Mammals
Water Opossum
Chironectes minimus · also called yapok
Diving beneath the surface of a quiet stream, a water opossum sweeps its webbed hind feet to pursue a fish, the only marsupial anywhere in the world built for a genuinely aquatic life, its pouch sealed tight to keep the water out.
Overview
The water opossum, Chironectes minimus, also known as the yapok, is the only fully aquatic marsupial species in the world, native to wetland and rainforest habitat across a broad range extending from southern Mexico through Central America and much of South America. Its webbed hind feet, water-repellent fur, and sealable pouch found in both sexes make it one of the most physically specialised and genuinely unique marsupials found anywhere on Earth.
A pouched mammal that learned to swim
While nearly every other marsupial stays firmly on land or in the trees, the water opossum instead built its entire life around freshwater streams, evolving webbed feet, water-shedding fur, and even a waterproof pouch to make aquatic life possible.
Status
Least Concern, though its elusive, nocturnal, aquatic habits make detailed population trends genuinely difficult for researchers to establish with confidence.
Water Opossum: common questions
Why is the water opossum considered unique among marsupials?
This species is the only marsupial species anywhere in the world adapted for a fully aquatic lifestyle, spending much of its active time swimming and foraging underwater for fish and other aquatic prey, a lifestyle unmatched by any other pouched mammal.
How does the water opossum swim so effectively?
This species has large, webbed hind feet that function as effective paddles, combined with dense, water-repellent fur that keeps its skin dry even during extended time in the water, together allowing it to swim and dive efficiently in pursuit of prey.
Why do male water opossums have a pouch too?
Both males and females of this species have a pouch that can be sealed tightly with a ring of muscle, and in males this pouch protects external anatomy from the water while swimming, an adaptation not found in most other pouched mammals, where pouches serve only females.
What does the water opossum eat?
This species feeds on fish, crustaceans, and aquatic insects, locating and capturing prey underwater using highly sensitive whiskers on its front paws that allow it to detect movement even in murky or low-visibility water.