The rat is larger than the mouse but smaller than a groundhog. It has a long bald tail. It has a very close relationship with the beaver. It also has a hunched back and long slender teeth. The rat eats nuts, berries, other animals, and gnaws on high fiber material. Rats are small rodents that have plagued humans for millions of years. The female rat carries babies for three weeks until birth. Rats grow about 7-8 inches in length and weigh about 10 ounces. They tend to live about one year. The rat is a furry mammal that is larger than a mouse. There are about 120 kinds of rats. Rats usually dwell in one area unless their food source is scarce.