[5] The American water shrew is a sexually dimorphic species in which the males are generally larger and heavier than the females.

[4] When underwater, the animal appears to have a silver veneer on account of its water repellent fur trapping air bubbles.

[3] American water shrew populations span the central and eastern regions of Canada and the northern United States, as well as a small isolated section of the Appalachian mountain range.

Most remarkable about this behavior is that water shrews are mainly nocturnal hunters, meaning they don't use eyesight while locating their prey underwater.

While it has been suggested that water shrews may use sonar or electroreception for this purpose, all investigations into these claims have produced no supporting evidence.

According to Kenneth C. Catania's research, nocturnally diving shrews manage to locate their prey in the obscured stream by detecting movement along their whiskers or by “underwater sniffing,” a strategy in which they exhale air bubbles onto a perceived target and then re-inhale their own air bubbles to confirm the presence of prey.