The chisel-toothed kangaroo rat (''Dipodomys microps'') is a species of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

in the family

Heteromyidae Heteromyidae is a family of rodents consisting of kangaroo rats, kangaroo mice, pocket mice and spiny pocket mice. Most heteromyids live in complex burrows within the deserts and grasslands of western North America, though species within the ...

. There are 13 sub-species.

Saltbush Saltbush is a vernacular plant name that most often refers to ''Atriplex'', a genus of about 250 plants distributed worldwide from subtropical to subarctic regions. ''Atriplex'' species are native to Australia, North and South America, and Eurasia. ...

leaves are a major dietary component, requiring specialized physiology to eliminate the salt while retaining water.

Description

They ranges between 268.4 - 273mm long with their body length from 100 - 116mm and tails being longer than their body ranges between 136 - 190mm. Their hind feet are approximately 40% the length of their body and ranges between 40 - 45mm and the front limbs being much shorter. Males tend to be a bit larger than the females. Their backs can range from a sandy brown, gray-brown to a pale yellow, their bellies are white, and their sides range from yellow to yellow gray. They have "tufted" tails which are brown with white stripes on the sided and the tuft at the end of the tail being dark brown with scattered white hairs. They have large rounded bicolour ears. Their incisors are unique and are used to identify them, they are anteriorly flattened and broad, like

chisel A chisel is a hand tool with a characteristic Wedge, wedge-shaped cutting edge on the end of its blade. A chisel is useful for carving or cutting a hard material such as woodworking, wood, lapidary, stone, or metalworking, metal. Using a chi ...

s, which is where their name comes from.

Geographic range and habitat

It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

(found in

Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...

Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

, and parts of

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

and

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

). They inhabit the arid regions with gravelly soils are found at moderate elevations (1000 - 1,500m), though they have been found at elevations of 3,200m above sea level. Their habit is saltbrush, especially ''Atriplex confertifolia'', dominated desert valleys and upland deserts with blackbush and are less common in sand dunes. They create burrows in the ground with multiple entries, usually under the bushes of shrubs. Their usual habitat is desert shrub.

Diet

''D. microps'' is a facultative specialist, and the only

foliovore In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds.Jones, S., Martin, R., & Pilbeam, D. (1 ...

in the ''

Dipodomys Kangaroo rats, small mostly nocturnal rodents of genus ''Dipodomys'', are native to arid areas of western North America. The common name derives from their bipedal form. They hop in a manner similar to the much larger kangaroo, but developed thi ...

'' genus. 60 - 80% of its diet consists of the ''

Atriplex confertifolia ''Atriplex confertifolia'', the shadscale or spiny saltbush, is a species of evergreen shrub in the family Amaranthaceae, which is native to the western United States and northern Mexico. Description The height of ''Atriplex confertifolia'' vari ...

's leaves.'' They do consume some seed and

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s, however, this is a small portion of their diet. This desert

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

, ''Atriplex confertifolia'', is adapted to desert life by encrusting its leaf surfaces with a layer of

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

crystals, this has a dual purpose, one of which is to reflect incoming solar radiation which help maintain its water

homeostasis In biology, homeostasis (British English, British also homoeostasis; ) is the state of steady internal physics, physical and chemistry, chemical conditions maintained by organism, living systems. This is the condition of optimal functioning fo ...

, and secondly it is a defense against

herbivory A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

. ''D. microps'' have adapted morphologically, physiologically, and behaviorally to overcome this

defense mechanism In psychoanalytic theory, defence mechanisms are unconscious psychological processes that protect the self from anxiety-producing thoughts and feelings related to internal conflicts and external stressors. According to this theory, healthy ...

. They have evolved their lower

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s to become flat, broad, and chisel-shaped, which is a unique to character among the kangaroo rats. They collect the

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

of the ''Atriplex'' shrub and stuff it into their

cheek pouch Cheek pouches are pockets on both sides of the head of some mammals between the jaw and the cheek. They can be found on mammals including the platypus, some rodents, and most monkeys, as well as the marsupial koala. The cheek pouches of chipmunk ...

and take it back to their burrows. They have been found to have caches of leaves of up 250g. Their unique incisors are used to scrape/strip the

epidermis The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermal layer provides a barrier to infection from environmental pathogens and regulates the ...

and the salt layer off of the leaf by repeatedly pulling the leaf downward and

perpendicular In geometry, two geometric objects are perpendicular if they intersect at right angles, i.e. at an angle of 90 degrees or π/2 radians. The condition of perpendicularity may be represented graphically using the '' perpendicular symbol'', � ...

to its lower incisors. This is then repeated on the other side till the inner tissue, consisting of the

parenchyma upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...

vascular tissue Vascular tissue is a complex transporting tissue, formed of more than one cell type, found in vascular plants. The primary components of vascular tissue are the xylem and phloem. These two tissues transport fluid and nutrients internally. T ...

bundle sheath A vascular bundle is a part of the transport system in vascular plants. The transport itself happens in the Plant stem, stem, which exists in two forms: xylem and phloem. Both these tissues are present in a vascular bundle, which in addition ...

, and the mesophyl, which is then consumed. This part of the leaf has a water content of up to 80% in the spring, and ''D. microps'' obtains its water from the leaves. Another

adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

to assist with the consumption is that the upper lip closes off the mouth cavity which reduces the amount of salt entering or falling into the mouth.

References

{{Taxonbar, from=Q1762619 Dipodomys Endemic rodents of the United States Fauna of the Western United States Fauna of the Great Basin Fauna of the Mojave Desert Fauna of the Sierra Nevada (United States) Natural history of the Transverse Ranges Mammals described in 1904 Least concern biota of the United States Taxa named by Clinton Hart Merriam Taxonomy articles created by Polbot