The Argentine swamp rat (''Scapteromys aquaticus'') is a

semiaquatic In biology, being semi-aquatic refers to various macroorganisms that live regularly in both aquatic and terrestrial environments. When referring to animals, the term describes those that actively spend part of their daily time in water (in ...

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 ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

from

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. It is found in northeastern

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

and

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

, where it lives in freshwater marshes and along the southern coast of the

Río de la Plata The Río de la Plata (; ), also called the River Plate or La Plata River in English, is the estuary formed by the confluence of the Uruguay River and the Paraná River at Punta Gorda, Colonia, Punta Gorda. It empties into the Atlantic Ocean and ...

estuary, as well as in woodland. It is characterized by having stiff hairs on its otherwise naked tail, which are believed to help the animal

swim Swim or SWIM may refer to: Movement and sport * Swim, a fad dance * Aquatic locomotion, the act of biologically propelled motion through a liquid medium * Human swimming, the useful or recreational activity of movement through water * Swimming ( ...

. ''S. aquaticus'' is similar in build to members of the genus ''

Rattus ''Rattus'' is a genus of muroid rodents, all typically called rats. However, the term rat can also be applied to rodent species outside of this genus. Species and description The best-known ''Rattus'' species are the black rat (''R. rattus'') ...

''. " thas a relatively larger head, a stouter body, larger feet, and a relatively longer tail." The pelage along its back is "long and glossy" varying from brown to dark brown. It can have a grayish wash in some individuals. "The sides have a yellowish cast." The pelage in the abdominal region is typically an off white color. The forefeet are large for use in swimming and digging. All digits, including the pollex are equipped with a claw. Its

karyotype A karyotype is the general appearance of the complete set of chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is discerned by de ...

has 2n = 32.

Conservation

According to the IUCN Red List of Threatened Species in 2008 the Argentine swamp rat was classified as

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

because of "its wide distribution, presumed large

population Population is a set of humans or other organisms in a given region or area. Governments conduct a census to quantify the resident population size within a given jurisdiction. The term is also applied to non-human animals, microorganisms, and pl ...

, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a

threatened A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

category."

Habitat

These rodents are found in low, flooded grasslands, salt marshes and any area with standing water. They are good swimmers and employ the aid of their "swimming fringe" and have also been observed diving.

Distribution

Argentine swamp rats are found scattered through the Rio de la Plata basin and other areas in east-central Argentina, south coastal Brazil, southern Paraguay, and Uruguay.

Biology and behavior

Argentine swamp rats eat mostly

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

s and

earthworm An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...

s. They are active during both day and night.

Female An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and ...

s were found, on average, with between three and five young and breeding

male Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...

s were found year-round. There is no evidence that they dig

burrow file:Chipmunk-burrow (exits).jpg, An eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of Animal lo ...

s. Researchers have discovered young in shallow depressions in the ground covered by matted grass.

References

{{Taxonbar, from=Q1766652 Mammals of Argentina Scapteromys Mammals described in 1920 Taxa named by Oldfield Thomas