Shrews are often mistaken for rodents due to their small size and mouselike appearance, but they belong to a different mammalian order, Eulipotyphla, making them more closely related to moles and hedgehogs. This article highlights the distinctive features of shrews, showing how they differ from common small mammals like mice and moles.
General Physical Traits
Shrews are among the smallest mammals, with most species no larger than a mouse. Their slender, cylindrical bodies allow them to navigate dense undergrowth. They generally measure between 5 to 10 cm in length, including the tail, and weigh 2 to 30 grams.
Their fur is dense and velvety, providing insulation and protection. Fur colors vary across species, commonly appearing in shades of brown, gray, or black, sometimes with lighter undersides. Tail length relative to the body also differs significantly among species.
Key Distinguishing Features
A shrew’s most recognizable feature is its long, pointed snout, which twitches as the animal explores. This snout is equipped with numerous whiskers that aid navigation and prey location, especially given their poor eyesight. Mice typically have blunter noses, while moles, though also pointed, often have less prominent or hairless snouts.
Shrews possess extremely small, bead-like eyes, often barely visible within their dense fur, indicating a reliance on senses other than sight. Their ears are also tiny and frequently concealed by fur, unlike mice, which have larger, more noticeable eyes and prominent ears. Moles, specialized for an underground existence, have eyes and ears so tiny they may not be visible.
A defining characteristic differentiating shrews from rodents like mice is their teeth. Shrews lack the chisel-like gnawing incisors of rodents; instead, they have sharp, spiky teeth adapted for hunting insects and other small prey. Many shrew species exhibit unique reddish-tipped incisors due to iron deposits in the enamel, which strengthens the teeth. This pigmentation is concentrated in areas of high wear, unlike rodents whose pigmented enamel is typically only on their incisors. Shrews have five toes on each foot, often with sharp claws, but their feet are not enlarged like the shovel-like front paws of moles, which are specialized for digging.
Diversity in Appearance
While shrews share common physical traits, their appearance varies considerably across the more than 350 known species. Size is a notable variable, ranging from the tiny Etruscan shrew (Suncus etruscus), one of the smallest known mammals at 1.8 grams and 4 cm, to larger species like the Asian house shrew (Suncus murinus) or the Northern short-tailed shrew, which can be up to 15 cm long and weigh around 100 grams.
Subtle differences in fur color and texture are also observed, often influenced by habitat or geographic location. Some species may have tricolored fur with distinct dark backs, grayish sides, and paler undersides. Specialized adaptations are present in certain species, such as water shrews. These shrews have stiff hairs fringing their feet and a keel-like fringe of hairs on their tail, which aid propulsion and steering in water. Their fur is also denser and water-repellent, helping them maintain body temperature while submerged.