Dipodidae

The dipodids (Dipodidae) are a family of myomorphic rodents that inhabit the Northern Hemisphere. This family includes more than 50 extant species among 16 genera. These include gerbils and sicistas. The different species are found in grasslands, deserts, and forests. All of them are capable of long jumps (jumping while they are in a bipedal posture), a feature that is more evolved in desert gerbils.

Anatomy and body features

Dipodids are small to medium-sized rodents, ranging from 4 to 26 cm in length, excluding the tail. All of them are adapted to jump, although to different degrees. Gerbils have very long hind legs. They move well, hopping, or walking on their hind legs. Most dipods have long tails to aid their balance. Sicistas have shorter feet and tails, but they also move forward by hopping.

Jerbils resemble miniature kangaroos and have some external similarities. Both have long hind legs, short front legs, and a long tail. Gerbils move in a similar way to kangaroos, that is, jumping. However, upon closer inspection, their locomotion differs: In addition to speed, they make use of sharp turns and large vertical jumps to confuse and escape predators. Also, unlike kangaroos, the primary tendons of the hindlimbs only recover and reuse about 3.1-14.3% of the energy input into jumping, less than in many jumping animals.

Like other bipedal animals, its foramen magnum - the hole at the base of the skull - is displaced forward, which enhances two-legged locomotion. A gerbil's tail can be longer than its head and its body, and it is common to see a group of white hair at the end of the tail. Jerboas use their tails for balance when jumping and for support when sitting upright. The fur of the jerboas is fine and is usually the color of sand. This color often matches the jerboa's habitat (an example of cryptic coloration). Some species in the jerboa family have long ears like a rabbit, while others have short ears like a mouse or a snail. rat.

Natural history

Most are omnivorous, eating a diet consisting of seeds and insects. Some species, however, such as Allactaga sibirica, are almost exclusively insectivorous. Like other rodents, they have separated from the incisors.

Most make their nests in burrows, which, in the case of gerbils, can be complex, with chambers for food storage. Unlike mice, who sometimes choose to use the burrows of other species, and do not dig their own burrows, in addition to nesting in dense vegetation. Most species accumulate large amounts of fat before hibernating.

Dipodids can give birth to litters of between two and seven young after a gestation period of between 17 and 42 days. They reproduce once or twice a year, depending on the species.

Behavior

Bipedal locomotion of jerboas involves hopping, hopping, and running movements, associated with rapid and frequent changes in speed and direction, difficult to predict, that facilitate evasion from predators compared to quadrupedal locomotion. This may explain why the evolution of bipedal locomotion is favored in desert-dwelling rodents that forage for food in open habitats.

Gerbils are most active at twilight (crepuscular). During the heat of the day, they take refuge in burrows. At night, they come out of the burrows due to the cooler temperature of their environment. They dig their burrow entrances close to vegetation, especially at the edges of fields. During the rainy season, they tunnel into mounds or hills to reduce the risk of flooding. In summer, the jerboas that occupy the burrows plug the entrance to keep out hot air and, some researchers speculate, predators. In most cases, the burrows are built with an emergency exit ending just below. from the surface or opens at the surface but is not strongly obstructed. This allows the gerbil to quickly escape from predators.

Related gerbils typically create four types of burrows. A temporary, daytime burrow, used for cover while hunting during the day. They have a second, temporary burrow that they use to hunt at night. They also have two permanent burrows: one for summer and one for winter. The permanent summer burrow is actively used throughout the summer and the young are reared in it. Gerbils hibernate during the winter and use the permanent winter burrow for this. Temporary burrows are shorter than permanent ones. Like other hibernating animals, these creatures are heaviest before hibernation, specifically on non-grazed (Shuai) sites. In addition, increased food availability during prehibernation contributes to higher body mass of jerboas in non-grazed regions, and attracts more jerboas to migrate to non-grazed areas during posthibernation. Grazing negatively affects the jerboa population before and after hibernation, but not the survival rate.

Gerbils are solitary creatures. Once they reach adulthood, they often have their own burrow and forage for food on their own. However, 'loose colonies' may occasionally form, in which some species of jerboa dig communal burrows that offer additional warmth when it is cold outside.

Classification

• Dipodidae Family
  • Subfamily Sicistinae
    • Sicist
  • Subfamily Zapodinae
    • Eozapus
    • Napaeozapus
    • Zapus
  • Subfamily Allactaginae
    • Allactaga
    • Allactodipus
    • Pygeretmus
  • Subfamily Cardiocraniinae
    • Cardiocranius
    • Salpingotulus
    • Salpingotus
  • Subfamily Dipodinae
    • Dipus
    • Eremodipus
    • Jaculus
    • Paradipus
    • Stylodipus
  • Subfamily Euchoreutinae
    • Euchoreutes

In addition, the following extinct genera are known:

• †Brachyscirtetes Schaub, 1934
• †Heosminthus Wang, 1985
• †Heterosminthus Schaub, 1930
• †Lophocricetus Schlosser, 1924
• †Paralactaga Young, 1927
• †Parasminthus Bohlin, 1946
• †Proalactaga Savinov, 1970
• †Protalactaga Young, 1929
• †Sinozapus Qiu & Storch, 2000
• †Sminthoides Schlosser, 1924