Pygmy hippopotamus
| Pygmy Hippopotamus | |
|---|---|
| |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Order: | |
| Family: | |
| Genus: | |
| Species: | C. liberiensis
|
| Binomial name | |
| Choeropsis liberiensis | |
| Subspecies | |
The Pygmy Hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis) is a large mammal native to the forests and swamps of western Africa (the species name, meaning "of Liberia", reflects this). The pygmy hippo is a herbivore and also nocturnal. It is one of only two extant species in the hippopotamus family. Unlike its larger relative, the Hippopotamus, relatively little is known about the pygmy hippo's diet or behaviour, although it is clear that the pygmy hippo is adapted to forest environments rather than the more open plains and grasslands that the hippopotamus prefers.
Physiology & behaviour
Pygmy hippos stand about 75 cm (30 inches) high at the shoulder and weigh 180 kilograms (400 pounds). They are more solitary than their larger relatives and considerably less aquatic. The skin is greenish-black, shading to a creamy gray on the lower body. The average lifespan is 35 years, and one in captivity reached the age of 42. The gestation period ranges from 190-210 days, and usually a single young is born. Pygmy hippos live either alone or in small groups, typically a mated pair and one calf.
All species of hippo spend most of their time in the water, emerging mainly at night in order to feed on land. The pygmy hippo is half as tall as the hippopotamus and weighs 1/10 as much as a small member of the larger hippo species. The fossil record suggests that the pygmy hippo is closer in form and possibly behaviour to the common ancestor.
Taxonomy
The taxonomy of the genus of the pygmy hippopotamus is disputed. Pygmy hippos may be classified as either Choeropsis liberiensis or Hexaprotodon liberiensis. Either way, the pygmy hippo is the only extant member of its genus. If the pygmy hippo is a member of Hexaprotodon then it is closely related to a number of prehistoric species of hippos that lived in Asia.[2]
There are two subspecies of pygmy hippopotamus. Choeropsis liberiensis liberiensis (or Hexaprotodon liberiensis liberiensis) ranges in Guinea, Sierra Leone, Liberia and Côte d'Ivoire. All research on living pygmy hippos is from this subspecies.
The other population, Choeropsis liberiensis heslopi, with a different shape to the skull, ranged until recently in the Niger Delta but is believed to be extinct. If this subspecies still exists, it would be separated by over 1800 km and the Dahomey Gap, a region of desert that divides the forest regions of West Africa. The species is named after I.R.P. Heslop, who claimed in 1945 to have shot a pygmy hippo in the Niger Delta region and collected several skulls. He estimated that perhaps no more than 30 pygmy hippos remained in the region. The animal is likely extinct, and some researchers have questioned whether there is sufficient evidence to confirm that the species ever existed at all.[3]
Origins
Prehistoric species
Several species of pygmy hippos have become extinct. The Cyprus Dwarf Hippopotamus (Hippopotamus minor) and the Cretan Dwarf Hippopotamus (Hippopotamus creutzburgi) existed on the island of Cyprus and Crete respectively until the Late Pleistocene or Holocene. Although these species are often called pygmy hippos, they are classified as a separate genus.
Several species of pygmy hippos also have gone extinct on the island of Madagascar, including the Madagascan Dwarf Hippopotamus and the Madagascan Pygmy Hippopotamus.
Distribution and habitat
Conservation
In 2007, the Evolutionarily Distinct and Globally Endangered (EDGE) project was begun, to help try to protect some of the worlds most 'unique' species. The term 'unique' in this case refers to animals that have few if any closely related species, are genetically distinct in some way, and that require the immediate action of man to prevent their extinction.[4]
564 species were named 'unique', and EDGE chose to try to protect the top 100 species. Of these 100 species, the pygmy hippopotamus was one of the top 10 chosen as a "focal species" to try to help first with the project, along with the following:
- Attenborough's long-beaked echidna
- Hispaniolan solenodon
- Bactrian camel
- Yangtze River dolphin
- Slender loris
- Hirola antelope
- Golden-rumped elephant shrew
- Bumblebee bat
- Long-eared jerboa
Pygmy hippos in captivity
Although threatened in the wild, pygmy hippos breed freely in zoos. Between 1970 and 1991 the population of pygmy hippos born in captivity more than doubled. The survival of the species in zoos is more certain than the survival of the species in the wild.[5] [6] In captivity, the pygmy hippo lives from 42-55 years, longer than in the wild.[7]
The first pygmy hippo was brought to Europe in 1873 after being captured in Sierra Leone by a member of the British Colonial Service but died shortly after arrival. Pygmy hippos were successfully introduced to Europe in 1911. They were first shipped to Germany and then to the Bronx Zoo in New York City where they also thrived.[7]
In 1927, Harvey Firestone of Firestone Tires presented, Billy the pygmy hippo, to U.S. President Calvin Coolidge. Billy lived at the Smithsonian National Zoological Park and according to the zoo, is a common ancestor to most pygmy hippos in U.S. zoos today.[6]
References
- ^ "ITIS on Hexaprotodon liberiensis". Integrated Taxonomic Information System. Retrieved 2004-08-11.
- ^ Boisserie, Jean-Renaud (2005). "The phylogeny and taxonomy of Hippopotamidae (Mammalia: Artiodactyla): a review based on morphology and cladistic analysis". Zoological Journal of the Linnean Society. 143: 1–26. Retrieved 2007-06-01.
- ^ "Pigs, Peccaries and Hippos Status Survey and Action Plan". World Conservation Union status survey. 1993. Retrieved 2007-05-22.
- ^ "Protection for 'weirdest' species". BBC. 2007-01-16. Retrieved 2007-05-22.
- ^ S. Keith Eltringham (1993). "Pigs, Peccaries and Hippos Status Survey and Action Plan". IUCN.
- ^ a b "Pygmy Hippo fact sheet". Smithsonian National Zoological Park. Retrieved 2007-05-22.
- ^ a b S. Keith Eltringham. "The Hippos". ISBN 085661131X.
External links
- EDGE of Existence Programme
- EDGE Species
- EDGE of Existence (Hexaprotodon liberiensis) - Saving the World's most Evolutionarily Distinct and Globally Endangered (EDGE) species
- Template:IUCN2006