Hyena
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| Spotted Hyena | |
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| Family: | Hyaenidae Gray, 1821
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Hyenas or Hyænas are moderately large terrestrial carnivores native to Africa, Arabia, Asia and the Indian subcontinent. They are members of the family Hyaenidae. The family comprises four species, the Aardwolf, Brown Hyena, Spotted Hyena, and Striped Hyena.
Appearance & Biology
Although hyenas bear some physical resemblance to canids, they make up a separate biological family that is most closely related to Herpestidae (the family of mongooses and meerkats). All species have a distinctly bear-like gait due to their front legs being longer than their back legs. The aardwolf, striped hyena and brown hyena have striped pelts and manes lining the top of their necks which erect when frightened. The spotted hyena's fur is considerably shorter and is spotted rather than striped. Unlike other species, its mane is reversed forwards. Spotted hyenas have a strong bite proportional to their size, but the view that they have the strongest bite is a myth, and a number of other animals (including the Tasmanian devil) have proportionately stronger bites.[1][2]
Spotted Hyenas, and, to a lesser extent, Striped and Brown Hyenas, have powerful carnassial teeth adapted for cutting flesh and crushing premolars for crushing bone. The Aardwolf has greatly reduced cheek teeth, that are sometimes absent in the adult, but otherwise has the same dentition as the other three species.[3] The dental formula for all hyena species is:
| Dentition |
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| 3.1.4.1 |
| 3.1.3.1 |
Hyenas are highly intelligent animals, and some scientists claim they are of equal intelligence to certain apes.[4] One indication of hyena intelligence is that they will move their kills closer to each other to protect them from scavengers; another indication is their strategic hunting methods.[5]
The majority of hyena species show little sexual dimorphism, usually with males being only slightly larger than the females. The spotted hyena is an exception to this as females are larger than the males. One unusual feature of the spotted hyena is that females have an enlarged clitoris called a pseudo-penis, demi-penis or sometimes mistakenly referred to as a nanophallus. Female hyenas give birth, copulate, and urinate through their protruding genitalia, which stretches to allow the male penis to enter for copulation, and it also stretches during birth. The anatomical position of the genitalia gives females total sexual control over who is allowed to mate with them. Researchers originally thought that one cause of this characteristic of the genitals was androgens that were introduced to the fetus very early on in its development. However, it was discovered that when the androgens were held back from the fetus, the development of the female genitalia was not altered.[citation needed]
Adult females are the most powerful and dominating members of the Clan, then come female cubs, and at last males.
All species excrete an oily, yellow substance from their anal glands onto objects to mark their territories. When scent marking, the anal pouch is turned inside out, or everted. Hyenas also do this as a submissive posture to more dominant hyenas. Genitals, the anal area, and the anal glands are sniffed during greeting ceremonies in which each hyena lifts its leg and allows the other to sniff its anal sacks and genitals. All four species maintain latrines far from the main denning area where dung is deposited. Scent marking is also done by scraping the ground with the paws, which deposits scent from glands on the bottoms of the feet. Hyenas do not raise their legs when urinating as male or dominant canids do.[6]
Unlike the canids, hyenas do not regurgitate or carry back food for their young.[6]
Evolution
The oldest remains of hyenas are from the european early Miocene (ca. 17 Ma), slightly later they appear in the african fossil record. The first hyenas, which appeared in the middle Miocene were civet-like tree dwellers like Protictitherium and Ictitherium.
Some other Miocene genera (e.g. Percrocuta, Dinocrocuta), which were formerly included also in the hyena family are placed in a separate family today, the Percrocutidae. Some Percrocutids looked similar to modern bone cracking hyenas and resembled them probably ecologically. Since the later Miocene the Percrocutids disappeared and the hyenas gave rise to larger forms. Among them were also speedy species, like Chasmaporthetes developed to run down prey, along with even more powerfully developed bone crushing species, like Adcrocuta similar to modern hyenas.[7]
The hyena's peak was during the Pleistocene, with 4 genera and 9 species of hyena.[8] Among them was Pachycrocuta brevirostris, the largest Hyena which ever lived. Their success was probably largely due to the fact that the sabre-toothed cats which they coexisted with, were unable to make full use of their prey due to the nature of their dentition.
The hyena's powerful jaws and digestive systems allowed them to consume otherwise undigestible parts.[8] As the sabre-toothed cats began to die out and be replaced by short fanged felids which were more efficient eaters, some hyenas began to hunt for themselves and began evolving into new species, the modern spotted hyena being among them.[9]
Most lines of hyena died out towards the end of the Miocene, possibly due to competition from early canids. The running hyena Chasmaporthetes survived until the first ice ages, and the Eurasian Cave Hyena survived until the end of the last ice age, when they died out along with much of the Eurasian megafauna.
Habitat
With the exception of the Striped Hyena which has been seen in the jungles of India, all modern Hyena species generally reside in arid environments like African savannahs and deserts.
Dietary habits
Except for the Aardwolf, all hyena species are efficient scavengers as well as hunters.[citation needed] They have extremely strong jaws in relation to their body size and have a very powerful digestive system with highly acidic fluids, making them capable of eating and digesting their entire prey, including skin, teeth, horns, bones and even hooves. Since they eat carrion, their digestive system deals very well with bacteria.
The spotted hyena is primarily a predator, unlike its cousins. Spotted hyenas are successful pack hunters of small to large sized ungulates and are the most abundant carnivore on the African continent.
The Aardwolf is a specialised feeder of termites, thus lacking the size and physical power of its cousins.
In culture
Negative associations have generally stemmed from Hyenas' tendency to scavenge graves for food. They are one of the few creatures naturally suited for this due to their ability to devour and digest every part of a carcass, including bone. As such, many associate hyenas with gluttony, uncleanliness, and cowardice.
Their haunting laughter-like calls inspired the idea in local cultures that they could imitate human voices and call their victims by name. Hyenas are also associated with divination and sometimes thought of as tools of demons and witches. In African folklore, witches and sorcerers are thought to ride hyenas, or even turn into them.
African attitudes toward hyenas are little better than those held in the European cultures. Most African tribes view hyenas as inedible and greedy hermaphrodites. The Bouda is a mythical tribe reputed to house members able to transform into hyenas.[8] Belief in "Werehyenas" is so entrenched within the traditional lore of the Bornu people of north-eastern Nigeria, that their language even contains a special word bultungin which translates as "I change myself into a hyena".[10]
Early naturalists thought hyenas were hermaphrodites or commonly practiced homosexuality, largely due to the female spotted hyena's unique urogenital system. According to early writings such as Ovid's Metamorphoses and the Physiologus, the hyena continually changed its sex and nature from male to female and back again. In Paedagogus, Clement of Alexandria noted that the hyena (along with the hare) was "quite obsessed with sexual intercourse." Many Europeans associated the hyena with sexual deformity, prostitution, and deviant sexual behavior.
References
- ^ Ancient Worlds News - Marsupial has the deadliest bite - 04/04/2005
- ^ Wroe, S, McHenry, C, and Thomason, J. (2005). "Bite club: comparative bite force in big biting mammals and the prediction of predatory behaviour in fossil taxa". Proceedings of the Royal Society B-Biological Sciences. 272: 619–625.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Richardson, Philip K.R. & Bearder, Simon (1984). Macdonald, D. (ed.). The Encyclopedia of Mammals. New York: Facts on File. pp. 154–159. ISBN 0-87196-871-1.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Said by biologist Jeff Corwin, in an episode of "The Jeff Corwin Experience" concentrating on spotted hyenas
- ^ Lind, Hans. "Bogen om Dyrepsykologi".
- ^ a b Kruuk, Hans (1972). The Spotted Hyena: A study of predation and social behaviour. pp. pp.335. 0563208449.
{{cite book}}:|pages=has extra text (help) - ^ Alan Turner & Mauricio Anton: Evolving Eden. An Illustrated Guide to the Evolution of the African Large-Mammal Fauna. Columbia University Press, New York, 2004. ISBN 0-231-11944-5
- ^ a b c "Hyaenidae". Retrieved 2007-05-31. Cite error: The named reference "AP" was defined multiple times with different content (see the help page).
- ^ Denis-Huot, Christine & Denis-Huot, Michel (2003). The Art of being a Lion. pp. pp.224. ISBN 158663707X.
{{cite book}}:|pages=has extra text (help)CS1 maint: multiple names: authors list (link) - ^ lycaon
See also
External links
- IUCN Conservation Union Hyaendiae Specialist Group
- Hyena: Wildlife summary from the African Wildlife Foundation
- Robin M. Weare's Hyena pages
- Excerpt about hyenas from Richard D. Estes's "The Safari Companion" (ISBN 1-890132-44-6)
- A mechanism for virilization of female spotted hyenas in utero
- evolution of the family
- Quick Guide - Spotted hyena (deals with intelligence and social interaction)