Elephant shrew

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Elephant shrew [1]
Temporal range: 48–0  Ma [2] [3]
Rhynchocyon petersi from side.jpg
Black and rufous elephant shrew, Rhynchocyon petersi, Philadelphia Zoo
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Placentalia
Superorder: Afrotheria
Grandorder: Afroinsectiphilia
Mirorder: Afroinsectivora
Order: Macroscelidea
Butler, 1956
Family: Macroscelididae
Bonaparte, 1838
Type genus
Macroscelides
A. Smith, 1829
Genera

Elephantulus
Galegeeska
Macroscelides
Petrodromus
Petrosaltator
Rhynchocyon

Contents

Elephant shrew range.jpg
Elephant shrew range genus.jpg
Range map of elephant shrew by genus

Elephant shrews, also called jumping shrews or sengis, are small insectivorous mammals native to Africa, belonging to the family Macroscelididae, in the order Macroscelidea. 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]

R. petersi skeleton, Museum of Osteology Black and Rufous Elephant Shrew skeleton.jpg
R. petersi skeleton, Museum of Osteology
Eastern rock elephant shrew, Elephantulus myurus, South Africa Eastern Rock Elephant Shrew.jpg
Eastern rock elephant shrew, Elephantulus myurus, South Africa
Bushveld elephant shrew, E. intufi, Namibia Bushveld-elephant-shrew.jpg
Bushveld elephant shrew, E. intufi, Namibia

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]

Description

Skeleton of North African elephant shrew. Macroscelidid skeleton.png
Skeleton of North African elephant shrew.

Elephant shrews are small, quadrupedal, insectivorous mammals. They have scaly tails, long snouts, and bear a superficial resemblance to shrews or rodents. They have long legs relative to their size, which are used to move from one place to another like rabbits. Elephant shrews use their flexible proboscises to search for food, with the length of the snout varying between species.

They are one of the fastest small mammals, having been recorded to reach speeds of 28.8 kilometres per hour (17.9 mph). [8] They vary in size from about 10 to 30 centimetres (3.9 to 11.8 in), from 50 to 500 grams (1.8 to 17.6 oz).[ citation needed ] One species of giant sengi, the grey-faced sengi, weighs about 700 g. Compared to other mammalian insectivores, sengis have relatively large brains. [9] Their lifespans are about two and a half to four years in the wild. [10] [ page needed ] They have large canine teeth, and also high-crowned cheek teeth similar to those of ungulates. [11] Their dental formula is 1-3.1.4.23.1.4.2-3G[ citation needed ]

Behavior and ecology

Although mostly diurnal [12] 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 solitary animals, despite many species living in monogamous pairs. They share and defend their home territory, which is marked using their scent glands. [11] Scent markings are also used for mate attraction. [13]

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, making it 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. [11]

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 1 km2 (0.39 sq mi)) 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. While awake, as much as 80% of their time may be spent foraging. [20] 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. [21] 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. [22]

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. [23] Elephantulus is considered to have separated from Macroscelidini later in the Oligocene, about 28.5 Ma ago. [23]

Phylogeny

Afrotheria
A cladogram of Afrotheria based on molecular evidence [22]
Cladogram of living elephant shrews [24] [23]
 Macroscelididae 

Classification

Round-eared elephant shrew, Macroscelides proboscideus, Basel Zoo Macroscelides proboscideus Basel Zoo 28102013.jpg
Round-eared elephant shrew, Macroscelides proboscideus, Basel Zoo
Four-toed sengi, Petrodromus tetradactylus, Mozambique Petrodromus tetradactylus-Zootaxa.jpg
Four-toed sengi, Petrodromus tetradactylus, Mozambique
North African elephant shrew, Petrosaltator rozeti, Morocco Petrosaltator rozeti-Zootaxa.jpg
North African elephant shrew, Petrosaltator rozeti, Morocco

The 20 species of elephant shrew are placed in six genera, three of which are monotypic:

Related Research Articles

<span class="mw-page-title-main">Afrotheria</span> Clade of mammals containing elephants and elephant shrews

Afrotheria is a superorder of placental 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.

<span class="mw-page-title-main">Black and rufous sengi</span> Species of mammal

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.

<span class="mw-page-title-main">Short-snouted elephant shrew</span> Species of mammal

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.

<i>Elephantulus</i> Genus of mammals

Elephantulus is a genus of elephant shrew in the family Macroscelididae. It contains the following species:

<span class="mw-page-title-main">Cape elephant shrew</span> Species of mammal

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 true shrews, nor 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.

<span class="mw-page-title-main">Bushveld elephant shrew</span> Species of mammal

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.

<span class="mw-page-title-main">Somali elephant shrew</span> Small animal of northeast Africa

The Somali elephant shrew or Somali sengi is a species of elephant shrew in the family Macroscelididae.

<span class="mw-page-title-main">North African elephant shrew</span> Species of mammal

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.

<span class="mw-page-title-main">Rufous elephant shrew</span> Species of mammal

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.

<span class="mw-page-title-main">Western rock elephant shrew</span> Species of mammal

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.

<i>Macroscelides proboscideus</i> Species of mammal

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.

<i>Macroscelides</i> Genus of mammals

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.

<span class="mw-page-title-main">Chequered sengi</span> Species of mammal

The chequered sengi is a species of elephant shrew in the family Macroscelididae. The scientific name is Rhynchocyon cirnei.

<i>Rhynchocyon</i> Genus of mammals

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:

<span class="mw-page-title-main">Karoo rock elephant shrew</span> Species of mammal

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.

<i>Macroscelides flavicaudatus</i> Species of mammal

Macroscelides flavicaudatus is a species of elephant shrew in the family Macroscelididae found in the central Namib desert and southern Namibia.

<i>Galegeeska</i> Genus of elephant shrew

Galegeeska is a genus of elephant shrew in the family Macroscelididae.

<span class="mw-page-title-main">Stuhlmann's sengi</span> Species of elephant shrew living in Africa

The Stuhlmann's sengi or white-tailed sengi is a species of elephant shrew that lives in the forests and savannas of Africa. It was discovered in 1893 and declared a new species. In the 1960s, however, it was downgraded to a subspecies of checkered sengi. In 2018, following genetic tests, scientists re-evaluated the mammal as a full species again.

References

  1. 1 2 Schlitter, D.A. (2005). "Order Macroscelidea". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 82–85. ISBN   978-0-8018-8221-0. OCLC   62265494.
  2. ↑ 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. S2CID   128423895.
  3. ↑ Martin Pickford (2015). "Chrysochloridae (Mammalia) from the Lutetian (Middle Eocene) of Black Crow, Namibia" (PDF). Communications of the Geological Survey of Namibia. 16: 105–113.
  4. ↑ Nishihara, Hidenori; Satta, Yoko; Nikaido, Masato; Thewissen, J. G. M.; Stanhope, Michael J.; Okada, Norihiro (2005). "A Retroposon Analysis of Afrotherian Phylogeny". Molecular Biology and Evolution. 22 (9): 1823–1833. doi: 10.1093/molbev/msi179 . PMID   15930154.
  5. ↑ Kingdon, J. (1997). The Kingdon Field Guide to African Mammals . London: Academic Press. ISBN   978-0-691-11692-1.
  6. ↑ Stanhope, M. J.; Waddell, V. G.; Madsen, O.; de Jong, W.; Hedges, S. B.; Cleven, G. C.; Kao, D.; Springer, M. S. (1998). "Molecular evidence for multiple origins of Insectivora and for a new order of endemic African insectivore mammals". Proceedings of the National Academy of Sciences. 95 (17): 9967–9972. Bibcode:1998PNAS...95.9967S. doi: 10.1073/pnas.95.17.9967 . PMC   21445 . PMID   9707584.
  7. ↑ Briggs, Helen (18 August 2020). "Elephant shrew rediscovered in Africa after 50 years". BBC News. Retrieved 19 August 2020.
  8. ↑ Davies, Ella (16 January 2014). "Secrets of the sengi: the world's fastest small mammal". BBC Nature. Archived from the original on 2014-01-16.
  9. ↑ Iwaniuk, A.; Kaufman, J.A.; Turner, G.H.; Holroyd, P.A.; Rovero, F.; Grossman, A. (2013). "Brain Volume of the Newly-Discovered Species Rhynchocyon udzungwensis (Mammalia: Afrotheria: Macroscelidea): Implications for Encephalization in Sengis". PLOS ONE. 8 (3): e58667. Bibcode:2013PLoSO...858667K. doi: 10.1371/journal.pone.0058667 . PMC   3596274 . PMID   23516530.
  10. ↑ Encyclopedia of Animals. Online database: EBSCO Publishing.
  11. 1 2 3 Rathbun, Galen B. (1984). Macdonald, D. (ed.). The Encyclopedia of Mammals . New York: Facts on File. pp.  730–733. ISBN   978-0-87196-871-5.
  12. ↑ Conniff, Richard. Shrewd Configuration, Smithsonian, June 2005. pp. 26-28.
  13. ↑ Rathbun, Galen B.; Woodall, Peter F. (March 2002). "A bibliography of elephant‐shrews or sengis (Macroscelidea)". Mammal Review. 32 (1): 66–70. doi:10.1046/j.1365-2907.2002.00092.x. ISSN   0305-1838.
  14. ↑ "Short-eared elephant-shrew (Macroscelides proboscideus) - A "living fossil" from the Namib-desert". Natur Spot. Archived from the original on 19 July 2011. Retrieved 1 February 2010.
  15. ↑ van der Horst, Cornelius; Gillman, Joseph (1941). "The menstrual cycle in Elephantulus". The South African Journal of Medical Sciences. 6: 27–47.
  16. ↑ Carter, A.M. (2018). "Classics revisited: C. J. Van der Horst on pregnancy and menstruation in elephant shrews". Placenta. 67: 24–30. doi:10.1016/j.placenta.2018.05.010. PMID   29941170. S2CID   49414099.
  17. 1 2 Rathbun, Galen B. (September 1992). "The Fairly True Elephant-Shrew". Natural History. 101. New York.
  18. ↑ Unger, Regina. "Short-eared Elephant-Shrews" . Retrieved 1 February 2010.
  19. ↑ Downs, Colleen T.; Perrin, M.R. (1995). "The thermal biology of three southern African elephant-shrews". Journal of Thermal Biology. 20 (6): 445–450. doi:10.1016/0306-4565(95)00003-F.
  20. ↑ Cooke, F.; Bruce, J. (2004). The Encyclopedia of Animals: A Complete Visual Guide. University of California Press. p. 243. ISBN   978-0-520-24406-1 . Retrieved 2 August 2024.
  21. ↑ Savage, RJG & Long, MR (1986). Mammal Evolution: an illustrated guide. New York: Facts on File. p.  54. ISBN   978-0-8160-1194-0.
  22. 1 2 Tabuce, R.; Asher, R. J.; Lehmann, T. (2008). "Afrotherian mammals: a review of current data" (PDF). Mammalia. 72: 2–14. doi:10.1515/MAMM.2008.004. S2CID   46133294. Archived from the original (PDF) on 2021-02-24. Retrieved 2020-08-15.
  23. 1 2 3 4 Heritage, S.; Rayaleh, H.; Awaleh, D.G.; Rathbun, G.B. (2020). "New records of a lost species and a geographic range expansion for sengis in the Horn of Africa". PeerJ. 8: e9652. doi: 10.7717/peerj.9652 . PMC   7441985 . PMID   32879790.
  24. ↑ Upham, Nathan S.; Esselstyn, Jacob A.; Jetz, Walter (2019). "Inferring the mammal tree: Species-level sets of phylogenies for questions in ecology, evolution and conservation". PLOS Biol. 17 (12): e3000494. doi: 10.1371/journal.pbio.3000494 . PMC   6892540 . PMID   31800571.
  25. ↑ Smit, H.A.; Robinson, T.J.; Watson, J.; Jansen Van Vuuren, B. (October 2008). "A new species of elephant-shrew (Afrotheria:Macroselidea: Elephantulus) from South Africa". Journal of Mammalogy. 89 (5): 1257–1269. doi: 10.1644/07-MAMM-A-254.1 .
  26. ↑ Krásová, Jarmila; Mikula, Ondřej; Šumbera, Radim; Horáková, Sylvie; Robovský, Jan; Kostin, Danila S.; Martynov, Aleksey A.; Lavrenchenko, Leonid A.; Bryja, Josef (2021). "The Rufous Sengi is not Elephantulus—Multilocus reconstruction of evolutionary history of sengis from the subfamily Macroscelidinae". Journal of Zoological Systematics and Evolutionary Research. 59 (4): 918–932. doi: 10.1111/jzs.12460 . ISSN   1439-0469. S2CID   233667864.
  27. ↑ 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, PMID   33757027 {{citation}}: CS1 maint: multiple names: authors list (link)
  28. ↑ Carlen, E.J.; Rathbun, G.B.; Olson, L.E.; Sabuni, C.A.; Stanley, W.T.; Dumbacher, J.P. (2017). "Reconstructing the molecular phylogeny of giant sengis (Macroscelidea; Macroscelididae; Rhynchocyon)". Molecular Phylogenetics and Evolution. 113: 150–160. doi: 10.1016/j.ympev.2017.05.012 . PMID   28552433.
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