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Cockroaches are generally omnivores. An exception to this is the wood-eating genus Cryptocercus, with various species found in Russia, China, Korea and the United States. Although they are incapable of digesting the cellulose themselves, they have a symbiotic relationship with a protozoan that digests the cellulose, allowing them to extract the nutrients. In this, they are similar to termites and current research suggests that the genus Cryptocercus is more closely related to termites than it is to other cockroaches. Cockroaches are most common in tropical and subtropical climates. Some species are in close association with human dwellings and widely found around garbage or in the kitchen.

Cockroaches, like all insects, breathe through a system of tubes called tracheae. The tracheae of insects are attached to the spiracles, excluding the head. Thus the cockroach can breathe without its head. The valves open when the CO2 level in the insect rises to a high level; then the CO2 diffuses out of the tracheae to the outside and fresh O2 diffuses in. The tracheal system brings the air directly to cells because they branch continually like a tree until their finest divisions tracheoles are associated with each cell, allowing gaseous oxygen to dissolve in the cytoplasm lying across the fine cuticle lining of the tracheole. CO2 diffuses out of the cell into the tracheole.

Cockroaches can survive decapitation for a very long period compared with humans, but of course become unable to fend for themselves and eventually die.

Female cockroaches are sometimes seen carrying egg cases on the end of their abdomen; the egg case of the German cockroach holds about 30–40 long, thin eggs, packed like frankfurters in the case called an ootheca. The eggs hatch from the combined pressure of the hatchlings gulping air and are initially bright white nymphs that continue inflating themselves with air and harden and darken within about four hours. Their transient white stage while hatching and later while molting has led to many individuals to claim to have seen albino cockroaches.

The cockroach is also one of the hardiest insects on the planet, capable of living for a month without food; being able to survive even on the glue from the back of postage stamps. It can also hold its breath for 45 minutes and has the ability to slow down its heart rate.

It is popularly suggested that cockroaches will "inherit the earth" if humanity destroys itself in a nuclear war. Cockroaches do indeed have a much higher radiation resistance than vertebrates, with the lethal dose perhaps 6 to 15 times that for humans.

The cockroach's ability to withstand radiation better than human beings can be explained in terms of the cell cycle. Cells are more vulnerable to effects of radiation when they are dividing. A cockroach's cells divide only once when in its molting cycle, which at most happens weekly. The cells of the cockroach take roughly 48 hours to complete a molting cycle, which would give time enough for radiation to affect it but not all cockroaches would be molting at the same time. This would mean some would be unaffected by the initial radiation and thus survive, at least until the fallout arrived.

Sources

• Wikipedia

Approximate Dimensions: 3"x2"x1"