
  13. ISBN 9780226437224
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  14. ^
    ISBN 9780801871351
    .
  15. ^ Bohlin, B. (1926). "Die Familie Giraffidae: mit besonderer Berücksichtigung der fossilen Formen aus China". Palaeontologica Sinica, Series C. 4: 1–179.
  16. JSTOR 1374281
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  17. doi:10.1016/S0016-6995(86)80004-3
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  18. ISBN 978-0521121002
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  19. ^ Hunt, Kathleen. "Transitional Vertebrate Fossils FAQ Part 2C". TalkOrigins. Retrieved 28 April 2015.
  20. S2CID 6522531
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  21. ^ "Why Is the Okapi Called a Living Fossil". The Milwaukee Journal. 24 June 1954.[permanent dead link]
  22. PMID 27187213
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  23. ISBN 0789477645
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  24. ^ a b Palkovacs, E. "Okapi Okapia johnstoni". Animal Diversity Web. University of Michigan Museum of Zoology. Retrieved 17 April 2015.
  25. ^
    S2CID 253915266. Archived from the original
    (PDF) on 24 September 2015.
  26. S2CID 216556342
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  27. ^ a b Grzimek, B. (1990). Grzimek's Encyclopedia of Mammals (Volume 5). New York: McGraw-Hill Publishing Company.
  28. JSTOR 1381645
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  29. ^
    ISBN 978-1-4081-2251-8
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  30. JSTOR 1376381
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  31. ^ Lusenge, T.; Nixon, S. (2008). "Conservation status of okapi in Virunga National Park". ZSL Conservation Report. Zoological Society of London.
  32. ^ a b c Hart, J. A.; Hart, T. B. (1989). "Ranging and feeding behaviour of okapi (Okapia johnstoni) in the Ituri Forest of Zaire: food limitation in a rain-forest herbivore". Symposium of the Zoological Society of London. 61: 31–50.
  33. ^ "Okapia johnstoni (Okapi)". Animal Diversity Web.
  34. ^ "Okapi Conservation Strategy and Status Review" (PDF). www.giraffidsg.org. 21 February 2018. Archived from the original (PDF) on 21 February 2018. Retrieved 21 February 2018.
  35. PMID 10749434
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  36. ^ Jirik, Kate. "Okapia johnstoni Fact Sheet". ielc.libguides.com. San Diego Zoo Wildlife Alliance. Retrieved 28 August 2021.
  37. ^ "Rare okapi born in Rotterdam Zoo". Rotterdam Zoo. 2 September 2019. Archived from the original on 20 February 2020. Retrieved 20 February 2020.
  38. ^ Nixon, S. C.; Lusenge, T. (2008). Conservation status of okapi in Virunga National Park, Democratic Republic of Congo. ZSL Conservation Report No. 9 (PDF). London: The Zoological Society of London. Archived from the original (PDF) on 25 August 2021. Retrieved 22 November 2018.
  39. S2CID 224839859
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  40. ^ Hebert, Amanda (26 November 2013). "Okapi Added to IUCN'S Endangered Species List". Jacksonville, Florida: Okapi Conservation Project. Retrieved 3 June 2014.
  41. ^ Flocken, J. (29 June 2012). "Tragic Losses in the Heart of Darkness". HuffPost. Retrieved 18 April 2015.
  42. ^ Jones, P. (3 April 2013). "Infamous elephant poacher turns cannibal in the Congo". Mongabay. Retrieved 16 July 2017.
  43. ^ "Okapi SSP and EEP International Meeting". Okapi Conservation Project. Wildlife Conservation Global. Archived from the original on 18 April 2015. Retrieved 18 April 2015.
  44. ^ "Of okapis and men: Antwerp Zoo helps preserve endangered species". Flanders Today. 12 August 2016. Archived from the original on 14 August 2016. Retrieved 27 May 2018.
  45. ^ "Okapi's Half-Century" (PDF). Zooquaria (85). EAZA: 7. Spring 2014. Retrieved 23 February 2021.
  46. ^ "Bronx Zoo Debuts Its Baby Okapi". WCSNewsroom. 27 July 2009. Retrieved 19 October 2018.
  47. ^ "Baby Okapi Makes Public Debut At Bronx Zoo". newyork.cbslocal.com. 8 November 2011. Retrieved 19 October 2018.
  48. ^ "Animals & Plants | Okapi". animals.sandiegozoo.org. Retrieved 4 October 2017.
  49. ^ Peterson, Karla (23 August 2017). "Endangered okapi born at San Diego Zoo". The San Diego Union-Tribune. Retrieved 23 February 2021.
  50. ^ "Brookfield Zoo Celebrates Its 28th Okapi Birth Since 1959". chicago.cbslocal.com. 26 May 2017. Retrieved 4 October 2017.
  51. ^ "Okapi arrives at Roosevelt Park Zoo". Minot Daily News. 15 September 2017. Archived from the original on 6 August 2020. Retrieved 18 May 2020.
  52. ^ "Okapi".
  53. ^ "Okapi Conservation Project | The Americas". okapiconservation.org. Archived from the original on 5 February 2021. Retrieved 13 May 2019.
  54. ^ "Helping to protect endangered species around the world". Bristol Zoo. 17 May 2019. Retrieved 23 February 2021.
  55. ^ "Rare Okapi Arrive at Yorkshire Wildlife Park". Yorkshire Wildlife Park. 17 May 2018. Retrieved 23 February 2021.
  56. ^ "Okapi Conservation Project | Europe". okapiconservation.org. Archived from the original on 1 December 2017. Retrieved 25 November 2017.
  57. ^ "Okapi Conservation Project | Asia". okapiconservation.org. Archived from the original on 5 February 2021. Retrieved 13 May 2019.

Further reading

External links

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