are over 300 species of shrews in 23 genera, making the Soricidae the largest
family of lipotyphlans in terms of species number. Its members can be found
throughout the world, except for the polar regions, Australia, and southern
South America. Shrews possess characteristically long, pointed noses, which
aid olfaction as well as burrowing into the ground as they forage for invertebrates.
Although they possess small external ears, hearing and olfaction are acute.
The skulls of shrews are long and narrow, usually with a flat profile. They
lack zygomatic arches, auditory bullae, and postorbital processes. The dental
formula is: i3/1-2, c1/0-1, pm1-3/1, m3/3 = 26 - 32. The first incisor is
large and is made up of two very distinct cusps. The anterior cusp is elongate
and projecting, resulting in the second being often mistaken for an additional
tooth. The canines and pre-molars are small and peg-like. The upper molars
are dilambdodont. Shrews lose their milk teeth before birth, and therefore
tooth wear can become a problem in adult life. Older adults may starve to
death when their teeth become too worn to function.
are notoriously small, (the pygmy white-toothed shrew is the smallest extant
mammal weighing a mere 2-3 grams at adult weight). Their small size dictates
a high metabolic rate, thus requiring an almost constant input of food items.
Shrews are therefore cathemeral and have a voracious appetite, feeding primarily
on invertebrates. Some shrews possess toxins in their saliva that allow
them to hunt and kill larger prey, including small vertebrates, (such as
frogs). The skin glands of many species contain similar toxins that are
exuded as secretions when threatened, rendering them unpalatable to many
carnivores. Soricids are typically terrestrial, though some are aquatic.
The Tibetan water shrew (Genus Nectogale) is the only species with webbed
feet, although other aquatic species, for example the European water shrew
(Genus Neomys), have feet, toes, fingers and tail fringed with stiff hairs.
These hairs increase surface area and aid propulsion.
offspring of the genera Crocidura and Suncus exhibit an unusual feature
known as 'caravanning', in which they grip the rump of the sibling in front
while the leading sibling grips the rump of the parent. The parent then
leads the offspring around the terrain of their habitat. (The grip is strong,
and the whole caravan may be lifted off the ground intact by picking up
Neomys fodiens (European Water Shrew)