Shrews are tiny mammals that have been widely characterized as simple and primitive. This traditional view is challenged by a new study of the hunting methods of an aquatic member of the species, the water shrew. It reveals remarkably sophisticated methods for detecting prey that allow it to catch small fish and aquatic insects as readily in the dark as in daylight.
It is a skill set that the water shrew really needs. About half the size of a mouse, water shrews have such a high metabolism that they must eat more than their weight daily and can starve to death in half a day if they can't find anything to eat. As a result, water shrews are formidable predators ounce for ounce.
"Water shrews do much of their hunting at night so I began wondering how they can identify their prey in nearly total darkness," says Ken Catania, the associate professor of biological sciences at Vanderbilt who headed the study.