Paradipus ctenodactylus

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).

• Biogeographic Regions
• palearctic palearctic
  • native native

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).

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune

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).

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).

• Other Physical Features
• endothermic endothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

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).

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

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 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).

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.

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).

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.

• Key Behaviors
• terricolous
• saltatorial saltatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• hibernation hibernation
• solitary solitary

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).

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).

• Communication Channels
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

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).

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).

• Primary Diet
• herbivore herbivore
  • folivore folivore

• 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).

• Anti-predator Adaptations
• cryptic 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.

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).

Conservation Status

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

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

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

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.