Elephant shrews, also called jumping shrews or sengis, are small insectivorousmammals native to Africa, belonging to the family Macroscelididae, in the orderMacroscelidea. Their traditional common English name "elephant shrew" comes from a perceived resemblance between their long noses and the trunk of an elephant, and their superficial similarity with shrews (family Soricidae) in the order Eulipotyphla. However, phylogenetic analysis has revealed that elephant shrews are not properly classified with true shrews, but are in fact more closely related to elephants than to shrews.[4] In 1997, the biologist Jonathan Kingdon proposed that they instead be called "sengis" (singular sengi),[5] a term derived from the Bantu languages of Africa, and in 1998, they were classified into the new clade Afrotheria.[6]
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 northwest of Africa. The Somali elephant shrew went unobserved from 1968 to 2020 but was rediscovered by a group of scientists in Djibouti.[7]
Characteristics
The creature is one of the fastest small mammals, having been recorded to reach speeds of 28.8 kilometres per hour (17.9mph).[8] Compared to other mammalian insectivores, sengis have relatively large brains.[9] They are solitary animals which means that they rely on a combination of vocalizations and scent markings for communication with their vocalizations, which serves the purposes such as territory defense and mate attraction.[10]
Elephant shrews are small, quadrupedal, insectivorous mammals resembling rodents or opossums, with scaly tails, long snouts, and legs quite long for their size, which are used to move from one place to another like rabbits. They vary in size from about 10 to 30 centimetres (3.9 to 11.8in), from 50 to 500 grams (1.8 to 17.6oz).The body weight of the grey-faced sengi is about 700 g, which is 25–50% greater than any other giant sengi. The new Rhynchocyon is only known from two populations that cover about 300 km2 of montane forest. It has an estimated density of 50–80 individuals km−2 The short-eared elephant shrew has an average size of 150mm (5.9in). Although the size of the trunk varies among species, 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.[11][pageneeded] They have large canine teeth, and also high-crowned cheek teeth similar to those of ungulates.[12] Their dental formula is 1-3.1.4.23.1.4.2-3G
Although mostly diurnal[13] 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 the animal is disturbed, the pathway provides an obstacle-free escape route.
Elephant shrews are not highly social animals, but many live in monogamous pairs,and live in seldom. They share and defend their home territory if another organism were to trespass into their territory they would be violently kicked out, which involves screaming, sparring, snapping and kicking (Simmons, 1991). This territory is marked using scent glands.[12]Rhynchocyon species also dig small conical holes in the soil, bandicoot-style, but others may make use of natural crevices, or make leaf nests. and keep track of each other through scent marking.
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 within a few hours.[14]
Female elephant shrews undergo a menstrual cycle similar to that of human females and the species is one of the few nonprimate mammals to do so.[15] Elephant shrews were used in the 1940s to study the human menstruation cycle.[16] 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 bear 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.[12]
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 their dependency on their mother. The young will then establish their own home ranges (about 1km2 (0.39sqmi)) and will become sexually active within 41–46 days.[17][18]
The thermal characteristics of elephant shrews with similar body size, habitat and distribution are very close in most of the classifications. They can maintain homeothermy in different ambient temperatures where most of the species regulate their body temperature at 35°C and neither become hyperthermic but they balance the heat offload by increasing the EWL (evaporative water loss).[19]
Feeding habits
Elephant shrews mainly eat 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 a challenge; an 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, especially new leaves, seeds, and small fruits.[17]
Evolution
A number of fossil species are known, all from Africa. They were separate from the similar-appearing order Leptictida. A considerable diversification of macroscelids occurred in the Paleogene period. Some, such as Myohyrax, were so similar to hyraxes that they were initially included with that group, while others, such as Mylomygale, were relatively rodent-like. These unusual forms all died out by the Pleistocene.[20] Although macroscelids were classified in the past with many groups, often on the basis of superficial characteristics, considerable morphological and molecular evidence places them within Afrotheria, at the base of Afroinsectivora.[21]
In terms of timing, the divergence between macroscelids and afrosoricidans is thought to have occurred roughly 57.5 million years (Ma) ago, in the late Paleocene, while the diversification of extant macroscelids apparently began when the Rhynchocyon lineage split off about 33 Ma ago, in the early Oligocene.[22]Elephantulus is considered to have separated from Macroscelidini later in the Oligocene, about 28.5 Ma ago.[22]
A tenrec is a mammal belonging to any species within the afrotherian family Tenrecidae, which is endemic to Madagascar. Tenrecs are a very diverse group; as a result of convergent evolution, some resemble hedgehogs, shrews, opossums, rats, and mice. They occupy aquatic, arboreal, terrestrial, and fossorial environments. Some of these species, including the greater hedgehog tenrec, can be found in the Madagascar dry deciduous forests. However, the speciation rate in this group has been higher in humid forests.
Afrotheria is a superorder of mammals, the living members of which belong to groups that are either currently living in Africa or of African origin: golden moles, elephant shrews, otter shrews, tenrecs, aardvarks, hyraxes, elephants, sea cows, and several extinct clades. Most groups of afrotheres share little or no superficial resemblance, and their similarities have only become known in recent times because of genetics and molecular studies. Many afrothere groups are found mostly or exclusively in Africa, reflecting the fact that Africa was an island continent from the Cretaceous until the early Miocene around 20 million years ago, when Afro-Arabia collided with Eurasia.
The black and rufous sengi, the black and rufous elephant shrew, or the Zanj elephant shrew is one of the 17 species of elephant shrew found only in Africa. It is native to the lowland montane and dense forests of Kenya and Tanzania. Like other members of the genus Rhynchocyon, it is a relatively large species, with adults averaging about 28 cm (11 in) in length and 450–700 g (16–25 oz) in weight.
The short-snouted elephant shrew or short-snouted sengi is a species of elephant shrew in the family Macroscelididae. It is found over a wide area of Africa. Its natural habitats are dry savanna and subtropical or tropical dry lowland grassland.
Elephantulus is a genus of elephant shrew in the family Macroscelididae. It contains the following species:
The Cape elephant shrew, also known as the Cape rock elephant-shrew or Cape rock sengi, is a species of elephant shrew in the family Macroscelididae. It is endemic to South Africa, although it is a relatively common animal. Its natural habitat is rocky areas. Elephant shrews are not closely related to other species of shrews and to rodents such as mice. E. edwardii has been observed to be a non-flying mammal pollinator of the pagoda lily. Elephant shrews are floral pollinators due to their largely insectivorous diet. Elephant-shrews are pollinators of Hyobanche atropurpurea. It uses its long slender tongue to feed on the pagoda lily's nectar while getting the lily's pollen on its long nose. E. edwardii is also a pollinator of Protea sulphurea.
The bushveld elephant shrew or bushveld sengi is a species of elephant shrew in the family Macroscelididae. It is found in Angola, Botswana, Namibia, and South Africa. Its natural habitats are subtropical or tropical dry shrubland and hot deserts.
The Somali elephant shrew or Somali sengi is a species of elephant shrew in the family Macroscelididae.
The North African elephant shrew or North African sengi is a species of elephant shrew in the family Macroscelididae. It is found in Algeria, Libya, Morocco, and Tunisia, and is the only extant afrotherian within its range. The species was formerly classified in the genus Elephantulus, but molecular evidence indicates that it is more closely related to Petrodromus than to other members of Elephantulus. It was moved to a new genus, Petrosaltator, in 2016. The split with Petrodromus likely occurred during the Miocene period.
The rufous elephant shrew, rufous sengi or East African long-eared elephant-shrew is a species of elephant shrew in the family Macroscelididae. Found in Ethiopia, Kenya, Somalia, South Sudan, Tanzania and Uganda, its natural habitats are dry savanna and subtropical or tropical dry shrubland.
The western rock elephant shrew or western rock sengi is a species of elephant shrew in the family Macroscelididae. It is found in Namibia, South Africa, and possibly Angola and Botswana. Its natural habitats are subtropical or tropical dry shrubland and rocky areas.
The round-eared elephant shrew or round-eared sengi, is a species of elephant shrew (sengi) in the family Macroscelididae. It is found in Botswana, Namibia, and South Africa. Its natural habitats are subtropical or tropical dry shrubland, and grassland, and hot deserts. They eat insects, shoots, and roots. Their gestation period is 56 days.
Macroscelides is a genus of small shrew-like animals, the round-eared sengis, found in western Namibia and in South Africa; they are members of the clade Afrotheria.
The Chequered sengi is a species of elephant shrew in the family Macroscelididae. The scientific name is Rhynchocyon cirnei.
Rhynchocyon is a genus of elephant shrew in the family Macroscelididae. Members of this genus are known colloquially as giant sengis. They are a ground-dwelling mammal, significantly larger than their relatives in the order Macroscelidea that live primarily in dense forests across eastern Africa. Habitats range from eastern Africa's coastal forests, Rift Valley highlands, and the Congo basin. The species is widely threatened, with two of four assessed by the International Union for Conservation of Nature's Red List of Threatened Species. Habitat fragmentation from the growth of human settlements and activities are the primary threats to their populations. The genus contains the following five species and several subspecies:
The Karoo rock elephant shrew or Karoo rock sengi is an elephant shrew in the genus Elephantulus. It is found in Northern Cape Province and Western Cape Province in South Africa.
Macroscelides flavicaudatus is a species of elephant shrew in the family Macroscelididae found in the central Namib desert and southern Namibia.
Galegeeska is a genus of elephant shrew in the family Macroscelididae.
↑ Martin Pickford; Brigitte Senut; Helke Mocke; Cécile Mourer-Chauviré; Jean-Claude Rage; Pierre Mein (2014). "Eocene aridity in southwestern Africa: timing of onset and biological consequences". Transactions of the Royal Society of South Africa. 69 (3): 139–144. doi:10.1080/0035919X.2014.933452. S2CID128423895.
↑ Agwanda B. R., Rovero F., Lawson L. P., Vernesi C., & Amin R. (2021), "A new subspecies of giant sengi (Macroscelidea: Rhynchocyon) from coastal Kenya", Zootaxa, 4948 (2): zootaxa.4948.2.5, doi:10.11646/zootaxa.4948.2.5, PMID33757027{{citation}}: CS1 maint: multiple names: authors list (link)
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