Cockroaches are cold-blooded and can survive weeks or even months without food. Because they have open circulatory systems and can breathe through tiny holes in their body segments, they do not need to carry a head or any other part of their body. Their lack of a head also allows them to live without water. However, if they are separated from a source of water, they will soon die of dehydration.
Cockroaches have evolved to survive in a variety of environments. For example, a fully grown cockroach can fit into a coin-sized hole or crevice. Their amazing ability to hide means that even a single cockroach can live for months or even years without feeding. They can survive in the dark and scavenge food from paper, fingernails, and hair.
Cockroaches have a highly complex genetic code. In fact, their genome is the second-largest of all insects. It contains about 60 percent repetitive segments. Cockroaches also possess large gene families related to taste and smell. For example, American cockroaches have 522 gustatory receptors and German cockroaches have 545.
Cockroaches can survive atomic bombings and radiation. In fact, cockroaches were found to have survived the atomic bombings of Hiroshima and Nagasaki. In addition, they seem to be incredibly resilient to gamma rays.