Question
Dear Jim how is it that cockroaches can live through alomost anything a human can't?

Answer
What is it about a cockroach that makes it seem to live through anything, existing even after the dinosaurs became extinct? The answer is in its biology. Cockroaches belong to the insect order Blattodea and there are about 3,500 different species throughout the world. They've been on the earth for at least 250 million years, even predating the dinosaurs by about 15 million years.

These insects are hardy because they can eat almost anything, including paper, wood or even glue. Experiments have also shown that they are quite intelligent and can learn and adapt to situations amazingly fast. They have even been taught to run in mazes and remember the route of the maze from day to day. This ability to learn and adapt to new things makes these insects able to withstand sudden changes. They are also known to become resistant to pesticides quickly and are therefore very difficult to poison.

Since we know cockroaches have been around for millions of years, surviving through the extinction of the dinosaurs, ice ages and other catastrophic climate changes, what else could they live through? Could these hardy insects possibly survive a nuclear war? The facts surrounding this question might amaze you. Research has been done on exposure to radiation on humans and cockroaches. People can survive a single exposure of 5 rems (a 'rem' is an amount of radiation that will cause harm to human tissue), but 800 rems will kill a person. Cockroaches, however, can tolerate a much higher dose of radiation. The American cockroach can survive after being exposed to 67,500 rems and the German cockroach can tolerate between 90,000 and 105,000 rems. This would equal the amount of radiation from a nuclear explosion.

Combined with these amazing survival abilities to withstand incredible odds, cockroaches also manage to produce large quantities of equally hardy offspring. Each female cockroach can produce hundreds of eggs during her short life span. The adult Australian cockroach lives for about 4-8 months, the American roach for about 6-12 months and the Oriental cockroach for about 3-6 months. Even with such a short life, the females, depending on the species, can produce up to 40 egg cases with as many as 50 eggs per case. Therefore, even if the female dies shortly after reaching maturity, she could already have laid many eggs. A female German cockroach can produce up to eight egg cases in her lifetime for a total of about 300 babies. In about two months, the young, or nymphs, are mature enough to reproduce. If you suppose that half of these 300 are female, that's another 300 offspring per female. In another 60 days, those females will reproduce. Within a year, you can have over 100,000 cockroaches from that original female.

With a rapidly growing population like that, it's important to do a little prevention, unless you want a houseful of roaches. The easiest thing to do is keep your house clean. Roaches are opportunistic and will set up house where there's a steady food supply, so sweep and vacuum often. Once you see a roach, be assured that it's not alone. There are a variety of pesticides on the market, but make sure to use them sparingly, especially is you have pets or children in the home. With care and cleanliness, roaches can be eliminated and kept out of your living space. But remember, they've been around a lot longer than we have and have managed to survive unbelievable odds, so perhaps we should give them a little credit as well.

Cockroaches are infamous for their tenacity, and are often cited as the most likely survivors of a nuclear war. Some even claim that they can live without their heads. It turns out that these armchair exterminators (and their professional brethren) are right. Headless roaches are capable of living for weeks.

To understand why cockroaches梐nd many other insects梒an survive decapitation, it helps to understand why humans cannot, explains physiologist and biochemist Joseph Kunkel at the University of Massachusetts Amherst, who studies cockroach development. First off, decapitation in humans results in blood loss and a drop in blood pressure hampering transport of oxygen and nutrition to vital tissues. "You'd bleed to death," Kunkel notes.

In addition, humans breathe through their mouth or nose and the brain controls that critical function, so breathing would stop. Moreover, the human body cannot eat without the head, ensuring a swift death from starvation should it survive the other ill effects of head loss.

But cockroaches do not have blood pressure the way people do. "They don't have a huge network of blood vessels like that of humans, or tiny capillaries that you need a lot of pressure to flow blood through," Kunkel says. "They have an open circulatory system, which there's much less pressure in."

"After you cut their heads off, very often their necks would seal off just by clotting," he adds. "There's no uncontrolled bleeding."

The hardy vermin breathe through spiracles, or little holes in each body segment. Plus, the roach brain does not control this breathing and blood does not carry oxygen throughout the body. Rather, the spiracles pipe air directly to tissues through a set of tubes called tracheae.

Cockroaches are also poikilotherms, or cold-blooded, meaning they need much less food than humans do. "An insect can survive for weeks on a meal they had one day," Kunkel says. "As long as some predator doesn't eat them, they'll just stay quiet and sit around, unless they get infected by mold or bacteria or a virus. Then they're dead."

Cockroach decapitation may seem macabre, but scientists have conducted many experiments with headless roach bodies and bodiless roach heads. Decapitating roaches deprives their bodies of hormones from glands in their heads that control maturation, helping researchers investigate metamorphosis and reproduction. And studies of bodiless roach heads shed light on how their neurons work. Plus, it provides just one more testament to the cockroach's enviable endurance.