Physical characteristics

Soricine shrews are small mouse-sized insectivores with a pointed snout, short legs, and usually a long tail. The smallest soricines (Sorex minutissimus, Sorex hoyi) have a body mass of 0.07-0.1 oz (2-3 g), and are among the smallest known mammals. The size of the largest soricines slightly exceeds that of the house mouse. The largest representatives of the subfamily, water shrews of the genus Chimarrogale, weigh up to 1.5 oz (40 g), their head and body length ranges up to 5.3 in (13.5 cm), while tail length can be up to 5 in (12.5 cm). They walk on the soles of their feet, which have five clawed

A desert shrew (Notiosorex crawfordi) eating a centipede. (Photo by Jack Couffer. Bruce Coleman, Inc. Reproduced by permission.)

digits. The eyes are extremely small and their sight is poor, but the sense of smell is keen as indicated by long, mobile snouts. The external ears are usually hidden in their fur. Pelage is usually dark, with brown, grayish, or black coat color. The skull is narrow and elongated, and the brain is small and smooth, dominated by large olfactory bulbs.

Certain skeletal and dental characters are diagnostic for the subfamily: the articulation of the mandibular condyle, the position of the mental foramen, and the morphology of the lower premolar. The dentition is highly specialized and similar from species to species. They have continuous rows of teeth classified as incisors, antemolars, premolars, and molars. Homologies of the antemolars are difficult to determine and thus, the dental formula is expressed using different terms than in other mammals. The number of antemolars is the only difference seen between living species in the dental formulae. Part of dental variation in soricines is clearly correlated with ecological adaptations.

In most of the Soricinae, a reddish, iron-containing pigmentation on cusps of their teeth is present. The function of tooth pigmentation is not yet clearly understood, but it is supposed that pigmented enamel should be harder than un-pigmented and should provide a protection against abrasion. The intensity of pigmentation varies. Some species (Blarina, Blarinella, Sorex daphaenodon) have a very strong dark pigmentation, other species (Anourosorex, Chimarrogale, Necto-gale) appear to have reduced red enamel or even unpigmented teeth. The absence of tooth pigment may also be explained by ecological, particularly dietary, factors.

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