The rat is the most numerous species of mutants in the Zone. Many animals had to mutate in order to win in the Area their right to life. But the gray rats the already brilliant masters of survival. The rats are not people from the underground laboratory complexes, they are true masters of the Zone, but not her children. Perhaps are carriers of anthrax. It is difficult to imagine a more fit body. Radiation and anomalies practically did not affect the rat's physiology and made them learn to recognize new dangers. This well-known resistance of rats to the effects of radiation exposure due to the effectiveness of their repair systems for DNA. The rapid reproduction and large number of children allow them to quickly adapt to the new environment.