These facts about the two kinds of rats that love to live around people—brown rats (a.k.a. Norway rats, Rattus norvegicus) and black rats (a.k.a. When rats bite, they mean business. The long claws on a rat’s feet allow it to scale brick or cement walls with Spider-man-like ease. According to one study [PDF], rats can lift objects that weigh nearly a pound—more than the average rat’s body weight.