A shrew is a small insectivorous mammal of the family Soricidae. Shrews are found in Eurasia and the Americas. They are related to moles, and include the smallest mammals., well under two inches. Light-boned and fragile, with mouselike bodies, shrews are terrestrial and nocturnal and can produce a protective musky odor. They have the highest known metabolic rate of any animal, and therefore, must eat incessantly to survive.