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Paradipus ctenodactyluscomb-toed jerboa

By Elle Glueckert

Geographic Range

The comb-toed jerboa, Paradipus ctenodactylus, occurs from southwestern Turkmenistan bordering the Caspian Sea northeast to the Syr Darya River in Kazakhstan (Corbet, 1978). The species is found specifically in the Kyzyl Kum desert of Uzbekistan and Kazakhstan and southern Kara Kum desert of Turkmenistan (Prakash and Ghosh, 1975). (Corbet, 1978; Prakash and Ghosh, 1975)

Habitat

Paradipus ctenodactylus is a psammophile found in the sandy Kyzyl Kum and Kara Kum deserts (Prakash and Ghosh, 1975). It is found concentrated in regions of these deserts with bushy vegetation such as sand acacia, calligonum, and tufts of three-awn. In these areas it is more common than any other rodent (Ognev, 1963). (Ognev, 1963; Prakash and Ghosh, 1975)

Physical Description

Comb-toed jerboas are similar to other jerboas. Like most jerboas, the eyes and ears are large, the tail is long, and the front limbs are short while the hind limbs are extremely elongated, lending themselves to the group's saltatorial mode of locomotion. The fur is a pinkish cinnamon to beige with white underparts and a broad white zone around each eye. There are rusty colored patches on the cheeks and chest and the tail has a large white tuft at the end (Nowak, 1991). (Nowak, 1991)

The length of the head and body is 110 to 155 mm and average weight is 140 g. The tail is not prehensile and is very long, approximately 206 to 221 mm (Nowak, 1991). Relative to other jerboas, the hind feet are very long at 73 to 82 mm (Ognev, 1963). These highly specialized hind limbs allow leaps of up to 3 m in length and 1 m in height and allow for surprising agility climbing shrubs as well. The three toes of the hind feet have a comb of stiff bristles with the longest bristles located on the medial toe and internal edges of the outer toes. These combed toes, from which the species' common name comes, are thought to assist in moving about the sandy habitat. Although the forelimbs are reduced, they are used for burrowing and have prominent claws, around 7 mm in length, which also assist in climbing and collecting food. The ears are longer than those of most other jerboas, at 33 to 38 mm (Nowak, 1991). Compared to other species in the subfamily Dipodinae, the cervical portion of the vertebral column is shorter, with complete fusion from vertebrae 2 to 6. Paradipus ctendactylus has white upper incisors, without the medial groove that is present in some jerboas. Premolars are absent (Ognev, 1963). (Nowak, 1991; Ognev, 1963)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    140 g
    4.93 oz
  • Range length
    110 to 155 mm
    4.33 to 6.10 in

Reproduction

Little is known about the reproductive habits of Paradipus ctenodactylus. A closely related species, Dipus sagitta, the rough legged jerboa, has been more closely studied. Dipus sagitta breeds in the same season as P. ctenodactylus and appears to have other similarities as well. During breeding season, D. sagitta males often fight over females. Males have been observed with multiple injuries and are occasionally even killed in these fights.

It has been suggested that the April-May period of breeding in both P. ctenodactylus and D. sagitta may include mostly older females, while the July period may also include yearling females (Prakash and Ghosh, 1975). Although D. sagitta has been observed breeding in its first year, at as early as 2 months of age, D. sagitta generally does not reproduce before one year of age. The gestation period is approximately 25 to 30 days. Litter size is around 2 to 5 young for D. sagitta. The young are born helpless and remain in the burrow for several months, until the middle of the summer to September (Ognev, 1963). (Ognev, 1963; Prakash and Ghosh, 1975)

  • Breeding interval
    Breeding intervals have not been well-studied in comb-toed jerboas.
  • Breeding season
    Breeding seems to occur in April and May and again in July.

Little is known about parental investment in comb-toed jerboas but, like other mammals, females care for and nourish their young at least through the age of weaning.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female

Lifespan/Longevity

Lifespan has not been recorded for P. ctenodactylus, but two other species of jerboa, Scirtopoda telum, the thick tailed three toed jerboa, and Allactaga sibirica, the jumper jerboa, have both been observed to live around 2 years in the wild. Only 3 to 7% lived to 3 years in both species (Prakash and Ghosh, 1975). (Prakash and Ghosh, 1975)

Behavior

Comb-toed jerboas are nocturnal. Days are spent in their burrows, usually dug at the base of the windward side of a barkhan dune. While most jerboas dig an emergency exit and seal their burrows off, P. ctenodactylus does not. Only one exit is present. When threatened in the burrow comb-toed jerboas dig new exits to escape (Ognev, 1963). Although they dig burrows in somewhat damp or compacted sand, the burrow is extremely difficult to open because of the layers of dry sand on top of the barkhan sliding down into the tunnel. It is not known whether comb-toed jerboas dig permanent burrows; it appears that they may not based on the large number of freshly dug burrows each morning. The burrow is generally 25 to 65 cm in length and ends in a nest chamber. Compared to the burrows of other jerboas, this is relatively simple, with no branches, a small nest chamber, and an unsealed exit. (Ognev, 1963; Prakash and Ghosh, 1975)

Paradipus ctenodactylus is extremely hard to observe. Thus many inferences have been made by analyzing tracks. Paradipus ctenodactylus has very distinctive tracks, which can be distinguished from the tracks of other types of jerboas. Their tracks are large because of the unusually large feet and have characteristic contours on the edges. Their tracks also tend to lie alternatively in a symmetric bipedal pattern, rather than in twos like some jerboas. Paradipus ctenodactylus appears to "play" in the sand, leaving rolling body marks as well as broad trampled stretches (Ognev, 1963). (Ognev, 1963)

From December to February, comb-toed jerboas hibernate. When the ground temperature drops to 16-18 degrees Celsius, hibernation begins. Hibernation appears to coincide with the dying of the fruits and the growing of the shoots of the white saxaul tree, which they feed on (Ognev, 1963). The burrows dug for hibernation are deeper than normal burrows and have a small amount of course bedding in the nest chamber. (Ognev, 1963)

  • Average territory size
    10 km^2

Home Range

Individuals make nightly rounds of their territories, which are 1.5 to 2 km in radius. This results in them traveling 7 to 11 km per night, sometimes even more, depending on the distance from their burrow to foraging areas (Ognev, 1991). Territories for individuals overlap considerably and during the summer in particular, territories may be shifted a number of times (Prakash and Ghosh, 1975). (Nowak, 1991; Ognev, 1963; Prakash and Ghosh, 1975)

Communication and Perception

Little is known about methods of communication. A similar species, Dipus sagitta, however, has been noted to make whinnying or moaning noises. Jerboas have excellent hearing and sight. Like other rodents, they also have a keen sense of smell and probably use olfactory cues extensively in communication (Ognev, 1963). (Ognev, 1963)

Food Habits

Comb-toed jerboas are completely herbivorous, eating only desert shrubs. Although they eat a variety of plant parts and species, they are highly discriminatory with respect to plant species eaten and are selective as to which parts they eat (Ognev, 1963). Individual differences as well as seasonal and locality differences in food preferences have been noted (Prakash and Ghosh, 1975). Identified foods include shoots of Salsola richteri, Haloxylon persicum, and Calligonum arborescens, flowers and leaves of Calligonum caputmedusae, Calligonum arborscens, Ammodendrum conollyi, Astragalus paucijugus, Artemesia ereocarpa, and Acanthophyllum borszewi, the seeds or ovaries of Ammodendrum conollyi, Aristida karelini, Horaninovia ulicina, Malcolmia bungei, Corispermum papillosum, Euphorbia heirolepis, and the fruit of << Haloxylon persicum>> and Peganum harmala (Ognev, 1963; Prakash and Ghosh, 1975). (Ognev, 1963; Prakash and Ghosh, 1975)

Their remarkable ability to climb shrubs using their forelimbs and teeth, use their hind legs to leap high into shrubs, and their balance allows this species to find and obtain food in desert shrubs and trees. Once the food is obtained, rather than being dragged back to the burrow, the food is dragged to an open area at the top of a sand dune to be eaten (Shenbrot et al., 1999). (Ognev, 1963; Prakash and Ghosh, 1975; Shenbrot, et al., 1999)

  • Plant Foods
  • leaves
  • wood, bark, or stems
  • seeds, grains, and nuts
  • flowers

Predation

Little is known about the interactions of Paradipus ctenodactylus with other species, as it is hard to observe P. ctenodactylus in the wild. When threatened, however, comb-toed jerboas make short dashes to escape. They are the fastest of any jerboa species, reaching speeds up to 180 m per minute, but they tire quickly. When disturbed in their burrows, these animals respond by digging deeper into the sand, since they do not construct emergency exits (Ognev, 1963). Other jerboas are known to be prey to foxes, ermines, owls, cats, and steppe polecats (Ognev, 1963). (Ognev, 1963)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

As it is very difficult to observe in the wild, little is known about the role of Paradipus ctenodactylus in the ecosystem. They may influence vegetation communities through their feeding habits and probably provide an important prey base for their predators. There are a number of flea species known to parasitize comb-toed jerboas. (Ognev, 1963)

Commensal/Parasitic Species
  • fleas Opthalmopsylla kasakiensis
  • fleas O. volgensis,
  • fleas Mesopsylla lenis
  • fleas M. tuschkan
  • fleas Xenopsylla mycerina
  • fleas Ceratophylus laeviceps

Economic Importance for Humans: Positive

Paradipus ctenodactylus has no known economic value to humans, aside from their role as members of healthy, native desert ecosystems.

Economic Importance for Humans: Negative

There are no known adverse effects of comb-toed jerboas on humans. Possible adverse effects of other jerboas that might apply to this species are spread of plague (Yersinia pestis) when caught as pets and the gnawing of roots from plants sometimes used as a source of food by people. However, these adverse effects are generally considered insignificant even for other species of jerboas (Ognev, 1963). (Ognev, 1963)

Conservation Status

Comb-toed jerboas are considered a species of lower risk/least concern by the IUCN Red List of Threatened Species.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Elle Glueckert (author), Michigan State University, Barbara Lundrigan (editor, instructor), Michigan State University.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Corbet, G. 1978. The Mammals of the Palaearctic Region. Ithaca, New York: Cornell University Press.

Nowak, R. 1991. Walker's Mammals of the World. Baltimore: Johns Hopkins University Press.

Ognev, S. 1963. Mammals of Eastern Europe and Northern Asia. Jerusalem: S. Moson.

Prakash, I., P. Ghosh. 1975. Rodents in Desert Environments. Netherlands: The Hague.

Shenbrot, G., B. Krasnov, K. Rogovin. 1999. Spatial Ecology of Desert Rodent Communities. Berlin: Springer.

Wilson, D., D. Reeder. 2005. Mammal Species of the World. Baltimore, MD: Johns Hopkins University Press.

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