The Norway Rat has a stocky, powerful build. Like all rats it has a slender, scaly tail and long, sharp claws. There are between 180 and 200 rings on the tail, which is shorter than the body. Length ranges from 8 to 10 inches, not including the tail, and the weight up to 16 ounces. The ears are small, the snout blunt, and the fur coarse. Color varies from brownish-gray to reddish-gray. Lab rats (albinos) are descended from brown rats. They originated in Asia, and spread throughout the world on ships and overland. Like all rodents, they have chisel-like front teeth especially suited for gnawing.