This article is about the animal; see also The Taming of the Shrew for the use of this term to describe a person.
Shrews are small, superficially mouse-like mammals of the family Soricidae. Although their external appearance is generally that of a mouse with a long nose, the shrews are not rodents and not closely related: the shrew family is part of the order Eulipotyphla. Shrews have feet with five clawed toes, unlike rodents, which have four. Shrews are also not to be confused with tree shrews, which are also unrelated, and belong to their own order, Scandentia.
There are 368 species of shrew in 23 genera, which are grouped into three subfamilies: Crocidurinae (White-toothed shrews), Myosoricinae (African white-toothed shrews) and Soricinae (Red-toothed shrews). Shrews are distributed almost worldwide: of the major temperate land masses, only New Guinea, Australia, and New Zealand do not have native shrews at all; South America has shrews only in the far-northern tropical part. In terms of species diversity, the shrew family is the second or third most successful mammal family of all, being rivalled only by the Muroidea families Muridae and Cricetidae.
In general, shrews are terrestrial creatures that forage for seeds, insects, nuts, worms and a variety of other foods in leaf litter and dense vegetation, however some specialise in climbing trees, living underground, or even an aquatic lifestyle. All shrews are small, most no more than mouse size. The largest species is the House Shrew (Suncus murinus) of tropical Asia which is about 15 cm long and weighs around 100 grams; several are very small, notably the Pygmy White-toothed Shrew (Suncus etruscus) which at about 3.5 cm and 2 grams is regarded as one of the smallest living mammals.
Unlike most mammals (with the notable exception of the platypus), some species of shrew are venomous.
Shrews have a high metabolic rate and so must feed almost constantly when not sleeping. Shrews are not able to hibernate.
Unlike most other mammals, shrews are born with permanent teeth.