There is an incredible world of animals, insects and plants that live in or near rivers and lakes. Some of these animals are semi-aquatic. That means they can live in the water part-time and on the land the rest of the time. Two animals that you will find along the waterways are the nutria and the beaver, both are rodents. But other than that, they are very different. One is aggressive and harmful to the environment and the other one is an engineer building constantly. Nutria have long skinny tails, long yellow teeth and have been given the nickname, water rat.

The two rodents have glands which make oil that coats their two layers of fur, making  them waterproof. It's like having their very own wetsuit. The natives of  North America liked this fur and used the pelts of the beaver to make clothes, trade them with other tribes, and they were a good source of food. People in South America used the nutria in the same way. The explorers of the new world learned about these animals and began trapping them to sell. Beavers have fewer babies or kits than nutria do every year. This meant beavers soon became an endangered animal. From the late 1800s to the 1940s people began looking for a way to make money.  They knew about the nutria in South America so they brought some to the United States and began farming them. The farms didn’t work out and a lot of the nutria were released into the wild.

Alright, imagine you're a beaver. You’re kind of like nature’s engineer. You use your long teeth to cut down trees. The dam you build creates a pond. In the midle of the pond you build your den, but more than that, you change the environment in a positive way. The dam causes water to build up creating wetlands. You have created new habitats for animals to move into.  The frogs, fish and birds all love you, but then, a new kid moves into the neighborhood.

Here's the problem: nutria are really good at eating plants but they are not good neighbors! When they munch on plants, they don't just eat the leaves but they also eat the roots. The roots help hold the soil together. Nutria might look cute, but they can really mess up the environment. Nutria have spread to many places in the U.S. and started taking over. They don’t have any natural predators (like big cats or wolves) to keep the population controlled, so they grow in huge groups, eating a lot of plants. This makes a mess of the environment. Nutria are not part of the local ecosystem. They eat plants that other animals need to survive. So, when an animal like this shows up, they “invade” and make things hard for the plants, animals, and even people living there. Animals like this are called invasive species.

It’s always a good idea to avoid touching or getting too close to wild animals like nutria or beavers. Both nutria and beavers can carry diseases that might make people or other animals sick. Most of the diseases are caused by parasites like Giardia and Toxoplasmosis. Both of these animals have also been known to carry rabies. Rabies is a disease that affects the brain. This causes animals to become aggressive and they may attack humans. This doesn’t happen often, but if you are in a place that has wild animals, no matter how cute they look, leave them alone.