The roof rat is believed to be the same breed of rat that carried the fleas that carried the bubonic plague bacillus that killed 75 million people worldwide from the 1300s to the 18th century. Each year, rats destroy approximately 20% of all the agricultural products in the world. They carry more than 30 diseases harmful to humans, such as typhus, the plague, rat-bite fever, Weil's disease, Chagas' disease, rickettsial pox, tuleremia, Lassa fever, lymphocytic choriomeningitis, and rabies. No other mammal surpasses the rat except man himself in the level of death, destruction, and economic devastation that he causes, Hendrickson writes.

Part of what makes rats so awful and yet amazing is their tremendous survival instincts and physical abilities. Consider these chilling facts:

Rats can swim one-half mile in open water -- that's like swimming the length of Barton Springs Pool two and a half times -- and can tread water for up to three days.

Rats can travel through sewer pipes and dive through water plumbing traps -- more on this later.

Rats can climb brick walls, trees, and telephone poles, and walk across telephone lines. "They get around as good as squirrels, maybe even better," Dotson said.

Rats can fall from a height of 50 feet without getting hurt.

Rats can jump three feet in the air from a flat surface and leap four feet horizontally.

Rats can scamper through openings as small as a quarter: If a rat can get her head through, she's in.

Rats can detect poison mixed with food in as little as two parts per million.

Rats can chew through lead, cinder block, and aluminum sheeting -- rats' teeth grow about four inches a year, and they have to gnaw on things to keep their teeth from pushing through their skulls.