Among the major tropical and temperate land masses, only New Guinea, Australia, New Zealand, and South America have no native shrews.

However, as a result of the Great American Interchange, South America does have a relatively recently naturalised population, present only in the northern Andes.

The largest species is the Asian house shrew (Suncus murinus) of tropical Asia, which is about 15 cm (6 in) long and weighs around 100 g (3+1⁄2 oz)[2] The Etruscan shrew (Suncus etruscus), at about 3.5 cm (1+3⁄8 in) and 1.8 grams (28 grains), is the smallest known living terrestrial mammal.

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 e.g. grass, but some specialise in climbing trees, living underground, living under snow, or even hunting in water.

In some species, exposed areas of the teeth are dark red due to the presence of iron in the tooth enamel.

[7] Apart from the first pair of incisors, which are long and sharp, and the chewing molars at the back of the mouth, the teeth of shrews are small and peg-like, and may be reduced in number.

[10][better source needed] The saliva of the northern short-tailed shrew (Blarina brevicauda) contains soricidin, a peptide which has been studied for use in treating ovarian cancer.

The only terrestrial mammals known to echolocate are two genera (Sorex and Blarina) of shrews, the tenrecs of Madagascar, bats, and the solenodons.

[15][16] By nature the shrew sounds, unlike those of bats, are low-amplitude, broadband, multiharmonic, and frequency modulated.

[16] Except for large and thus strongly reflecting objects, such as a big stone or tree trunk, they probably are not able to disentangle echo scenes, but rather derive information on habitat type from the overall call reverberations.