What is the correct name for a water rat? - briefly
The Australian water rat is scientifically named Hydromys chrysogaster and is commonly called the rakali. It is a murid rodent that lives in rivers, lakes and wetlands.
What is the correct name for a water rat? - in detail
The animal frequently referred to as a “water rat” is not a true rat. In Europe the species most often called by that name is the water vole (Arvicola amphibius), a semi‑aquatic member of the family Cricetidae. Its scientific designation distinguishes it from any Rattus species, which are true rats.
In Australasia the term applies to a different rodent, the Australian water rat (Hydromys chrysogaster). This mammal belongs to the family Muridae and exhibits adaptations for swimming, such as partially webbed hind feet and a dense, water‑repellent coat.
Key distinctions:
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Taxonomy
Arvicola amphibius – family Cricetidae, subfamily Arvicolinae.
Hydromys chrysogaster – family Muridae, subfamily Murinae. -
Geographic range
Europe and parts of western Asia for the water vole.
Eastern Australia and New Guinea for the Australian water rat. -
Morphology
Water vole: robust body, short tail, brownish fur, builds burrows near water.
Australian water rat: elongated body, long tail, partially webbed feet, dark brown to black fur. -
Behavior
Both are proficient swimmers; the water vole prefers shallow streams and ponds, while the Australian species inhabits fast‑flowing rivers and coastal streams.
Therefore, the precise term depends on the region: European references should use “water vole,” whereas Australasian contexts correctly employ “Australian water rat.” Both differ from true rats of the genus Rattus, which are primarily terrestrial.