Common Fat-tailed Mouse Opossum vs European water vole

Thylamys pusillus compared with Arvicola amphibius

Key Differences

• Common Fat-tailed Mouse Opossum is Least Concern while European water vole is Near Threatened.

Taxonomic Classification

Rank	Common Fat-tailed Mouse Opossum	European water vole
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class same	Mammalia (Mammals)	Mammalia (Mammals)
Order	Didelphimorphia (Didelphimorphia)	Rodentia (Rodents)
Family	Didelphidae	Cricetidae
Genus	Thylamys	Arvicola
Species	Thylamys pusillus	Arvicola amphibius

Evolutionary Relationship

Common Fat-tailed Mouse Opossum and European water vole share a common ancestor at the Class level: Mammalia. (Mammals)

Conservation Status

Common Fat-tailed Mouse Opossum

LC — Least Concern

European water vole

NT — Near Threatened

Physical Characteristics

Attribute	Common Fat-tailed Mouse Opossum	European water vole
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

European water vole

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Range

Distributed across Belgium, Denmark, Norway, Russia, and Sweden. Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Common Fat-tailed Mouse Opossum

The Common Fat-tailed Mouse Opossum (<em>Thylamys pusillus</em>) is a small marsupial belonging to the genus Thylamys within the family Didelphidae. Like other members of its genus, this species typically stores fat in its tail, which becomes swollen during periods of food abundance and is metabolised during leaner times, a physiological adaptation that provides energy reserves. <em>Thylamys pusillus</em> is generally found in diverse terrestrial and aquatic ecosystems, often in dry woodlands, scrublands, and grassland habitats of South America. The species is assessed as Least Concern on the IUCN Red List, indicating it is not currently considered at risk of extinction. Detailed geographic range data are not available in the current record, but members of this genus are typically distributed across parts of Argentina, Bolivia, Paraguay, and Uruguay. Biological traits including average lifespan, body dimensions, and specific dietary composition remain poorly documented in the scientific literature, though Thylamys species are generally considered omnivorous, often consuming insects, small vertebrates, and plant material.