Cochran Frog vs Common Fat-tailed Mouse Opossum

Nymphargus cochranae compared with Thylamys pusillus

Key Differences

• Cochran Frog is Vulnerable while Common Fat-tailed Mouse Opossum is Least Concern.

Taxonomic Classification

Rank	Cochran Frog	Common Fat-tailed Mouse Opossum
Kingdom same	Animalia (Animals)	Animalia (Animals)
Phylum same	Chordata (Chordates)	Chordata (Chordates)
Class	Amphibia (Amphibians)	Mammalia (Mammals)
Order	Anura (Frogs & Toads)	Didelphimorphia (Didelphimorphia)
Family	Centrolenidae	Didelphidae
Genus	Nymphargus	Thylamys
Species	Nymphargus cochranae	Thylamys pusillus

Evolutionary Relationship

Cochran Frog and Common Fat-tailed Mouse Opossum share a common ancestor at the Phylum level: Chordata. (Chordates)

Conservation Status

Cochran Frog

VU — Vulnerable

Common Fat-tailed Mouse Opossum

LC — Least Concern

Physical Characteristics

Attribute	Cochran Frog	Common Fat-tailed Mouse Opossum
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Cochran Frog

Habitat

Typically found in freshwater habitats, moist forests, and wetlands.

Range

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

Common Fat-tailed Mouse Opossum

Habitat

Typically found in diverse terrestrial and aquatic ecosystems.

Cochran Frog

The Cochran frog (Nymphargus cochranae) is a small glass frog in the family Centrolenidae, native to the cloud forests of the western and central Andes in Colombia. Like other centrolenid frogs, it is characterised by semi-transparent or translucent ventral skin through which internal organs — including the heart, liver, and digestive tract — are visible, a feature that gives the family its common name. The species inhabits humid montane rainforest along streams at elevations typically between 1,500 and 2,800 metres, where males call from vegetation overhanging fast-flowing streams to attract females. Eggs are deposited in gelatinous masses on leaves or rocks above the water; upon hatching, tadpoles drop into the stream below and develop in the current-swept environment. Nymphargus cochranae is classified as Vulnerable by the IUCN, primarily due to ongoing deforestation and degradation of cloud forest habitats driven by agricultural expansion, cattle ranching, and coca cultivation across its Colombian Andean range. Glass frogs are additionally sensitive to stream water quality, making them useful bioindicators of watershed health. The species was named in honour of the eminent American herpetologist Doris Mable Cochran of the Smithsonian Institution, who made foundational contributions to Central and South American amphibian taxonomy in the mid-twentieth century. Continued habitat protection and reforestation efforts are critical for its long-term survival.

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.