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Cockroaches are one of the most enviable species on Earth, thanks to their ability to survive some of the most life-threatening situations and come out just fine. For example, a cockroach possesses a higher immunity against radiation than humans, (although it cannot survive a nuclear explosion), it can hold its breath for as long as 40 minutes, and it can last for weeks without food.
However, the most amazing thing of all… a cockroach can survive without its head! And not just for a minute or two… a decapitated cockroach can go on living for weeks on end!.
Before we delve deeper into this mystery of roaches’ headless survival, let’s first examine why humans (and almost every other creature on the planet) cannot survive without their precious heads.
Why can’t humans survive without their heads?
It’s an decently well-known fact that humans cannot survive without their heads. There are quite a number of anatomical reasons behind this, but for the scope of this article, we shall address only the one that pertain to the case of headless roaches.
First off, decapitation is followed by a terribly high amount of blood loss, which no human can survive. This rapid bleeding would lead to an inevitable drop in blood pressure, which means that oxygen could not be transported to every part of the body, resulting in death.
Secondly, the nose, which happens to be the chief facilitator of respiration in humans, as it allows for inhalation and exhalation, is located in the head. Without the head, there would be no respiration, and therefore no chance for life to persist. Furthermore, humans eat with their mouth, which is also located in the head. Obviously, that’s another problem. Finally, since practically everything is controlled by the brain sitting at the top of the body, life for humans cannot be imagined without their head.
How can roaches survive without their heads?
Open circulatory system in cockroaches
To start with, there’s a major difference between humans and roaches regarding how blood is circulated throughout their respective bodies. The human body consists of a complex circulatory system with a bunch of arteries, veins and numerous capillaries that criss-cross inside the body to deliver oxygen, as well as vital nutrients, for survival.
On the contrary, roaches have an ‘open’ circulatory system; it’s quite rudimentary and consists of only a small number of components. (Source) This prevents rapid, uncontrolled blood loss following decapitation, as their necks are quickly “sealed off” by clotting.
Respiration in cockroaches
Unlike humans, roaches do not need their heads to breathe in and out, as they do not rely on a single organ to serve that purpose. They inhale and exhale through many pipes that are connected to holes (called spiracles) spread along the length of their bodies.
So, even without its head, a cockroach has little or no problem as far as its breathing is concerned.
How does a decapitated cockroach live without its brain and food?
A cockroach’s brain, as you can imagine, is not nearly as complex as ours. A roach brain consists of clumps of ganglia – nerve tissue agglomerations – that help it in performing the most basic sensory functions (like reacting to a flash of light, a touch etc.). A no-brain scenario, therefore, is not that big of an issue as far as sheer survival (in suitable conditions) for a few weeks is concerned.
As for the food, roaches are cold-blooded creatures, which means that unlike their hot-blooded counterparts (e.g., humans), they can last for days on a single meal they had on a good food-finding day. Moreover, in the absence of their head, they couldn’t possibly be very physically active, so their energy would be conserved too, helping them last for weeks without food.
In a nutshell, a cockroach can last weeks without its head, provided it’s not attacked by a virus, bacteria, mold or predators in that period and remains in a relatively cool environment.