The distinctive-looking little mammals in the African family Macroscelididae are known as elephant shrews or (from the Swahili) sengis. Despite the name, elephant shrews are not closely related to shrews--in fact, they are members of the Afrotheria and therefore more closely related to elephants (Seiffert 2007 and references therein)!
Elephant shrews are the size of mice or rats, ranging in length from 100 to 300 mm and in weight from 25 to 700 g. They have large eyes and ears, slender limbs, and a long, bare tail. A long tubular snout protruding from a strongly tapered skull accounts for the name "elephant shrew". All living elephant shrew species are specialized invertebrate-feeders, often feeding on ants especially. The fine-boned "soft-furred elephant shrew" lineage (subfamily Macroscelidinae) and the more robust "giant elephant shrew" lineage (subfamily Rhynchocyoninae) apparently diverged at least 25 to 35 million years ago. The macroscelidines are superficial surface-gleaners of small invertebrates (and occasionally fruits and seeds) in shaded but dry environments; the rhynchocyanines (represented only by Rhynchocyon) are found in moister habitats. where they forage for invertebrates by actively turning over leaf litter. Elephant-shrew species that have been studied are all socially monogamous, an unusual trait among mammals. (Kingdon 1997; Smit et al. 2011 and references therein)
The long, powerful hindlegs of elephant shrews ("Macroscelididae" means "big thigh") allow them to make vertical leaps from a standing position and to sustain their rapid, bounding escape from potential predators. Elephant shrews are almost exclusively diurnal. Reliance on shelters or burrows varies among species, but the giant elephant shrews use dry leaf litter to construct multiple 1 m-wide leaf mound shelters which they pile over shallow body-sized scoops in the soil. These mounds, which are constructed in the early morning, are used mainly as night shelters and as nurseries for their offspring. (Kingdon 1997; Smit et al. 2011 and references therein)
The family Macroscelididae as typically treated includes four genera and 17 species. The genera Macroscelides and Petrodromus are monotypic (i.e., each includes just a single species, the former a southwestern African gravel plain specialist and the latter having a southern, eastern, and central African distribution characterized by a wide habitat tolerance). Rhynchocyon includes four forest species found in eastern and central Africa (including one, R. udzungwensis, discovered only in 2005 and formally described by Rovero et al. in 2008) and Elephantulus includes 11 species with a range of habitat associations (including one, E. pilicaudus, that was formally recognized as distinct from E. edwardii, by Smit et al., only in 2008). Of all the elephant shrews, only E. rozeti occurs north of the Sahara (Smit et al. 2011). Recent investigations have supported the earlier suggestion that Elephantulus, as currently described, is not monophyletic (i.e., this group does not include all the descendants of the shared ancestor) and that there are grounds for subsuming Petrodromus and Macroscelides in Elephantulus (Douady et al. 2003; Smit et al. 2011).
- Douady, C.J., F. Catzeflis, J. Raman, M.S. Springer, and M.J. Stanhope. 200). The Sahara as a vicariant agent, and the role of Miocene climatic events, in the diversification of the mammalian order Macroscelidea (elephant shrews). Proceedings of the National Academy of Sciences (U.S.A.) 100: 8325–8330.
- Kingdon, J. 1997. The Kingdon Field Guide to African Mammals. Academic Press, San Diego.
- Rovero, F., G. B. Rathbun, A. Perkin, T. Jones, D. O. Ribble, C. Leonard, R. R. Mwakisoma, and N. Doggart. 2008. A new species of giant sengi or elephant-shrew (genus Rhynchocyon) highlights the exceptional biodiversity of the Udzungwa Mountains of Tanzania. Journal of Zoology 274: 126-133.
- Seiffert, E. 2007. A new estimate of afrotherian phylogeny based on simultaneous analysis of genomic, morphological, and fossil evidence. BMC Evolutionary Biology 7: 13.
- Smit, H.A., T.J. Robinson, J. Watson, and B.J. van Vuuren. 2008. A new species of elephant-shrew (Afrotheria: Macroselidea: Elephantulus) from South Africa. Journal of Mammalogy 89 (5): 1257–1269.
- Smit, H.A., B.J. van Vuuren, P.C.M. O'Brien, M. Ferguson-Smith, F. Yang, and T.J. Robinson. 2011. Phylogenetic relationships of elephant-shrews (Afrotheria, Macroscelididae). Journal of Zoology 284: 133-143.
Sengis according to MammalMAP
Believe it or not, according to most biologists the sengi (family Macroscelididae), or elephant shrew, is related to the elephant, and not the shrew, as previously believed because of their superficial resemblance. Sengis are grouped together in the superorder Afrotheria with elephants and other African mammals like the sea cows, hyraxes, tenrecs, golden moles and aardvarks.
17 recognised species of sengis are spread out over 6 African countries exclusively, and can be found in almost any type of habitat, from thick forests and woodlands to savannahs and deserts, depending on the species.Even though body proportions are quite similar and size can vary from 22 to 30 cm, the sengi’s weight can range from 25 grams for Macroscelides species to 700 grams forRhynchocyon species, which includes the largest as well as the most colourful sengis – like the one pictured above. They are called elephant shrews because of their long, trunk-like noses, which they use to smell out those tasty creepy crawlies. The sengi has long, slim limb bones adapted for running, a hunchbacked posture and a long tail. The diet of a sengi is made up almost entirely out of insects like grubs, spiders, beetles, termites and ants, and unlike many other small mammals, most species are diurnal and spend their waking hours during dusk and dawn, out and about munching yummy bugs. Elephant shrews are monogamous and mate for life! They don’t actually spend that much time together, but have scented trails to check up on each other’s whereabouts. These trails are also used to easily escape their predators, which may include birds of prey, big lizards and snakes (watch the video here!). Sengis are not very friendly towards strangers, and will perform all kinds of dramatic acts including screaming, snapping and kicking to drive away the unwanted neighbours. Females give birth four or five times a year to fully haired, well developed new-borns, after a gestation period of about 2 months.
According to the IUCN Red List of mammals, most of the sengi species are considered as ‘Least Concern’. Three of the Elephantulus species are listed as ‘Data Deficient’ while all four species of giant sengis are at risk (one ‘Endangered’, two ‘Vulnerable’ and another ‘Near Threatened’). Forest fragmentation is the main threat in all cases, while subsistence hunting for food may also play a role in some areas.
Sometimes called the jumping shrew, some sengi species, like the checkered elephant shrew, can leap almost one metre into the air!
Rathbun, G.B. Sengis (Elephant-Shrews) In: Ornithology & Mammalogy, California Academy of Sciences
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Mcathur, Y. Awesome Facts About Elephant Shrews
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Molecular Biology and Genetics
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Elephant shrews, or jumping shrews, are small insectivorous mammals native to Africa, belonging to the family Macroscelididae, in the order Macroscelidea, whose 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 shrews (family Soricidae) in the order Insectivora. Nonetheless, elephant shrews are not classified with the superficially similar true shrews, but are in fact more closely related to elephants and their kin within the newly recognized Afrotheria; the biologist Jonathan Kingdon has proposed they instead be called sengis, 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 semiarid, mountainous country in the far northwest of the continent.
Elephant shrews are small, quadrupedal, insectivorous mammals resembling rodents or opossums, with scaly tails, elongated snouts, and rather long legs for their size, which are used to move in a hopping fashion like rabbits. They vary in size from about 10 cm to almost 30 cm, from just under 50 g to over 500 g. The short-eared elephant shrew has an average size of 150 mm (5.9 in). Although the size of the trunk varies from one species to another, all are able to twist it about in search of food. Their lifespans are about two and a half to four years in the wild.[page needed] They have large canine teeth, and also high-crowned cheek teeth like those of ungulates. Their dental formula is 1-22.214.171.124
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 they mark using scent glands. Rhynchocyon species also dig small conical holes in the soil, bandicoot-style, but others may make use of natural crevices, or make leaf nests.
Short-eared elephant shrews inhabit the dry steppes and stone deserts of southwestern Africa. They can even be found in the Namib Desert, one of the driest regions of the earth. 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.
Female elephant shrews undergo a menstrual cycle similar to that of human females and the species is one of the very few nonprimate mammals to do so. The elephant shrew mating period lasts for several days. After mating, the pair will return to their solitary habits. After a gestation period varying from 45 to 60 days, the female will give birth to litters of one to three young several times a year. The young are born relatively well developed, but remain in the nest for several days before venturing outside.
After five days, the young's milk diet is supplemented with mashed insects, which are collected and transported in the cheek pouches of the female. The young then slowly start to explore their environment and hunt for insects. After about 15 days, the young will begin the migratory phase of their lives, 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.
Elephant shrews mainly eat 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 an 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.
A number of fossil species are known, all of them from Africa. They were separate from the similar-appearing order Leptictida. A considerable diversification of macroscelids occurred in the Paleogene. Some, such as Myohyrax, were so similar to hyraxes, 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. Although macroscelids have been classified with many groups, often on the basis of superficial characteristics, considerable morphological and molecular evidence now indicates placing them within Afrotheria, probably close to the base of Paenungulata.
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 that unites elephant shrews with tenrecs and golden moles as well as certain mammals previously presumed to be ungulates, including hyraxes, sirenians, aardvarks and elephants.
- ORDER MACROSCELIDEA
- Family Macroscelididae
- Genus Elephantulus
- Short-snouted elephant shrew, E. brachyrhynchus
- Cape elephant shrew, E. edwardii
- Dusky-footed elephant shrew, E. fuscipes
- Dusky elephant shrew, E. fuscus
- Bushveld elephant shrew, E. intufi
- Eastern rock elephant shrew, E. myurus
- Karoo rock elephant shrew, E. pilicaudus
- Somali elephant shrew, E. revoili
- North African elephant shrew, E. rozeti
- Rufous elephant shrew, E. rufescens
- Western rock elephant shrew, E. rupestris
- Genus Macroscelides
- Genus Petrodromus
- Genus Rhynchocyon
- Genus Elephantulus
- Family Macroscelididae
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