The giant otter shrew is a master of the river, but no true shrew.

Nature · Published 3 October 2026 Swipe more like this →

In short: Despite its name, this nocturnal African predator is neither an otter nor a shrew. It navigates mountain streams using a fish-like, side-to-side swimming motion and possesses a unique, flat tail. While it looks like a river otter, its closest living relatives are actually the tenrecs of Madagascar.

The giant otter shrew (Potamogale velox) is a specialized, amphibious insectivore found across central Africa, from Nigeria to Angola and the Rift Valley. Although it shares the fur texture, body form, and coloration of a river otter, it is significantly smaller, weighing less than 400 grams. It is not a member of the Soricidae family—the true shrews—but belongs to the subfamily Potamogalinae within the family Tenrecidae. Its evolutionary lineage links it most closely to the amphibious tenrecs of Madagascar.

This mammal is perfectly adapted for life in fast-flowing mountain streams and swamps. It hunts nocturnally, relying on sensitive whiskers to detect prey in the water. Its swimming technique is distinct; it propels itself using sinusoidal, side-to-side movements of its body and tail, much like a fish. To maintain a streamlined shape while swimming, it holds its hind feet tightly against its tail. When it catches prey—typically freshwater crabs, fish, or frogs—it returns to the shore to feed, often flipping crabs over to access their softer undersides.

The species is solitary and territorial, with individuals occupying up to 1,000 meters of stream. They den in burrows with underwater entrances, often lining their nests with dry leaves. Despite their specialized adaptations, they are notoriously difficult to maintain in captivity, where they often deteriorate rapidly. In the wild, they face threats from deforestation and soil erosion, which muddy their preferred clear, fast-flowing habitats. While currently classified as a species of least concern, their populations are in decline due to habitat loss and hunting for their skins.

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