Gerbil

Gerbil Fossil range: Late Miocene - Recent
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia Superfamily: Muroidea Family: Muridae Subfamily: Gerbillinae Gray, 1825
Genera
Ammodillus Brachiones Desmodilliscus Desmodillus Dipodillus Gerbilliscus Gerbillurus Gerbillus Meriones Microdillus Pachyuromys Psammomys Rhombomys Sekeetamys Tatera Taterillus

Gerbil is the common name for any of the small to medium-sized rodents in the Old World Muridae subfamily Gerbillinae, characterized by a mouse-like appearance, generally long tails and long, narrow hind feet, long claws, very thin enamel on the incisors, and 12 thoracic and 7 lumbar vertebrae. These terrestrial mammals, once known simply as desert rats, are adapted to arid conditions and are distributed throughout Africa, the Middle East, and central Asia, largely in dry habitats, including deserts. Some in this subfamily are also called by the common name of jird. There are over 100 species in 16 genera of gerbillines. As murids, gerbils are in the same family as true rats and mice.

In the wild, gerbils provide many values for the ecosystem. In food chains, gerbils consume nuts, seeds, fruits, grasses, insects, and bird eggs and are preyed upon by snakes, birds of prey such as owls, and small mammals. They also can play a role as pollinators of certain plants and likely in seed dispersal. Gerbillines, and in particular Meriones unguiculatus, the Mongolian gerbil, also provide a particular value to humans as a popular house pet and experimental animal, used for medical, psychological, and physiological research. Some species of gerbillines are considered major agricultural pests.

Overview and physical description

As rodents (order Rodentia), gerbils are characterized by dentition specialized for gnawing, with a single pair of upper incisors and single pair of lower incisors that grow continuously throughout their life and must be worn down by gnawing. The incisors have enamel on the outside and exposed dentine on the inside, so they self-sharpen during gnawing. Rodents lack canines and first premolars, which creates a space between their incisors and their grinding teeth (molars).

Within Rodentia, the gerbils belong to the superfamily Muroidea a vary large taxon that also includes hamsters, voles, true mice and rats, and many other relatives. They are the most populous group of rodents in the Northern Hemisphere and occupy a vast variety of habitats on every continent except Antarctica. They are often found in fossil occlusions of bones cached by past predators such as owls and other birds of prey.

Gerbls, along with true mice and rats, spiny mice, and the crested rat belong to the family Muridae. Murids are the largest family of mammals, containing over 700 species. Murids typically have slender bodies with scaled tails, and pointed snouts with prominent whiskers, but there is wide variation in these broad traits. The dental formula of murids is ${\tfrac {1.0.0.1-3}{1.0.0.1-3}}$.

Gerbils comprise the murid subfamily Gerbillinae, which is the most diverse of the murid subfamilies ((Dewey 2004). Gerbillines have 12 thoracic and 7 lumbar vertebrae and have very thin layers of enamel on the incisors compared to the other murids. The dental formula of gerbillines is ${\tfrac {1.0.0.3}{1.0.0.3}}$ = 16, with the ecceptoin of the genus Desmodilliscus, whose members only have two lower molars on each side. (Poor 2005).

Gerbils are small to medium-sized rodents, generally slender, and with tails making up about half of their total length. The body length of gerbils ranges from 50 to 200 millimeters (2 to 8 inches), while the tail lengths range from 56 to 245 millimeters (2.2 to 9.6 inches). The great gerbil, or Rhombomys opimus, originally native to Turkmenistan, can grow to more than 400 millimeters (16 inches) in total length. Weights of gerbils may range from 10 grams to 227 grams. They tend to have long, narrow hind feet and long claws. Ears may be long or short and fur also may be long or short, with the color of the pelage varying widely, including such colors as reddish, gray, olive, yellowish, dark brown, orangish and so forth (Poor 2005).

Gerbils have large eyes and good vision. They have enlarged hind limbs and most are saltatorial and capable of leaping a large distance (Poor 2005; Dewey 2004).

The word "gerbil" is a diminutive form of "jerboa", though the jerboas are an unrelated group of rodents occupying a similar ecological niche and somewhat similar appearance.

Distribution and habitat

Gerbils are terrestrial, Old World rodents, found widespread in [Africa]], the Middle East, and central Asia, including in much of India and in eastern Mongolia. Known once simply as "desert rats,' gerbils are adapted to extreme aridity, with adaptations such as producing concentrated urine and maintaining high relative humidity in their burrows (Dewey 2004). They often are found in dry, open habitats with sparse vegetation, such as deserts, steppes, mountain slopes, and grasslands, but some species also are found in moist woodlands, mountain valleys, and agricultural fields (Dewey 2004).

Behavior, life cycle, and reproduction

A young gerbil sitting by the food bowl to eat

Gerbils are terrestrial; some are good climbers. Depending on the species, gerbils may be diurnal, nocturnal, crespuscular, or active day and night. They build burrows for habitation, which can range from simple structures with a single entrance to elaborate networks of tunnels and multiple entrances and chambers, with different chambers for food storage, nesting, and excrement (Poor 2005).

Gerbils species may be solitary and territorial, with individuals occupying their own burrows; or live in small family groups with each family defending its territory; or gregarious and forming large colonies with many individuals living in extensive tunnel networks. Gerbillines nesting together tend to be very social in interaction, grooming and chasing one another. They utilize a range of vocalizations to communicate, from squeaks, to grunts, to a clicking noise, to drumming their hind feet. they also used chemical means to communicate (Poor 2005).

Individuals of most gerbil species have a life span of only three to four months in the wild, but in captivity some have lived up to eight years (Poor 2005). Gerbil species vary between those that breed year-round and those that breed seasonally. Litter sizes range from 1 to 13, with 4 to 7 common. Gerbils are born completely naked and blind and begin to grow fur about 1 to 2 weeks after birth and the eyes opening about 2 to 3 weeks after birth. Sexual maturity is reached between 10 and 16 weeks. Females have three to four pair of mammae. They brood and groom their young to about 1 month of age. Gerbil mothers have been noted to consume the urine and feces of the young. In some species, males care for and groom the young similar to the females (Poor 2005).

Diet and predation

Gerbils are primarily omnivorous or herbivorous. Their diet includes seeds, nuts, roots, fruits, grasses, insects, bulbs, and bird eggs, among other items. Some store large amounts of plant matter in their burrows, including up to 60 kilograms (Poor 2005).

Among predators of gerbils are snakes, birds of prey such as owls, and small mammals. Some utilize camouflage for protection or block their burrow entrances (Poor 2005).

Classification

The gerbil subfamily includes about 110 species in 16 genera.

SUBFAMILY GERBILLINAE

• Tribe Ammodillini
  • Genus Ammodillus
    • Ammodile, Ammodillus imbellis
• Tribe Desmodilliscini
  • Genus Desmodilliscus
    • Pouched gerbil, Desmodilliscus braueri
  • Genus Pachyuromys
    • Fat-tailed gerbil, Pachyuromys duprasi
• Tribe Gerbillini
  • Subtribe Gerbillina
    • Genus Dipodillus
      • Botta's gerbil, Dipodillus bottai
      • North African gerbil, Dipodillus campestris
      • Wagner's gerbil, Dipodillus dasyurus
      • Harwood's gerbil, Dipodillus harwoodi
      • James's gerbil, Dipodillus jamesi
      • Lowe's gerbil, Dipodillus lowei
      • Mackilligin's gerbil, Dipodillus mackilligini
      • Greater short-tailed gerbil, Dipodillus maghrebi
      • Rupicolous gerbil, Dipodillus rupicola
      • Lesser short-tailed gerbil, Dipodillus simoni
      • Somalian gerbil, Dipodillus somalicus
      • Khartoum gerbil, Dipodillus stigmonyx
      • Kerkennah Islands gerbil, Dipodillus zakariai
    • Genus Gerbillus
      • Subgenus Hendecapleura
        • Pleasant gerbil, Gerbillus amoenus
        • Brockman's gerbil, Gerbillus brockmani
        • Black-tufted gerbil, Gerbillus famulus
        • Algerian gerbil, Gerbillus garamantis
        • Grobben's gerbil, Gerbillus grobbeni
        • Pygmy gerbil, Gerbillus henleyi
        • Mauritian gerbil, Gerbillus mauritaniae (sometimes considered a separate genus Monodia)
        • Harrison's gerbil, Gerbillus mesopotamiae
        • Barfur gerbil, Gerbillus muriculus
        • Balochistan gerbil, Gerbillus nanus
        • Large Aden gerbil, Gerbillus poecilops
        • Principal gerbil, Gerbillus principulus
        • Least gerbil, Gerbillus pusillus
        • Sand gerbil, Gerbillus syrticus
        • Vivacious gerbil, Gerbillus vivax (may be G. amoenus or G. nanus)
        • Waters's gerbil, Gerbillus watersi
      • Subgenus Gerbillus
        • Berbera gerbil, Gerbillus acticola
        • Agag gerbil, Gerbillus agag
        • Anderson's gerbil, Gerbillus andersoni
        • Swarthy gerbil, Gerbillus aquilus
        • Burton's gerbil, Gerbillus burtoni
        • Cheesman's gerbil, Gerbillus cheesmani
        • Dongola gerbil, Gerbillus dongolanus
        • Somalia gerbil, Gerbillus dunni
        • Flower's gerbil, Gerbillus floweri
        • Lesser gerbil, Gerbillus gerbillus
        • Indian hairy-footed gerbil, Gerbillus gleadowi
        • Western gerbil, Gergbillus hesperinus
        • Hoogstraal's gerbil, Gerbillus hoogstraali
        • Lataste's gerbil, Gerbillus latastei
        • Sudan gerbil, Gerbillus nancillus
        • Nigerian gerbil, Gerbillus nigeriae
        • Occidental gerbil, Gerbillus occiduus
        • Pale gerbil, Gerbillus perpallidus
        • Cushioned gerbil, Gerbillus pulvinatus
        • Greater Egyptian gerbil, Gerbillus pyramidum
        • Rosalinda gerbil, Gerbillus rosalinda
        • Tarabul's gerbil, Gerbillus tarabuli
    • Genus Microdillus
      • Somali Pygmy Gerbil, Microdillus peeli
  • Subtribe Rhombomyina
    • Genus Brachiones
      • Przewalski's gerbil, Brachiones przewalskii
    • Genus Meriones
      • Subgenus Meriones
        • Tamarisk jird, Meriones tamariscinus
      • Subgenus Parameriones
        • Persian jird, Meriones persicus
        • King jird, Meriones rex
      • Subgenus Pallasiomys
        • Arabian jird, Meriones arimalius
        • Cheng's jird, Meriones chengi
        • Sundevall's jird, Meriones crassus
        • Dahl's jird, Meriones dahli
        • Moroccan jird, Meriones grandis
        • Libyan jird, Meriones libycus
        • Midday jird, Meriones meridianus
        • Buxton's jird, Meriones sacramenti
        • Shaw's jird, Meriones shawi
        • Tristram's jird, Meriones tristrami
        • Mongolian jird (Mongolian Gerbil), Meriones unguiculatus
        • Vinogradov's jird, Meriones vinogradovi
        • Zarudny's jird, Meriones zarudnyi
      • Subgenus Cheliones
        • Indian desert jird, Meriones hurrianae
    • Genus Psammomys
      • Sand rat, Psammomys obesus
      • Thin sand rat, Psammomys vexillaris
    • Genus Rhombomys
      • Great gerbil, Rhombomys opimus
  • incertae sedis
    • Genus Sekeetamys
      • Bushy-tailed jird, Sekeetamys calurus
• Tribe Gerbillurini
  • Genus Desmodillus
    • Cape short-eared gerbil, Desmodillus auricularis
  • Genus Gerbilliscus
    • Cape gerbil, Gerbilliscus afra
    • Boehm's gerbil, Gerbilliscus boehmi
    • Highveld gerbil, Gerbilliscus brantsii
    • Guinean gerbil, Gerbilliscus guineae
    • Gorongoza gerbil, Gerbilliscus inclusus
    • Kemp's gerbil, Gerbilliscus kempi
    • Bushveld gerbil, Gerbilliscus leucogaster
    • Black-tailed gerbil, Gerbilliscus nigricaudus
    • Phillips's gerbil, Gerbilliscus phillipsi
    • Fringe-tailed gerbil, Gerbilliscus robustus
    • Savanna gerbil, Gerbilliscus validus
  • Genus Gerbillurus
    • Hairy-footed gerbil, Gerbillurus paeba
    • Namib brush-tailed gerbil, Gerbillurus setzeri
    • Dune hairy-footed gerbil, Gerbillurus tytonis
    • Bushy-tailed hairy-footed gerbil, Gerbillurus vallinus
  • Genus Tatera
    • Indian gerbil, Tatera indica
• Tribe Taterillini
  • Genus Taterillus
    • Robbins's tateril, Taterillus arenarius
    • Congo gerbil, Taterillus congicus
    • Emin's gerbil, Taterillus emini
    • Gracile tateril, Taterillus gracilis
    • Harrington's gerbil, Taterillus harringtoni
    • Lake Chad gerbil, Taterillus lacustris
    • Petter's gerbil, Taterillus petteri
    • Senegal gerbil, Taterillus pygargus
    • Tranieri's tateril, Taterillus tranieri

Gerbils as pets

Gerbils were first introduced to the pet industry in 1964. These were the Mongolian gerbils. Their value as pets was soon appreciated and they are now found in pet shops all over the UK and USA. Due to the threat they pose to indigenous ecosystems and existing agricultural operations, it is illegal to purchase, import, or keep a gerbil as a pet in the US state of California.

One Mongolian species, Meriones unguiculatus, also known as the clawed jird, is a gentle and hardy animal that has become a popular pet. It was first brought from China to Paris, France in the 19th century, and became a popular house pet. It was then brought to the United States in 1954 by Dr. Victor Schwentker for use in research.

Housing in captivity

A common misunderstanding when purchasing a home for pet gerbils is they can live in housing designed for hamsters and mice. This is not correct, as they need to be able to dig tunnel systems, rather than have them created for them. The commonly plastic structure of hamster and mouse cages is inappropriate for gerbils due to their ability to gnaw through it very quickly. Plastic can cause serious health issues for the animal if ingested, therefore many owners refrain from having any plastic in the tank and rely entirely on wooden toys. Information from gerbil societies from throughout the globe is conflicting with regards to tank sizing. However, a common minimum given appears to be 10 imperial gallons per gerbil.

Mating

Gerbils will mate for several hours, in frequent short bursts followed by short chases, when the female allows the male to catch her. Once he catches her, the female will squeak and make flick motions to get the male off her. Males will not attack females except in rare circumstances, which may also include them having been separated from their original mates, or widowed. A female may attack a male, but usually he is more than a match for her.

Reasons for popularity

The several reasons for the popularity of gerbils as household pets include: The animals are typically not aggressive, and they rarely bite unprovoked or without stress. They are small and easy to handle, since they are sociable creatures that enjoy the company of humans and other gerbils. Gerbils also have adapted their kidneys to produce a minimum of waste to conserve body fluids, which makes them very clean with little odor.

Health concerns

Teeth problems

Misalignment of incisors due to injury or malnutrition may result in overgrowth, which can cause injury to the roof of the mouth. Symptoms include a dropped or loss of appetite, drooling, weight loss, or foul breath. The teeth must be clipped by a veterinarian regularly for as long as required.

Trauma

Common injuries are caused by gerbils being dropped or falling, often while inside of a hamster ball, which can cause broken limbs or a fractured spine (for which there is no cure).

Neglect

A common problem for all small rodents is neglect, which can cause the gerbils to not receive adequate food and water, causing serious health concerns, including dehydration, starvation, stomach ulcers, eating of bedding material, and cannibalism.

Epilepsy

Between 20 and 50% of all pet gerbils have the seizure disorder epilepsy. The seizures are thought to be caused by fright, handling, or a new environment. The attacks can be mild to severe, but do not typically appear to have any long-term effects, except for rare cases where death results from very severe seizures. A way to avoid a gerbil having a seizure is to refrain from blowing in the animal's face (often used to "train" the pet not to bite), this is used in a lab environment to induce seizures for medical research.

Tumors

Tumors, both benign and malignant, are fairly common in pet gerbils, and are most common in females over the age of two. Usually, the tumors involve the ovaries, causing an extended abdomen, or the skin, with tumors most often developing around the ears, feet, midabdomen, and base of the tail, appearing as a lump or abscess. The scent gland (positioned on the abdomen) should be checked regularly; a veterinarian can operate on the lump where possible.

Tail sloughing

Gerbils can lose their tails due to improper handling, being attacked by another animal, or getting their tails stuck. The first sign is a loss of fur from the tip of the tail, then, the skinless tail dies off and sloughs, with the stump usually healing without complications.

Tyzzer's disease

The most common infectious disease in gerbils is Tyzzer's disease, which is often caused by either stress or bacteria, and produces symptoms such as ruffled fur, lethargy, hunched posture, poor appetite, diarrhoea, and often death. It quickly spreads between gerbils in close contact.

Deafness and inner ear problems

A problem with the inner ear can be spotted by a gerbil leaning to one side quite obviously. The fluids in the ears affect balance. However, this does not appear to affect the gerbils too much, which have an aptitude of just getting on with things, and getting used to their conditions. Gerbils with "extreme white spotting" colouring are susceptible to deafness; this is thought to be due to the lack of pigmentation in and around the ear.

Captive-bred gerbils

File:Burmese colored gerbil.jpg

A Burmese colored gerbil

A male and female fat-tailed gerbil (Pachyuromys duprasi)

Many color varieties of gerbils are available in pet shops today, generally the result of years of selective breeding.

Over 20 different coat colors occur in the Mongolian gerbil, which has been captive-bred the longest.

Another species of gerbil has also been recently introduced to the pet industry: the fat-tailed gerbil, or duprasi. They are smaller than the common Mongolian gerbils, and have long, soft coats and short, fat tails, appearing more like a hamster. The variation on the normal duprasi coat is more gray in color, which may be a mutation, or it may be the result of hybrids between the Egyptian and Algerian subspecies of duprasi.

White spotting has been reported in not only the Mongolian gerbil, but also the pallid gerbil and possibly Sundervall's Jird.

A long-haired mutation, a grey agouti or chinchilla mutation, white spotting, and possibly a dilute mutation have also appeared in Shaw's jirds, and white spotting and a dilute mutation have shown up in Bushy-tailed Jirds.

See also

• Jird
• Jerboa
• Indian desert jird

References

ISBN links support NWE through referral fees

Resources

• McKenna, M. C. and S. K. Bell. 1997. Classification of Mammals above the Species Level. Columbia University Press, New York.
• Musser, G. G. and M. D. Carleton. 1993. Family Muridae. Pp. 501–755 in Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Smithsonian Institution Press, Washington D.C.
• Nowak, R. M. 1999. Walker's Mammals of the World, Vol. 2. Johns Hopkins University Press, London.
• Pavlinov, I. Ya., Yu. A. Dubrovskiy, O. L. Rossolimo, E. G. Potapova. 1990. Gerbils of the world. Nauka, Moscow.
• http://www.research.usf.edu/cm/CMDC/C111_Normative_Biology_Diseases_Gerbils_7_03.pdf

• Dewey, T.A. 2004. Rats, mice, and relatives V. Pages 281-298 in B. Grzimek et al., Grzimek's Animal Life Encyclopedia, 2nd edition, vol. 16, mammals V. Detroit, MI: Thomson/Gale, 2004. ISBN 0787657921.

• Poor, A. 2005. "Gerbillinae" (On-line), Animal Diversity Web. Accessed October 27, 2013 at http://animaldiversity.ummz.umich.edu/accounts/Gerbillinae/

External links

• The UK's National Gerbil Society
• The Gerbils.com - Everything about the gerbil
• eGerbil- For everything gerbil!
• American Gerbil Society

Template:Muridae Template:Gerbillinae

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