Mammals Active at night

Water Opossum

Chironectes minimus

iNaturalist Wikipedia

Meet the world's only aquatic marsupial, a nocturnal master of the river with waterproof fur and webbed feet. Elusive and striking, the Water Opossum is the ultimate prize for backyard explorers living near the water's edge.

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Quick Identification

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Size

Body length 27–40 cm (10–16 in), tail length 31–43 cm (12–17 in); weight 600–800 g (1.3–1.8 lbs)

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Colors

Distinctive high-contrast pattern of four or five broad blackish-brown bands over a pale gray or white base; white underbelly; dark facial mask across the eyes

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Key Features

Broadly webbed hind feet for powerful swimming
Unique waterproof pouch present in both males and females
Short, dense, water-repellent fur
Thick, cylindrical tail used as a rudder

When You’ll See Them

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Activity pattern Active at night

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Peak hours 9 PM - 4 AM

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Season Year-round

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Diet A specialized aquatic hunter, the Water Opossum feeds on small fish, crustaceans (especially crabs and shrimp), frogs, and aquatic insects, using its highly sensitive front paws to feel for prey under rocks.

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Habitat Edges of freshwater streams, rivers, and lakes within tropical and subtropical forests and wetlands.

Behavior

The Water Opossum, or Yapok, is a remarkable evolutionary outlier: it is the world's only truly semiaquatic marsupial. Almost exclusively nocturnal, it spends its nights navigating freshwater streams and lakes with surprising agility. While it moves with a somewhat clumsy waddle on land, it is a master of the water, using its powerful, webbed hind feet to propel itself while its long, hairless tail acts as a precision rudder.

These animals are solitary and highly territorial, living in burrows dug into riverbanks with entrances just above the water line. One of their most fascinating biological traits is the pouch; in females, a strong sphincter muscle seals the pouch completely, keeping the young dry even when the mother is diving for food. Males also possess a pouch, which they use to protect their genitalia from cold water and tangled vegetation while swimming.

Because of their strictly nocturnal habits and preference for dense riparian cover, they are rarely seen by humans. They are sensitive to water pollution and habitat degradation, meaning their presence is often a sign of a healthy, clean freshwater ecosystem. In areas where human development nears their streams, they may occasionally pass through backyard gardens that border natural waterways.

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Camera Tips

Capturing the elusive Water Opossum requires a strategic water-side setup. Unlike terrestrial opossums, the Yapok will rarely venture far from the shoreline. Position your camera on a sturdy stake or tree trunk roughly 1 to 2 feet above the ground, angled downward toward the edge of a slow-moving stream or a shallow riverbank where the animal might climb out to groom or consume its catch. Look for small, flattened areas of vegetation or muddy tracks near the water's edge to identify potential entry and exit points.

Since this is a strictly nocturnal species with a dark, light-absorbing coat, high-quality infrared (IR) flash is essential. Set your camera to a high trigger sensitivity and use 'Burst Mode' or short video clips (15–20 seconds). These animals move quickly in the water, and video is often the best way to distinguish their unique swimming motion from that of a common rodent or an otter. If your camera supports it, high-definition video with audio can capture the distinct splashing sounds they make while foraging.

Baiting for Water Opossums is tricky because they prefer live aquatic prey. However, some researchers have had success using oily fish or pungent sardines in mesh bags secured near the water's edge. Because they use their front paws to feel for food, placing the bait in shallow water (2–4 inches deep) can encourage the animal to stay in the camera's frame longer as it investigates. Ensure your equipment is properly waterproofed, as seasonal rains can cause the water levels of their preferred habitats to rise rapidly.

Similar Species

Species that look similar or are commonly confused with Water Opossum.

Gray Four-eyed Opossum

Lacks the webbed feet and bold banded pattern; has two distinct white spots above the eyes resembling a second set of eyes.

Common Opossum

Much larger with uniform grizzly-gray fur and lacks any adaptations for a semiaquatic lifestyle.

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Frequently Asked Questions

Water Opossums are strictly nocturnal. They emerge from their riverbank burrows shortly after sunset and remain active throughout the night, with peak activity usually occurring between 9 PM and 4 AM.

If your property borders a clean, freshwater stream in their native range, you can attract them by maintaining natural riparian vegetation. They are sensitive to chemicals, so avoiding pesticides near the water is key. You can also try placing fish-based baits near the shoreline.

They are carnivorous foragers. Their diet consists mostly of freshwater crabs, shrimp, small fish, frogs, and aquatic insects. They use their dexterous front paws to feel under rocks and submerged logs for hidden prey.

No, they are generally rare in suburban environments. They require high water quality and dense forest cover. They are most common in remote tropical forests, though they may appear in rural gardens that have undisturbed stream access.

The Water Opossum is easily distinguished by its bold 'marbled' pattern of black and gray bands and its webbed hind feet. Other opossums, like the Common Opossum, have uniform gray or black fur and lack webbing on their feet.

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