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Cladus: Eukaryota Name Macroscelidea Butler, 1956 Vernacular names
----- Elephant shrews or jumping shrews are small insectivorous mammals native to Africa, belonging to the Macroscelididae family, in the order Macroscelidea. Their traditional common English name comes from a fancied resemblance between their long noses and the trunk of an elephant, and an assumed relationship with the true shrews (family Soricidae) in the order Insectivora because of their superficial similarities. As it has become plain that the elephant shrews are unrelated to the shrews, the biologist Jonathan Kingdon has proposed that they instead be called sengis[3], a term derived from the Bantu languages of Africa. They are widely distributed across the southern part of Africa, and although common nowhere, can be found in almost any type of habitat, from the Namib Desert to boulder-strewn outcrops in South Africa to thick forest. One species, the North African Elephant Shrew, remains in the semi-arid, mountainous country in the far north-west of the continent. Dentition Although mostly diurnal and very active, they are difficult to trap and very seldom seen: elephant shrews are wary, well camouflaged, and adept at dashing away from threats. Several species make a series of cleared pathways through the undergrowth and spend their day patrolling them for insect life: if disturbed, the pathway provides an obstacle-free escape route. Elephant shrews are not highly social animals, but many live in monogamous pairs, which share and defend a home territory, which they mark using scent glands[5]. The Rhynchocyon species also dig small conical holes in the soil, bandicoot style, but others may use natural crevices, or make leaf nests. Short-eared elephant-shrews inhabit dry steppes and stone deserts of Southwestern Africa. They even can be found in the Namib-desert, one of the driest regions of the earth. Elephant-shrews live in pairs and defend territories. Females drive away other females while males try to ward off other males. Although they live in pairs, the partners do not care much for each other and their sole purpose of even associating with the opposite sex is for reproduction. Social behaviors are not very common and they even have separate nests. The one or two young are well developed at birth. They are able to run around just a few hours after birth.[6] Females give birth to litters of one or three young several times a year, after a gestation period varying from 45 to 60 days. The young are born relatively well developed, but remain in the nest for several days before venturing outside[5]. The mating period lasts for several days and is followed by six weeks of gestation. After mating, the pair will return to their solitary habits. The female then will give birth to 1-2 young in one of her leaf nests. Only for nursing purposes are the young visited by the mother. After 5 days the young are fed mashed insects with the milk, which are collected and transported in the cheek pouches of the female. The young then slowly start to explore their environment and start to hunt for insects. After about 15 days, the young will begin the migratory phase of their life which lessens the dependency of the young on their mother. The young will then establish their own home ranges (about 1 km2) and will become sexually active within 41–46 days.[7][8] Feeding habits All elephant-shrews eat mainly invertebrates, such as insects, spiders, centipedes, millipedes, and earthworms. An elephant-shrew uses its nose to find prey and uses its tongue to flick small food into its mouth, much like an anteater. Eating large prey can pose somewhat of a challenge for the elephant shrew. For example, a giant elephant-shrew struggling with an earthworm must first pin its prey to the ground with a forefoot. Then, turning its head to one side, it chews pieces off with its cheek teeth, much like a dog chewing a bone. This is a sloppy process, and many small pieces of worm drop to the ground; these are simply flicked up with the tongue. Some elephant-shrews also feed on small amounts of plant matter when available, especially new leaves, seeds, and small fruits.[7] Evolution A number of fossil species are known, all of them from Africa. There was a considerable diversification of macroscelids in the early tertiary period. Some, such as Myohyrax, were so similar to hyraxes that they were initially misidentified as belonging to that group, while others, such as Mylomygale were relatively rodent-like. These unusual forms all died out by the Pleistocene[2]. Although macroscelids have been classified with many groups, often on the basis of superficial characteristics, there is now considerable morphological and molecular evidence for placing them within Afrotheria, probably close to the base of Paenungulata. Classification In the past, elephant shrews have been classified with the shrews and hedgehogs as part of the Insectivora; regarded as distant relatives of the ungulates; grouped with the treeshrews; and lumped in with the hares and rabbits in the Lagomorpha. Recent molecular evidence, however, strongly supports a superorder Afrotheria which unites tenrecs, and golden moles with certain ungulates or mammals that were previously presumed to be ungulates, including hyraxes, sirenians, aardvarks and elephants, as well as the elephant shrews. Notes 1. ^ a b Schlitter, Duane A. (2005-11-16). Wilson, D. E., and Reeder, D. M.. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 82-85. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3. References * Murata Y, Nikaido M, Sasaki T, Cao Y, Fukumoto Y, Hasegawa M, Okada N. Afrotherian phylogeny as inferred from complete mitochondrial genomes. Mol Phylogenet Evol. 2003 Aug;28(2):253-60. Source: Wikispecies, Wikipedia: All text is available under the terms of the GNU Free Documentation License |
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