AT A GLANCE
- Common Name: Giant Otter Shrew
- Scientific Name: Potamogale velox
- Category: Mammals
- Subcategory: Afrosoricida
- Range: Equatorial Central Africa, from Nigeria and Cameroon east across Gabon, Republic of the Congo, Democratic Republic of the Congo, Central African Republic, to western Uganda and northern Angola
- Habitat Type: Fast-flowing, clear forest rivers, rocky streams, sluggish blackwater swamps, and mountain torrents in pristine lowland and montane rainforests up to 1,800 meters elevation
- IUCN Red List Status: Least Concern
- Lifespan: 4 to 7 years
- Diet: Carnivorous/Aquatic predator (freshwater crabs, river prawns, small fishes, water beetles, and aquatic amphibians)
- Average Size/Weight: Head-and-body length 28 to 35 cm; tail length 24 to 29 cm; weight 300 to 1,000 g
- Key Defining Feature: Extraordinary semi-aquatic afrotherian resembling a miniature otter, possessing a powerful laterally flattened fish-like tail that it swishes from side to side to swim like a crocodile
Overview
The Giant Otter Shrew (Potamogale velox) is an extraordinary and ancient semi-aquatic mammal endemic to the tropical rainforests of the Congo Basin and equatorial West Africa. Despite its common name, it is neither a true otter nor a shrew, but rather a member of the family Tenrecidae (subfamily Potamogalinae) within the superorder Afrotheria. Looking like a miniature, velvet-coated otter, it is the only living mammal that propels itself through the water using a laterally flattened, rudder-like tail moved from side to side in serpentine undulations, exactly like a fish or crocodile.
Biology and Physical Characteristics
Potamogale velox possesses a streamlined, elongated body with a dense, silky double coat consisting of a woolly, waterproof underfur overlaid with flat, glistening guard hairs of dark glossy brown or black, contrasting with a creamy-white underbelly. Its broad, flattened muzzle is surrounded by an enormous array of stiff, white, highly innervated vibrissae (whiskers) used to detect prey in murky water. Remarkably, its feet are completely unwebbed; all aquatic propulsion is generated by its heavy, muscular tail, which is deeply compressed laterally (flattened from side to side like a knife blade) and keeled along the dorsal edge.
Behavior and Ecology
Exclusively nocturnal, the Giant Otter Shrew spends the daylight hours resting inside dry nesting chambers excavated into riverbanks, entered via underwater tunnels. At nightfall, it dives into swift-running forest streams to hunt. Swimming with powerful lateral strokes of its tail while tucking its unwebbed feet tightly against its torso, it navigates rocky rapids with torpedo-like speed. It feeds heavily on freshwater crabs and prawns, using its strong jaws and sharp teeth to crush heavy chitinous carapaces before carrying them to dry gravel banks to consume. Highly territorial, individuals maintain solitary patrol stretches along streams, depositing distinct latrines at territorial boundary pools.
Conservation and Human Impact
The Giant Otter Shrew is currently assessed as Least Concern on the IUCN Red List due to expansive range across the intact forests of the Congo Basin. However, it is experiencing localized declines from heavy river siltation caused by logging and road construction, soil erosion from slash-and-burn farming, and accidental drowning in gillnets and fish traps set by local river fishermen. It is also trapped for its luxuriant, waterproof pelt in certain regions.
Interesting Factoid
Unlike otters or beavers that paddle with webbed feet or flat horizontal tails, the Giant Otter Shrew has unwebbed feet and a vertically blade-like tail that it swishes side-to-side, swimming through rapids exactly like a miniature crocodile.