Meriones unguiculatus

Superregnum: Eukaryota
Cladus: Opisthokonta
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclassis: Tetrapoda
Classis: Mammalia
Subclassis: Theria
Infraclassis: Placentalia
Ordo: Rodentia
Subordo: Myomorpha
Superfamilia: Muroidea
Familia: Muridae
Subfamilia: Gerbillinae
Genus: Meriones
Species: Meriones unguiculatus

Meriones unguiculatus, the Mongolian Jird or Mongolian Gerbil is a rodent belonging to subfamily Gerbillinae. It is the most widely known species of the Gerbil subfamily, and is the usual gerbil species to be kept as a pet or experimental animal, when it is known as the Domesticated Gerbil. Like the Syrian Hamster (Golden Hamster), it was first brought to the United States in 1954 by Dr. Victor Schwentker for use in research. There were 44 pairs caught originally from Mongolia and brought to England. They were described as "squirrel colors... with long furry tails."

Origin

Meriones unguiculatus evolved on the semi-deserts and steppes of Mongolia. There, they developed long legs for jumping and running from predators, teeth to deal with hard seeds and plant matter, and water conservation techniques that allow them to survive in the arid climate, such as the ability to use dry food or stores of fat to generate metabolic water. Mongolian gerbils do not have many natural enemies due to the harsh climate. Most predators are birds-of-prey or snakes. Mongolian gerbils are diurnal, but return to their burrows for the coldest and hottest parts of the day.

Habitat

The species Meriones unguiculatus came originally from Mongolia. Its habitat in Mongolia is mainly semi-deserts and steppes. Soil on the steppes is sandy and is covered with grasses, herbs, and shrubs. The steppes have cool, dry winters and hot summers. The temperature can get up to 50 degrees Celsius (122 degrees Fahrenheit), but the average temperature for most of the year is around 20 °C (68 °F).

In the wild these gerbils live in groups generally consisting of one parental pair and the last few litters. Only the dominant female and male produce pups. One group of gerbils generally ranges over 325 to 1550 square meters (0.08 to 0.38 acre).

A group lives in a central burrow with 10-20 exits. Some deeper burrows with only 1-3 exits in their territory may exist. These deeper burrows are used to escape from predators when they are too far from the central burrow.

History

The first known mention of gerbils came in 1866, by Father Armand David, who sent "yellow rats" to the Museum of Natural History (Musée d'Histoire Naturelle) in Paris, from northern China. They were named Meriones unguiculatus by the scientist Milne-Edwards in 1867. This Latin name means "clawed warrior" in English, partly from the Greek warrior Meriones in Homer's Iliad.

Gerbils only became popular pets after 1954, when twenty breeding pairs of gerbils were brought to the United States from eastern Mongolia for scientific testing. Almost all pet gerbils today are descended from these forty. Gerbils were brought to the United Kingdom in 1964 from the United States.

Gerbils as Pets

Gerbils are rather popular pets, due to their gentle-towards-humans temperament and hardy nature.

Because the Mongolian Gerbil is a very social creature, it is recommended that they be kept in pairs in captivity; one reason being that multiple gerbils tend to groom each other, or engage in other social activities. Therefore, gerbils generally lead poorer lives without a companion. When selecting a gerbil as a pet, it is important to select healthy-looking animal. Important criteria include having clear eyes, ears and nostrils, a shiny coat, and a robust body shape. Gerbils that display their inquisitive nature are a better choice than ones that prefer hanging back in a corner. Gerbils of any age can be tamed so don't be put off if they're a a few months old, remember that all those cute pups will soon grow to be adults and their baby phase will quickly pass!

When choosing your pets, it is obviously important to know their genders. Most males of a rehomeable age have prominent testicles but some may be hidden, checking that the genital gap between the urethra and anus are the same on all gerbils is the best way to ensure that you aren't unwittingly getting opposite sexes!

A same sex pairing of gerbils from the same litter is the best choice. Placing a male and a female in an enclosure will lead to an inevitable population boom, one that may tax the abilities of even experienced owners.

Females can be somewhat more competitive with each other than males which is why pairs are more commonly encouraged. Most of the time, two gerbils will live together contentedly and will rarely have a dispute serious enough to warrant separation of the pair.

Attempting to introduce gerbils from different litters may be successful when done at a very early age. After reaching maturity however, it can be extremely difficult to get a gerbil to accept a new companion, even if they are siblings. A quarantine must always be used before introducing different gerbils to one another.

While a pair of gerbils is recommended, larger numbers can be housed together. A same sex pair requires a minimum of 10 gallons space, a trio should have a 20 gallon long tank. Groups of 4 can be successful but it is best to avoid them since the larger the group the better chance of future problems.

There are a number of options available when selecting an enclosure for gerbils. The most commonly seen are wire cages, vivariums, or tube-based habitats such as Habitrail. The best choice is usually a glass or acrylic aquarium tank, which allows a thick layer of substrate to be placed. This allows gerbils to burrow as they would naturally. An aquarium tank is also sturdy and safe, and helps alleviate problems such as drafts. A plastic enclosure will be easily chewed out of, and provides little ventilation.

Once an enclosure has been selected, the next step is to choose a substrate. Choices include commercially available small animal substrate, peat, kiln dried pine or Aspen wood shavings. Pine that is not kiln dried and cedar shavings must be avoided in the USA, since pine and cedar wood contain phenols that can cause respiratory problems in small animals. Ensure that the gerbils have sufficient bedding to dig through.

Gerbils will also appreciate a sand bath from time to time to keep their coats clean. Chinchilla sand is an option although aragonite sand is the best. Volcanic sand is another good option. Chinchilla dust is made for penetrating the chinchilla's thick fur and will just clog the lungs of gerbils and their owners from excessive inhalation! Sand bathing is very enjoyable for gerbils and it cleans the greases and oils in the coats. Not all gerbils will know how to bathe though, so rubbing the sand through their fur will have just as much benefit to keeping their fur clean.

Although the Mongolian Gerbil is a desert animal, they require fresh water at all times. Because of the gerbil’s active nature, it would be risky to place a dish or bowl of water in an enclosure as it would either be knocked over or filled with bedding which in turn would quickly turn it into a pool of unhealthy bacteria. Instead, use an easily accessible water bottle. Bottles that are custom made fit into many types of habitats or can be easily hung inside a glass tank with wire.

Food can be given through a relatively inexpensive dry food mix, many of which are easily found at grocery and pet stores, often labeled as “Hamster and Gerbil” food. Mixing in a seeded mix, such as wild bird food, is appreciated by the gerbils. Food bowls are not needed for gerbils but can be used if desired. A variety of gerbil, mouse and hamster mix can be offered, new foods do not need to be weaned into the main diet as gerbils thrive on a variety of food. When fresh vegetables or fruits are provided, be sure to clean out any uneaten portions after an hour or two.

Gerbil teeth, like the teeth of any rodent, grow constantly, so it is highly important to provide things for them to gnaw on. This wears the teeth down and keeps their growth in check. Wooden “toys” are offered at many pet stores for this purpose but there are many other house-hold things to offer gerbils too, such as the tube from a roll of paper towels, tissue boxes, etc. Wheels are something not all gerbils use, it is preferred to use a solid wheel to ensure legs or tails do not get caught in the wire.

Major Colors

* Golden Agouti — All Mongolian Gerbils in the wild are Golden Agouti, also called Agouti. The hair shafts on the back are grey at the base, gold in the middle and tipped with black, making an even mix of golden brown with black ticking. The belly is creamy white. An Agouti gerbil has black eyes.

* Black — A Black gerbil is black both on its back and on its belly. It most often has a "bib" or white line running down its chin. It also may have some white on its paws. A Black gerbil has black eyes.

* Argente — An Argente gerbil is orange with a white belly. It has deep ruby eyes. If one were to brush back the fur on its back, one would see that the roots are grey.

* Argente Cream — An Argente Cream gerbil is an Argente lightened by a Himalayan gene, c(h). It is light orange with a white belly and ruby eyes. The undercoat is grey like the Argente Gold, but diluted due to the c(h).

* Argente Fawn / Topaz — A Topaz gerbil is an Argente lightened by a gene called Chinchilla Medium, c(chm), formerly called Burmese, c(b). This color is lighter than an Argente Golden but darker than an Argente Cream, and it often has slightly darker points at the ears, nose and tail. It has ruby eyes. The undercoat is grey, but diluted due to the c(chm).

* Lilac — A Lilac gerbil is dark grey all over. It has ruby eyes.

* Dove — A Dove gerbil is a Lilac lightened by the Himalayan gene, c(h). It is a powdery light grey all over. It has ruby eyes.

* Sapphire — A Sapphire gerbil is a Lilac lightened by a gene called Chinchilla Medium, c(chm). This color is lighter than a Lilac but darker than a Dove. It has ruby eyes.

* Pink-eyed White — A Pink-eyed White gerbil is completely white with light ruby eyes.

* Burmese / Colourpoint Black — A Colourpoint black gerbil is an all over chocolate color. Around eight weeks or so, it will begin to develop darker points on the tail, nose, feet and tips of the ear. Often has a "bib" or white line running down the chin. It also may have some white on its paws. All Burmese gerbils have black eyes.

* Siamese / Light Colourpoint Black — A Siamese gerbil starts out a light mushroom color. Around eight weeks, it molts and the tail, nose, feet and tips of the ear go black. The main body color stays the same. A Siamese has black eyes. It also often has a "bib" or white line running down the chin. May also have some white on the paws.Younger Siamese gerbils can have lighter bands on their feet, but will fade on the back but may stay on the front. Their color is also described as "Musroom colorpoint".

* Colorpoint Agouti — A Colorpoint Agouti has an off-white to grey base with a liberal amount of silvery-brownish ticking along the back. The belly is white and the eyes are black.

* Light Colorpoint Agouti — A Light Colorpoint Agouti has an off-white base with silvery-brownish ticking along the back. Its belly is white and its eyes are black.

* Grey Agouti — The hairs on the back of a Grey Agouti are dark grey with white in the middle, making an even salt-and-pepper look. They often have gold intermingled into the coat. The belly is white. Grey Agoutis have black eyes.

* Slate — A Slate gerbil is a greyish black color. Often has a "bib" or white line running down the chin. It may also have some white on the paws. A Slate has black eyes with a reddish reflective shine in bright light or flash, however this can also appear on Black gerbils with certain recessives ie c(chm).

* Ivory Cream — An Ivory Cream gerbil is creamy colored on its back with a light cream belly. It has ruby eyes.

* Ruby-Eyed White — A Ruby-Eyed White gerbil is white all over. It has ruby eyes. Also known as Red Eyed White.

* Dark Eyed Honey — A Dark Eyed Honey gerbil starts out with a bright orange back with a white belly and flanks. At 8 weeks it molts and a small amount of black ticking appears along its back. A Dark Eyed Honey has black eyes.

* Nutmeg — A Nutmeg gerbil starts out with a bright orange color over its entire body. At 8 weeks it molts and liberal black ticking appears along the back with a lesser amount on the belly, changing the color from an orangey-brown to almost pure black, depending on the extensiveness of the ticking. A Nutmeg gerbil has black eyes.

* Silver Nutmeg — A Silver Nutmeg gerbil's first coat is an ivory color. At 8 weeks the gerbil molts and the liberal greyish ticking appears along the back with a lesser amount on the belly. A Silver Nutmeg gerbil has black eyes.

* Red Eyed Honey / Yellow Fox — A Yellow Fox gerbil has a bright orange back with a white belly and flanks. It has ruby eyes.

* Saffron / Red Fox — A Red Fox is a bright orange color over its entire body, with the color lightening somewhat through the belly area. Often there is a "bib" or white line running down the chin. There may also be some white on the paws. A Red Fox has ruby eyes.

* Polar Fox — A Polar Fox starts out a creamy ivory color. At 8 weeks the gerbil molts and minimal greyish ticking appears along the back. The nails are clear. A Polar Fox has black eyes.

* Schimmel — A Schimmel gerbil starts out as an orange color. At eight weeks old it molts and the coat begins to lighten to a creamy white. The gerbil's body continues to lighten throughout its life until it can be left with a white body, while the tail, nose, feet and tips of the ears retain the orange. Schimmel gerbils have black eyes. A schimmel with ruby eyes is a Ruby Eyed Schimmel.

* Black Eyed White — A Black Eyed White gerbil is completely white with black eyes. Some have greyish ear tips and dark claws.

* Spotting - Dominant spotting can be in any coat variety and will lighten the fur around it. How the spotting will look depends on modifiers.

* Collared - A thick, unbroken band of spotting around the neck connecting to the white belly.

* Collar and blaze - A thick, unbroken band of spotting around the neck connecting to the white belly and an unbroken white blaze connecting the three spotting areas (neck, forehead and nose).

* Pied - The base coat color may be of any standard type except for white. There is a thick band of white around the neck and shoulder area to form a collar that is connected to a blazed down the forehead and face. The distinguishing feature are small spots on the rump and back area around the spinal area. These spots usually do not have clear edges. The gerbil may be 50% white before it is considered a mottled gerbil as long as the spotting pattern conforms to the standard, accepted pattern.

* Mottled - The coat color of the gerbil may be any standard coat color broken by small white patches accompanying a collar and blaze. The gerbil may be up to 75% white until it would be considered a variegated gerbil.

* Variegated - The variegated pattern is when any standard coat color is broken up by small white patches along with a collar and blaze. The difference between the variegated spotting form and the mottled spotting form is the amount of white. The variegated spotting is an extended form of mottling. There is more white on the back and rump, allowing less color to show through. This can form a 'dalmatian' pattern. Often the tail tuft and the end of the tail is white or lacking pigment.

* Extreme White - The extreme white pattern is associated with any standard color except for white. Here the coat color is 90% white and barely any of the base coat color, or any pigment, is remaining. There have been health concerns circulating about extreme white gerbils. Head tilts, lack of good balance, and repetitive running and circling has been reported in these gerbils. It has been found that these health concerns mostly affect gerbils with unpigmented (light pink/not very opaque) ears.

There are other spotting "types". Any that don't conform to show standards are usually classed as patched.

These are just some examples of coat mutations. There are many more coat varieties in Mongolian gerbils.

Note: Although some US gerbil owners call some coat varieties "fox" ie yellow fox, the fox gene is not in gerbils and this is therefore incorrect.
References

* Baillie (1996). Meriones unguiculatus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006.
* History of the Mongolian gerbil - eGerbil.com
* Gerbil Coat Colour Reference Guides - eGerbil.com
* The Mongolian Gerbil in the Wild - eGerbil.com