Capped Orb Mussel vs Common Fat-tailed Mouse Opossum

Musculium lacustre compared with Thylamys pusillus

Taxonomic Classification

Rank	Capped Orb Mussel	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum	Mollusca (Mollusks)	Chordata (Chordates)
Class	Bivalvia (Bivalvia)	Mammalia (Mammals)
Order	Sphaeriida (Sphaeriida)	Didelphimorphia (Didelphimorphia)
Family	Sphaeriidae	Didelphidae
Genus	Musculium	Thylamys
Species	Musculium lacustre	Thylamys pusillus

Evolutionary Relationship

Capped Orb Mussel and Common Fat-tailed Mouse Opossum share a common ancestor at the Kingdom level: Animalia. (Animals)

Conservation Status

Capped Orb Mussel

LC — Least Concern

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Capped Orb Mussel	Common Fat-tailed Mouse Opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Capped Orb Mussel

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, Sweden, and United States.

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Capped Orb Mussel

The Capped Orb Mussel (Musculium lacustre) is a species in the genus Musculium. It is currently classified as Least Concern (LC) on the IUCN Red List. Native to Europe and North America, inhabiting ecosystems characteristic of the region.

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.