Diversity
Cricetomyinae, also known as pouched rats and mice, is an Old World group of nesomyid
rodents. This subfamily contains eight species in three genera (
Beamys
,
Cricetomys
, and
Saccostomus
), divided between two tribes.
Geographic Range
Habitat
Cricetomyines live in savannahs, agricultural fields, sandy plains, scrub forests,
moist woodlands, and forests. They are found at elevations from sea level to 2,100
meters.
- Terrestrial Biomes
- savanna or grassland
- forest
- scrub forest
- Other Habitat Features
- agricultural
Physical Description
Cricetomyines range in length from 98 mm to 450 mm, and their tails measure 30 to 450 mm. The length of the tail is less than or equal to the length of the body. Pouched rats weigh anywhere from 40 g to almost 3 kg. Male Cricetomys are larger than female Cricetomys , but sexual dimorphism has not been reported for the other genera. Cricetomyines have robust bodies with large heads and short limbs. These rodents get their common name from their large cheek pouches. The ears are rounded and may be short or very large and nearly naked. The thick tail is naked or covered with short hairs and the eyes are relatively small. The strong hind feet have short toes. The pelage may be long and dense or short, coarse, and sleek, and it is gray or brown on the dorsal surface of the animal and white, gray, or buff-colored below. The soles of the feet are hairless.
The
cricetomyine
dental formula is 1/1, 0/0, 0/0, 3/3 = 16. The upper
incisors
are ungrooved, and the
molars
are rooted and cuspidate. There are
accessory stylids
on the labial side of the lower molars and
accessory styles
on the lingual side of the upper molars. The chevron-shaped enamel ridges of the
molars are not joined by longitudinal
mures or murids
. There is a circular posteromedial cusp on the first and second lower molars. The
mandibular ramus
is relatively deep. The
rostrum
is long, and the area between the orbits is shaped like an hourglass. There is a
slight notch and spine formed from the
zygomatic plate
. The
jugal
is large and composes most of the
zygomatic arch
. The
malleus
is of parallel construction.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
- male larger
Reproduction
The mating system of cricetomyines has not been reported.
Some cricetomyines breed year round (e.g.,
Cricetomys
), and others breed only during the rainy season (e.g.
Beamys
). Litter sizes range from 1 (
Cricetomys gambianus
) to 10 (
Saccostomus campestris
). Gestation lasts from 22 to 32 days, the young open their eyes at about three weeks,
and they are weaned at five to six weeks. Young pouched rats reach sexual maturity
at seven to nine months.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Female cricetomyines build nests where they give birth to their young and nurse them
for five to six weeks.
- Parental Investment
- altricial
-
pre-fertilization
- provisioning
-
protecting
- female
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
The record longevity of a pouched rat in captivity is 7 years, 10 months. Cricetomyines
in the wild undoubtedly live much shorter lives.
Behavior
Cricetomyines are nocturnal rodents, only occasionally foraging during the day. They
are mainly terrestrial, but some climb and forage in trees and shrubs. On the ground,
they walk with a slow, ambling gait. They build nests out of dry vegetation and place
them in rock crevices, hollow trees, or in simple burrows situated among rocks. These
simple burrows range from one to nine meters in length and are about 60 cm below the
soil surface. Burrows contain chambers for storing food. Pouched rats have also
been known to make use of burrows constructed by other animals. Cricetomyines are
usually solitary, but males and females sometimes build their nests fairly close to
one another.
Communication and Perception
Cricetomyines communicate with one another through a range of complex vocalizations.
They rely most on their senses of smell and hearing, as their eyes are fairly small,
and if forced out into the daylight they behave as if nearly blind.
- Communication Channels
- acoustic
Food Habits
These rodents are herbivorous or omnivorous, eating fruit, seeds, nuts, berries, roots,
bulbs, crabs, snails, and sometimes insects. Coprophagy is known to occur in this
group. Pouched rats hoard food in their large cheek pouches and carry it back to
their burrows to store.
- Primary Diet
-
carnivore
- insectivore
- eats non-insect arthropods
- molluscivore
- herbivore
- omnivore
- coprophage
- Foraging Behavior
- stores or caches food
Predation
Small mammalian
carnivores
,
owls
, snakes and humans are the most important cricetomyine predators. These animals
probably rely on their vigilance, agility, and nocturnal habits to evade predation.
Ecosystem Roles
Cricetomyines have roles as primary and secondary consumers, and they are a food source
for other mammals. Because of their habit of storing seeds, it is likely that cricetomyines
also have a role in seed dispersal. Finally, cricetomyines are hosts for various
flea species, including
Xenopsylla crinita
,
Xenopsylla tortus
,
Xenopsylla sarodes
,
Dinopsyllus semnus
, as well as a parasitic earwig,
Hemimerus vosseleri
, and numerous
ticks
.
- Ecosystem Impact
- disperses seeds
Economic Importance for Humans: Positive
Some native tribes hunt and eat
Cricetomys gambianus
, and this species is sometimes kept as a pet by rodent enthusiasts.
Economic Importance for Humans: Negative
In some cities and towns,
Cricetomys gambianus
has become commensal with humans, living in sewers along with
Rattus
where it is also considered a pest. Also, cricetomyines carry the plague in some
areas.
- Negative Impacts
-
injures humans
- carries human disease
Conservation Status
The two
Beamys
species are currently listed as near threatened by the IUCN, due to human-induced
habitat loss and degradation.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
Allison Poor (author), University of Michigan-Ann Arbor.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- 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).
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- agricultural
-
living in landscapes dominated by human agriculture.
- 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.
- 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.
- 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).
- seasonal breeding
-
breeding is confined to a particular season
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- 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.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- food
-
A substance that provides both nutrients and energy to a living thing.
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- molluscivore
-
eats mollusks, members of Phylum Mollusca
- herbivore
-
An animal that eats mainly plants or parts of plants.
- frugivore
-
an animal that mainly eats fruit
- granivore
-
an animal that mainly eats seeds
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
- coprophage
-
an animal that mainly eats the dung of other animals
References
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Chaline, J., P. Mein, F. Petter. 1977. Les grandes lignes d'une classification évolutive des Muroidea. Mammalia , 41: 245-252.
Corti, M., R. Castiglia, F. Annesi, W. Verheyen. 2004. Mitochondrial sequences and karyotypes reveal hidden diversity in African pouched mice (subfamily Cricetomyinae, genus Saccostomus). Journal of Zoology , 262: 413–424.
Ellerman, J. 1941. The Families and Genera of Living Rodents, vol. II . London: British Museum (Natural History).
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IUCN, 2004. "2004 IUCN Red List of Threatened Species" (On-line). Accessed May 27, 2005 at www.redlist.org .
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Musser, G., M. Carleton. 2005. Superfamily Muroidea. Mammal Species of the World . Baltimore and London: The Johns Hopkins University Press.
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Petter, F. 1966. Affinités des genres Beamys, Saccostomus et Cricetomys (Rongeurs, Cricetomyinae). Annales du Musée Royal de l'Afrique Centrale, ser. 8 (Sciences Zoologiques) , 144: 13-25.
Roberts, A. 1951. The Mammals of South Africa . South Africa: Central News Agency.
Simpson, G. 1945. The principles of classification and a classification of mammals. Bulletin of the American Museum of Natural History , 85: 1-350.
Steppan, S., R. Adkins, J. Anderson. 2004. Phylogeny and divergence-date estimates of rapid radiations in muroid rodents based on multiple nuclear genes. Systematic Biology , 53(4): 533-553.
Thomas, O. 1896. On the genera of rodents: an attempt to bring up to date the current arrangement of the order. Proceedings of the Zoological Society of London : 1012-1028.