Its mass may range from 5 to 13 g (0.18 to 0.46 oz) and it possesses thirty-two teeth with an average metabolism of 4.7 kilocalories a day.

[3] Arctic shrews are found in a variety of habitats in highest density of 3 to 5 individuals per acre and each individual Arctic shrew appears to limit its range to one tenth of an acre.

In the Upper Peninsula of Michigan, they are found densely in spruce and tamarack swamps, in addition to other typical habitats.

Arctic shrews have been found in clearings in boreal forests, and occasionally in mixed conifer swamps, dry or old fields, dense grasses near ditches, mixed grasses, in the undergrowth of forest clearings, alder thickets, and dry marsh with grasses, hammock sedges , forbs, cattail, willow, and red-osier shrubs.

The gestation period ranges between 13 and 21 days, so the young stay with their mother until 5 to 6.5 weeks after conception, and males make no contribution to parental care.

Both female and male Arctic shrews reach sexual maturity after one year.

It eats insects, worms and small invertebrates, with a large proportion of its diet made up of larch sawflies, though Arctic shrews in captivity have been fed dead voles, fly pupae, and mealworms.