The Mustelids all have one thing in common, they all have scent glands. They use their scent glands to mark off what is their territory so no other of their kind come and try to live there. The glands are about the size of a marble and are in their anus. This scent is given off when they are scared or when they mark their territory. The Mustelids vary in size.
Otters live on land and in water whereas most of the Mustelids live either in trees or on land.
River otters are in the Class Mammalia, their Order is Carnivora, their family is Mustelidae, their genus and specie is Lutra Canadensis. Pictures taken by the Twin Groves Virtual Wetlands Team during a 1998 field trip to Brookfield Zoo. Created for the Museums in the Classroom program sponsored by Illinois State Board of Education , the Brookfield Zoo , the Illinois State Museum. , and Kildeer Countryside CCSD 96.