Shrew, common name applied to certain small mouselike mammals, related to the mole, with a long, pointed snout and soft, gray-brown, velvety fur. Some species are among the smallest of mammals. Most live on the ground, although a few species are semiaquatic or arboreal. Shrews are active, nocturnal animals that feed primarily on insects and worms but also eat mice equal to their own size, as well as plants and occasionally fish and other aquatic animals. Many species have glands from which a fluid with a disagreeable odor is secreted, and some species have a poisonous saliva. Members of one subfamily of shrews hunt by means of echolocation, although this sense is relatively crude compared to its development in bats.

The shrew family is the largest among the insectivores (see Insectivore), and numerous species are found on all major land areas of the world except the polar regions, Australia, New Zealand, Greenland, and Tasmania. In the United States, the most common are the long-tailed shrews and the short-tailed shrews. Long-tailed shrews are slightly less than 7.5 cm (less than 3 in) long. The ears are larger than in some other shrews, and the teeth are brown at the tip. Five to seven young are produced in a litter each spring. The short-tailed shrew known as the mole shrew, the most common shrew in the eastern United States, is about 11.4 cm (about 4.5 in) long. Other insectivores, such as otter shrews, belong to different families. Tree shrews and elephant shrews are not true shrews but belong to separate orders.

Scientific classification: Shrews make up the family Soricidae in the order Insectivora. Long-tailed shrews belong to the genus Sorex. Short-tailed shrews belong to the genus Blarina. The mole shrew is classified as Blarina brevicauda.