African elephant

African elephants[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Proboscidea
Family: Elephantidae
Genus: Loxodonta
Anonymous, 1827
Species

L. adaurora (Maglio 1970a) †

ssp. adaurora (Maglio 1970) †
ssp. kararae (Beden 1983) †

L. africana (Blumenbach, 1797)
L. atlantica (Pomel, 1879) †

ssp. angammensis (Coppens, 1965) †
ssp. atlantica (Pomel, 1879) †

L. cyclotis (Matschie, 1900)
L. exaptata (Dietrich 1941) †
Distribution of Loxodonta africana (2007)

African elephants are the species of elephants in the genus Loxodonta (Greek for 'oblique-sided tooth'[2]), one of the two existing genera in Elephantidae. Although it is commonly believed that the genus was named by Georges Cuvier in 1825, Cuvier spelled it Loxodonte. An anonymous author romanized the spelling to Loxodonta and the ICZN recognizes this as the proper authority.[1]

Fossil Loxodonta have only been found in Africa, where they developed in the middle Pliocene.

Contents

Size

Both African elephant species are bigger than the Asian Elephant. Males stand 3.6 m (12 ft) tall at the shoulder and weigh 5,400 kg (12,000 lb), while females stand 3 m (9.8 ft) and weigh between 3,600 and 4,600 kg (7,900 and 10,000 lb).[3] However, males can get as big as 6,800 kg (15,000 lb).

Teeth

A female African Bush Elephant in the Roger Williams Zoo, Providence, RI

Elephants have four molars; each weighs about 5 kg (11 lb) and measures about 30 cm (12 in) long. As the front pair wear down and drop out in pieces, the back pair shift forward and two new molars emerge in the back of the mouth. Elephants replace their teeth six times. At about 40 to 60 years of age the elephant no longer has teeth and will likely die of starvation, a common cause of death.

Their tusks are teeth; the second set of incisors become the tusks. They are used for digging for roots and stripping the bark off trees for food, for fighting each other during mating season, and for defending themselves against predators. The tusks weigh from 23–45 kg (51–99 lb) and can be from 1.5–2.4 m (5–8 ft) long. Unlike Asian elephants, both male and female African elephants have tusks.[4] The enamel plates of the molars are fewer in number than in Asian elephants.[5]

Species

Bush and Forest Elephants were formerly considered subspecies[6] of the same species Loxodonta africana. As described in the entry for the Forest Elephant in the third edition of Mammal Species of the World (MSW3)[7], there is now evidence that they should be considered as separate species, but also some recent evidence to the contrary, and the question remains undecided at present.

Much of the evidence cited in MSW3 is morphological. The African Forest Elephant has a longer and narrower mandible, rounder ears, a different number of toenails, straighter and downward tusks, and considerably smaller size. With regard to the number of toenails: the African Bush Elephant normally has 4 toenails on the front foot and 3 on the hind feet, the African Forest Elephant normally has 5 toenails on the front foot and 4 on the hind foot (like the Asian elephant), but hybrids between the two species commonly occur.

MSW3 lists the two forms as full species[1] and does not list any subspecies in its entry for Loxodonta africana[8]. However, this approach is not taken by the United Nations Environment Programme's World Conservation Monitoring Centre nor by the International Union for Conservation of Nature (IUCN), both of which list L.cyclotis as a synonym (not even a subspecies) of L.africana[9][10]

A consequence of the IUCN taking this view is that the IUCN Red List makes no independent assessment of the conservation status of the two forms of African elephant. It merely assesses the two forms taken together as a unit as vulnerable[10].

Conservation

Men with African elephant tusks, Dar es Salaam, c. 1900
African elephant in Ramat Gan Safari.

Poaching significantly reduced the population of Loxodonta in certain regions during the 20th century. An example of this poaching pressure is in the eastern region of Chad—elephant herds there were substantial as recently as 1970, with an estimated population of 400,000; however, by 2006 the number had dwindled to about 10,000. The African elephant nominally has governmental protection, but poaching is still a serious issue.[11]

Human encroachment into or adjacent to natural areas where bush elephants occur has led to recent research into methods of safely driving groups of elephants away from humans, including the discovery that playback of the recorded sounds of angry honey bees are remarkably effective at prompting elephants to flee an area.[12] Some elephant communities have grown so large, in Africa, that some communities have resorted to culling large amounts to help sustain the ecosystem.[13]

See also

Ivory trade

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Shoshani, Jeheskel (16 November 2005). "Genus Loxodonta". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). p. 91. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=11500008. 
  2. ↑ 2.0 2.1 2.2 2.3 Kalb, Jon E.; Assefa Mebrate (1993). Fossil Elephantoids from the Hominid-Bearing Awash Group, Middle Awash Valley, Afar Depression, Ethiopia. Independence Square, Philadelphia: The American Philosophical Society. pp. 52–59. ISBN 0-87169-831-5. http://books.google.com/books?id=AOzn0vdaDgUC&lpg=PA53&ots=OCPoM5tSar&dq=Loxodonta%20adaurora&pg=PA59#v=onepage&q=Loxodonta%20adaurora&f=false. 
  3. ↑ <[1]>
  4. ↑ <http://www.denverzoo.org/animals/asianElephant.asp>
  5. ↑ Clutton-Brock, Juliet (1987). A Natural History of Domesticated Mammals. p. 208. ISBN 0521346975. 
  6. ↑ Estes, Richard D. (1999). The Safari Companion. Chelsea Green Publishing Company. p. 223. ISBN 1890132446. 
  7. ↑ Shoshani, Jeheskel (16 November 2005). "Loxodonta cyclotis". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=11500010. 
  8. ↑ Shoshani, Jeheskel (16 November 2005). "Loxodonta africana". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=11500009. 
  9. ↑ UNEP-WCMC database entry for Loxodonta cyclotis
  10. ↑ 10.0 10.1 Blanc, J. (2008). Loxodonta africana. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.1. Downloaded on 10 June 2010.
  11. ↑ Goudarzi, Sara (2006-08-30). "100 Slaughtered Elephants Found in Africa". LiveScience.com. http://www.livescience.com/animalworld/060830_chad_elephants.html. Retrieved 2006-08-31. 
  12. ↑ Lucy E. King, Iain Douglas-Hamilton, Fritz Vollrath (2007) African elephants run from the sound of disturbed bees. Current Biology 17: R832-R833
  13. ↑ Wilson, Sam (2005-11-06). "Africa | Elephant explosion triggers cull row". BBC News. http://news.bbc.co.uk/1/hi/world/africa/4392800.stm. Retrieved 2009-11-22. 

External links