Common Fat-tailed Mouse Opossum vs Polar bear

Thylamys pusillus compared with Ursus maritimus

Key Differences

• Common Fat-tailed Mouse Opossum is Least Concern while Polar bear is Vulnerable.

Taxonomic Classification

Rank	Common Fat-tailed Mouse Opossum	Polar bear
Kingdom same	Animalia (动物界)	Animalia (动物界)
Phylum same	Chordata (脊索动物门)	Chordata (脊索动物门)
Class same	Mammalia (哺乳動物)	Mammalia (哺乳動物)
Order	Didelphimorphia (负鼠目)	Carnivora (食肉目)
Family	Didelphidae	Ursidae (Bears)
Genus	Thylamys	Ursus (Bears)
Species	Thylamys pusillus	Ursus maritimus

Evolutionary Relationship

Common Fat-tailed Mouse Opossum and Polar bear share a common ancestor at the Class level: Mammalia. (哺乳動物)

Conservation Status

Common Fat-tailed Mouse Opossum

LC — Least Concern

Polar bear

VU — Vulnerable

Population: ~26.0K

Trend: Decreasing ↓

Physical Characteristics

Attribute	Common Fat-tailed Mouse Opossum	Polar bear
Diet	—	Carnivore
Average Lifespan	—	25 years
Average Length	—	2.4 m
Average Weight	—	450.0 kg

Habitat & Geographic Range

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Polar bear

Habitat

Found across multiple habitat types including temperate broadleaf and mixed forests, temperate coniferous forests, and boreal forests and taiga, among 4 distinct biome types within the Palearctic biogeographic realm. Populations are also found in montane and highland environments at higher elevations.

Range

Found in Norway. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

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.

Polar bear

北极熊是地球上最大的陆地食肉动物，体重可超过700千克，分布于从加拿大到俄罗斯的北极海冰区。是高度特化的海洋哺乳动物，依赖海冰捕猎环斑海豹和髯海豹。是优秀的游泳者，能够横渡广阔的开阔水域。被列为易危种，因气候变化导致北极海冰迅速减少，种群正受到严重威胁。