This uncommon shrew has a fringe of stiff hairs on the outer side of each hind foot that is a direct adaptation to its aquatic lifestyle. Air bubbles trapped by its fur give this animal great buoyancy but only allow it to be submerged for about 15 seconds at a time.
The beaver is a large rodent adapted for aquatic life. Although awkward on land, it is capable of felling trees eight feet in diameter for construction of its lodge. Details of its engineering prowess make fascinating reading. So, too, is its remarkable recovery in Pennsylvania. The beaver was trapped for its luxuriant fur by early settlers and disappeared from Pennsylvania by the mid-1800s. In the summer of 1917, a pair of beaver from Wisconsin was released in Cameron County. Within five years, the beaver populations of Cameron County and southern McKean County were well established from that original pair. That group and subsequent releases from Canada and New York in 1919, 1920, 1922, and 1924 form the nucleus of the current inhabitants in the Commonwealth.
This rodent is well adapted to semiaquatic life but is not closely related to the beaver. It, too, is valued for its fur. One of its chief enemies is the mink.
Like the skunk and other mustelids, the mink possesses anal scent glands that produce a pungent odor when the animal is stressed.
This animal is well adapted for aquatic life with a streamlined body, thick coat and oily underfur, webbed feet, a muscular, rudder-like tail, ears and nose that can be closed when submerged, and strategic placement of the eyes.
This species is known to wander south of its typical Arctic Ocean habitat and has been sighted several times in the Delaware River. In 1951, a female was taken from the Delaware River near Bristol, Philadelphia County. It was sent to the Section of Mammals by the curator of mammals at the Academy of Natural Sciences, Philadelphia. It is preserved as a skin, skull, and body skeleton in our research collection.