Mammal
Mammal
Yapok (Water Opossum)
Chironectes minimus
The Yapok, or Water Opossum, is the only truly aquatic marsupial in the world and one of Trinidad's least-seen mammals.
The Yapok, or Water Opossum, is the only truly aquatic marsupial in the world and one of Trinidad's least-seen mammals. Superficially otter-like with webbed hind feet and dense water-repellent fur, it hunts fish and crustaceans in rivers and streams by night, and is unique among marsupials in that both sexes possess a watertight pouch, allowing the female to carry young, and the male to protect his genitals, while swimming.
Identification
The Yapok has a streamlined body covered in short, dense, water-repellent grey fur banded with black, giving a marbled appearance unlike any other Trinidad mammal. The hind feet are large and fully webbed for swimming, while the forefeet remain unwebbed and dexterous, used for feeling along the riverbed and streambanks for prey. Long, sensitive whiskers aid foraging in murky water. Adults measure around 25 to 40 cm in body length, with a long, scaly, rat-like tail nearly equal to body length used as a rudder while swimming.
Ecology
Strictly nocturnal and aquatic, the Yapok forages in slow-moving rivers, streams, and freshwater pools, diving and swimming with powerful strokes of its webbed hind feet to catch fish, crustaceans, and aquatic insects, which it manipulates and eats using its sensitive forepaws. By day it shelters in burrows dug into riverbanks, often with an entrance just above the waterline. Uniquely among marsupials, both males and females have a pouch: the female's carries and nurses young even while she swims, sealed by a strong sphincter muscle, and the male's houses the external genitalia to keep them protected and streamlined during swimming.
Status in T&T
The Yapok is present in Trinidad's rivers and freshwater systems but is rarely encountered due to its nocturnal, aquatic habits and naturally low population density. It is not considered globally threatened, but clean, unpolluted, slow-flowing freshwater habitat with intact riverbank vegetation is essential to its survival, and it is highly sensitive to water pollution and stream degradation. It receives general protection as native wildlife under the Conservation of Wildlife Act and is not a game species.
Threats
- Freshwater pollution and sedimentation
- Riverbank vegetation clearance
- Damming and stream channelisation
- Low natural population density
