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).
Believe it or not, according to most biologists the sengi(familyMacroscelididae), 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 forMacroscelidesspecies to 700 grams forRhynchocyonspecies, 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 videohere!). 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 theElephantulusspecies 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.
Interesting fact:
Sometimes called the jumping shrew, some sengi species, like the checkered elephant shrew, can leap almost one metre into the air!
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