North American River Otter

Scientific name - Lontra canadensis

Found throughout North America in riparian zones and in both marine and freshwater habitats.

Physical description - These otters have long, muscular bodies with short legs and webbed feet equipped with claws. They have a long neck attached to a small head, and a strong, long tail. They can range from 26-42 inches, with females being about 1/3 of the males size.

Otter A has a much smaller body than Otter B.

Otter B has a larger tale fit for swimming in rough waters, while Otter A has a smaller tale that can be used to navigate calmer waters.

Otter B has a white chest with dark spots.

Otter A has more fur than Otter B.

Otter B has larger and stronger arms than Otter A.

Otter B has more visible whiskers than Otter A.

Otter B has larger ears that stick out more than Otter A.

Found throughout North America

Aquatic habitats - streams, rivers, lakes, ponds, and marshes

Can live in warm and cold temperature environments

Biomes - freshwater and coastal marine habitats

Food sources for otters - fish, crayfish, crab, frog, bird eggs, bird, and small reptiles such as turtles.

One difference between the North American River Otter and the American Badger is their tails. The badger has a short, shaggy tail, while the otter has a long, strong tail.

Having different tails allows each organism to survive in their environments because the badger's tail is furry, small, and is adapted to survive on land. On the other hand, otter's tails are long and muscular so they can be used to navigate strong currents underwater.

Underwater currents can be rough and without an otter's tail, they can get swept away. This condition can cause the natural selection of this trait because the otters with weak and short tails were not able to survive underwater. American badgers don't have a need for a long strong tail, so natural selection may have badgers with smaller tails survive over badgers with big floppy tails.

Scientific name - Salmo trutta

Environment - Found throughout North America in rivers, lakes, and streams.

Physical description - The fish often have a brassy look with green to yellow sides. They have dark spots on the top, with fins that allow them to move easily through the water. Their size typically ranges from 15-22 inches.

Both can be brown in color.

Both have tails

Both have long, agile bodies

Natural selection is the process by which animals with advantageous traits have the ability to survive and pass those traits on for generations. Traits that aren't beneficial result in organisms with those traits not being able to survive most of the time.

The environment has played a role in North American River Otters and their adaptations because otters have strong tails and long muscular bodies that allow them to push through the water even when there are strong currents. Inherited variation affects these otters by having otters of the same species be varying sizes. Larger otters have larger tails and can move through the environment better than smaller otters, for example. Speciation genetics affect this species as well because they are members of the Mustelidae family, but cannot breed with other members of the family, such as American Badgers. They have evolved separately, which results in them becoming their own species that only allows breeding within the otter species.