Beetles are by far the largest order in the insect class, rodents are the largest order in the mammal class.
Rodents do not inhabit oceans or large lakes, but are found from the Arctic to the dry land of the Antarctic.
Rodents have 2 upper and 2 lower chisel-like teeth called incisors. These are in the front of the mouth with a space between them, and the grinding teeth behind them. These are large, very hard, and very sharp teeth used for gnawing.
image courtesy of Mirriam-Webster Online Visual Dictionary
Common rodents include mice, rats, squirrels, chipmunks, gophers, porcupines, beavers, hamsters, gerbils, and guinea pigs.
Rodents have sharp incisors that they use to gnaw wood, break into food, and bite predators.
Most eat seeds or plants, though some have more varied diets.
They have historically been pests, eating human seed stores and spreading disease. Rodents evolved some time around the end of the Cretaceous period c 65 million years ago. In terms of number of species — although not necessarily in terms of number of organisms (population) or biomass — rodents make up the largest order of mammals, with over 40 percent of mammalian species belonging to the order. Their success is probably due to their small size, short breeding cycle, and ability to gnaw and eat a wide variety of foods.(Lambert, 2000) There are about 2,277 species of rodents, about 42% of all mammal species.
Rodents are found in vast numbers on all continents except Antarctica, most islands, and in all habitats except for oceans. from ScienceDaily.com
Most rodents have four toes on each front foot, and five on each hind foot.
Rodents are an important group, aiding in destroying weed seeds and insects. They themselves are food for meat-eating animals that might prey on man's poultry or livestock. Rodents destroy more property than other mammals, but they are also more useful than most other wild animals. Soil development and tree planting are tasks performed by rodents.
Rodents build dams that help preserve the water supply of the forests.
Of all the rat species, the Brown rat is the most destructive known to man.
Beavers and muskrats are valuable for their fur.
Mammals at Our Homeschooling Journey blog
Rodents resources at HomeschoolShare