Marine Biology

The Diet and Feeding Habits of the River Otter



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"The Diet and Feeding Habits of the River Otter"
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With an acrobatic dive to the bottom of the murky river, the river otter seizes a crayfish in its mouth. It rises to the surface and then lies on its back holding the prey in its small forearms as it enjoys its catch.

The river otter is a successful predator that prefers to follow rivers and its tributaries, but can also be found in nearby lakes and marshes that are bordered by woods.

As master divers, the river otters can stay underwater for up to four minutes. During this time they close their ears and nostrils. This is evidence that the otter does not use hearing to catch its prey. One of the unique characteristics of the otter is that it has very sensitive whiskers and tufts of hair on its elbows that detect movement in the water. This way the otters sense where to locate their prey.

Once they have located the prey, most otters catch the prey with their mouths, although some species do use their front forearms to catch the prey. They eat the prey immediately usually by floating or lying on their backs and holding the prey in their front paws. Using well-developed molars they crush their prey. Consuming one of their favorite prey, fish, is done head first and then the otter disposes of the fins, not eating them.

In the summer the otter feasts on crayfish, but in the winter the diet relies more heavily on fish. The otter likes small and large mouth bass, sunfish and rock bass, but will also eat sluggish types of non-game fish.

Fish farmers are aware of the economic damages that can occur due tothe otter. A group of hungry otters can decimate a fish farm very quickly. Eating inch long bass fingerlings, it is nothing for the otter to consume 17 fingerlings at one sitting. This winter desire for fish often causes conflict with humans, which are their main predator.

Other supplemental forms of food for the otter's diet include: snails, small birds, frogs, salamanders, clams, snakes, insects and their larvae. They will even eat small mammals such as muskrats. In the spring baby birds such as ducks make a meal for the ravenous otters.

The otter has a high metabolism which allows it to move so quickly and agily in the water, but in order to do this the otter must consume food often and will need to hunt frequently. Try, try again would be the motto of the otter. Believe it or not, less than 20% of their diving expeditions in the water results in prey, so the otter needs to spend much of its energy in the pursuit of food.

After consuming its prey the otter appears to be cleaning up after its meal. It is known to clean its face and whiskers by rubbing them on the grass or snow.

The river otter is a resourceful and sly predator of the muddy, murky rivers and swamps.

Sources consulted in the writing of this article include:

www.zoo.org
www.riverotter.net (River Otter Preservation Society)
www.dnr.gov (Department of Natural Resources)
National Geographic
www.luddist.com

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