Jerboa

Jerboa; Fossil range: Middle Miocene - Recent
	; Jaculus jaculus
Scientific classification
Kingdom:	Animalia;
Phylum:	Chordata;
Class:	Mammalia;
Order:	Rodentia;
Superfamily:	Dipodoidea;
Family:	Dipodidae; Fischer de Waldheim, 1817
Genera
	10 genera in 5 subfamilies

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The jerboa (from Arabic يربوع yarbū' or Hebrew יַרְבּוֹעַ yarbōa' ) form the bulk of the membership of the family Dipodidae. Jerboas are jumping desert rodents found throughout Asia and Northern Africa.

[edit] Characteristics

Lesser Egyptian Jerboa, Jaculus jaculus, skeletons mounted to show jump sequence, Muséum national d'histoire naturelle, Paris

Jerboas resemble mice with long tufted tails and very long hind legs. The small forelegs are not used for locomotion. In general, Asiatic jerboas have five toes on their hind feet and African jerboas have three; the shapes of their ears vary widely between species^{[citation needed]}. Jerboa fur is long, soft and silky. Diet varies considerably: some are specialist seed, insect, or plant eaters, others are omnivores^{[citation needed]}.

Jerboas have the ability to hop considerable distances relative to its size, an ability that evolved as an adaptation to help them escape from predators, and to assist with long journeys and foraging in its desert environment^{[citation needed]}. Although jerboas are not closely related to the hopping mice of Australia or the kangaroo rats of North America, all three groups have evolved a similar set of adaptations to life in the deep desert.^[1]

[edit] Burrows and Behavior

Jerboas are nocturnal. During the heat of the day, they shelter in burrows. They create four separate types of burrow: two temporary, and two permanent^{[citation needed]}. The temporary burrows are plain tubes used to escape predators during the night, tending to be just 10 to 20 cm (3.9 to 7.9 in) deep, unsealed and not camouflaged^{[citation needed]}. Permanent daytime burrows are well-hidden and sealed with a plug of sand to keep heat out and moisture in, and tend to be 20 to 50 cm (7.9 to 20 in) long^{[citation needed]}. A jerboa's permanent burrow often have multiple entrances, and are much more elaborate structures with a nesting chamber^{[citation needed]}. The winter burrows have food storage chambers 40 to 70 cm (16 to 28 in) below ground level, and a hibernation chamber an astonishing 1.5 to 2.5 m (4.9 to 8.2 ft) down.

Perhaps the best-known species is the Lesser Egyptian Jerboa (Jaculus jaculus) which occupies some of the most hostile deserts on the planet. It does not drink at all, relying on its food to provide enough moisture for survival^{[citation needed]}. Found in both the sandy and stony deserts of North Africa, Arabia and Iran, this small creature aestivates (analogous to hibernation) during the hottest summer months, and has the ability to leap a full metre to escape a predator^{[citation needed]}.

[edit] Possible Endangerment

Two species are considered threatened: the Five-toed Pygmy Jerboa (classed 'VU' vulnerable), the Thick-tailed Pygmy Jerboa (classed 'VU' vulnerable). A rare species only recently captured on film in the deserts of Mongolia and China, the Long-eared Jerboa (classed 'LC' least concern ^[2]) is no longer believed to be threatened. Many other species have been placed in a "lower risk" category, and one species (Thomas's Pygmy Jerboa) lacks the data for assessment.

[edit] Classification

Skeleton of a Jerboa

ORDER RODENTIA
Family Dipodidae
- Subfamily Zapodinae: jumping mice, 4 species in 3 genera
- Subfamily Sicistinae: birch mice
- Subfamily Cardiocraniinae
  - Cardiocranius
    - Five-toed Pygmy Jerboa, Cardiocranius paradoxus
  - Salpingotus
    - Thick-tailed Pygmy Jerboa, Salpingotus crassicauda
    - Heptner's Pygmy Jerboa, Salpingotus heptneri
    - Kozlov's Pygmy Jerboa, Salpingotus kozlovi
    - Baluchistan Pygmy Jerboa, Salpingotus michaelis
    - Pallid Pygmy Jerboa, Salpingotus pallidus
    - Thomas's Pygmy Jerboa, Salpingotus thomasi
- Subfamily Dipodinae
  - Dipus
    - Northern Three-toed Jerboa, Dipus sagitta
  - Eremodipus
    - Lichtenstein's Jerboa, Eremodipus lichensteini
  - Jaculus
    - Blanford's Jerboa, Jaculus blanfordi
    - Lesser Egyptian Jerboa, Jaculus jaculus
    - Greater Egyptian Jerboa, Jaculus orientalis
    - Turkmen Jerboa, Jaculus turcmenicus
  - Stylodipus
    - Andrews's Three-toed Jerboa, Stylodipus andrewsi
    - Mongolian Three-toed Jerboa, Stylodipus sungorus
    - Thick-tailed Three-toed Jerboa, Stylodipus telum
- Subfamily Euchoreutinae
  - Euchoreutes
    - Long-eared Jerboa, Euchoreutes naso
- Subfamily Allactaginae
  - Allactaga
    - Balikun Jerboa, Allactaga balikunica
    - Gobi Jerboa, Allactaga bullata
    - Small Five-toed Jerboa, Allactaga elater
    - Euphrates Jerboa, Allactaga euphratica
    - Iranian Jerboa, Allactaga firouzi
    - Hotson's Jerboa, Allactaga hotsoni
    - Great Jerboa, Allactaga major
    - Svertzov's Jerboa, Allactaga severtzovi
    - Mongolian Five-toed Jerboa, Allactaga sibirica
    - Four-toed Jerboa, Allactaga tetradactyla
    - Vinogradov's Jerboa, Allactaga vinogradovi
    - Bobrinski's Jerboa, Allactodipus bobrinskii
  - Pygeretmus
    - Lesser Fat-tailed Jerboa, Pygeretmus platyurus
    - Dwarf Fat-tailed Jerboa, Pygeretmus pumilo
    - Greater Fat-tailed Jerboa, Pygeretmus shitkovi
- Subfamily Paradipodinae
  - Paradipus
    - Comb-toed Jerboa, Paradipus ctenodactylus

[edit] References

^ "Convergent Evolution" in Heteromyidae
^ Batsaikhan, N., Avirmed, D., Tinnin, D. & Smith, A.T. (2008). Euchoreutes naso. 2008 IUCN Red List of Threatened Species. IUCN 2008. Retrieved on 26 May 2009. Database entry includes a brief justification of why this species is of least concern.