Otter shrews are small otter-like aquatic mammals in the family Tenrecidae, with silvery fur. The three species of otter shrews belong to the order Insectivora, and all live in central and West Africa near the equator.
The Potamogalinae subfamily includes two genera —Micropotamogale and Potamogale. These genera contain three distinctive species of otter shrew—the giant otter shrew (Potamogale velox ), the Nimba otter shrew (Micropotamogale lamottei ), and the Ruwenzori otter shrew (M. ruwenzorii ).
Giant otter shrew, one of the largest insectivores, is the most common type of otter shrew. These otter shrews have a head and body length of 11.4-13.8 in (29-35 cm) and a tail measuring 9.7-13.8 in (24.5-29 cm). They have small eyes and ears and flattened muzzles with white whiskers. Flaps covering their nostrils act as valves when the animal is submerged, but their feet are not webbed.
Giant otter shrews are insectivores, and have several adaptations for an aquatic life. For example, their elongated bodies and powerful compressed tails resemble those of common otters. These adaptations make otter shrews skilled and rapid swimmers. Further, because of their preference for living near water, they commonly feed on freshwatercrabs, fish, and amphibians. Although giant otter shrews are somewhat clumsy on land, they can move rapidly.
Giant otter shrews are found in the rainforest zone of central Africa including Zaire, Angola, Cameroon, and Gabon, at altitudes up to 1,800 ft (549 m). They inhabit wetlands from muddy bogs to clear mountain streams. These otter shrews dig tunnels in stream banks which they enter from below the water level. In the daytime, otter shrews take shelter in their burrows, and in the late afternoon, they come out to feed and play.
The two species of dwarf African otter shrew in the genus Micropotamogale are about half as large as the giant otter shrew. The Nimba otter shrew, which lives in West Africa, has a head and body length of about 6 in (15 cm) and a tail measuring around 4.3 in (11 cm). Its feet are not webbed. Ruwenzori otter shrews have slightly larger bodies than Nimba otter shrews and their tails are longer and more powerful. Their feet also are not webbed. These otter shrews live in the Ruwenzori Mountains in the Democratic Republic of Congo and Uganda.
The Nimba otter shrew is the rarest species. They are found in Guinea, Liberia, and the Ivory Coast. These small otter shrews prefer to live near shallow water, such as in swampy areas with a lot of undergrowth or small pools of water. Like the giant otter shrew, dwarf otter shrews eat fish, freshwater crabs and insects, and they are most active at night.
The Nimba otter shrew is considered endangered by IUCN-TheWorld Conservation Union. Some portions of its habitat have already been devastated by mining activities and other areas are threatened.