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—and many other insects—can survive decapitation, it helps to understand why humans cannot, explains physiologist and biochemist Joseph Kunkel at the
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.”