Cockroaches are among the most enviable species in the world, thanks to their capability to endure some of the most deadly situations and come out just fine. For example, a cockroach has a higher resistance to radiation than human beings, (although contrary to popular myth, it can not survive a nuclear blast). It can also hold its breath for as long as 40 minutes, and it can last for weeks without food.
[caption id="attachment_2922" align="aligncenter" width="400"] Source - Twitter: @yaboiroachbug[/caption]
The most remarkable thing of all, a roach can survive without its brain! And not just for a minute or two, a decapitated cockroach can go on living for weeks and sometimes months on end!
Before we dive deeper into this mystery of roaches' headless survival, let's first examine why people (and nearly every animal on earth) cannot endure without their precious heads.
Why can't humans survive without their heads?
It's a well-known fact that human beings can not survive without their heads. There are quite a variety of anatomical factors behind this, but for the scope of this article, we will address just the ones that pertain to the case of headless roaches.
Firstly, decapitation leads to an extremely high amount of blood loss, which no human can make it through. This rapid bleeding would result in an inevitable drop in blood pressure, which implies that oxygen might not be carried to every part of the body, leading to death.
[caption id="attachment_2923" align="aligncenter" width="831"] The human "head" plays host to a variety of vital biological processes to sustain life.[/caption]
The nose, which is the chief facilitator of respiration in people, as it enables for inhalation and exhalation, is situated on our face, which is part of the head. Without the head, there would be no respiration, and therefore no opportunity for life to persist. Moreover, humans consume with their mouth, which is likewise located in the head. Obviously, that's another issue. Finally, since almost everything is controlled by the brain sitting at the top of the body, life for humans beings cannot be imagined without their head.
How can roaches endure without their heads?
Open circulatory system in cockroaches
To begin with, there's a significant distinction between humans and roaches relating to how blood flows throughout their particular bodies. The human body includes a complex circulatory system with a bunch of arteries, veins and various capillaries that crisscross inside the body to provide oxygen, in addition to crucial nutrients, for survival.
[caption id="attachment_2924" align="aligncenter" width="900"] A decapitation injury on a cockroach is quickly sealed off by clotting, preventing uncontrolled bleeding. Image Source: Nano Vina[/caption]
On the contrary, cockroaches have an 'open' circulatory system; it's rather primary and consists of just a little number of components. This avoids quick, unchecked blood loss following decapitation, as their necks are rapidly "sealed off" by clotting.
Respiration in cockroaches.
Unlike human beings, roaches do not need their mouths to inhale and exhale, as they do not rely on a single organ like we do, to serve that purpose. They breathe through lots of pipelines that are linked to holes (called spiracles) spread out along the length of their bodies.
[caption id="attachment_2925" align="aligncenter" width="810"] Even without its head, a cockroach has little or no problem as far as its breathing is concerned.[/caption]
How does a decapitated cockroach live without its brain and food?
A roach's brain, as you can think of, is not almost as complicated as ours. A cockroach's brain consists of clumps of ganglia — heaps of nerve tissues — that help it in performing the most fundamental sensory functions (like responding to touch, a flash of light, etc.). A no-brain situation, for that reason, is not that big of a concern as far as survival (in appropriate conditions) for a few weeks is concerned.
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When it comes to the food, roaches are cold-blooded animals, which indicates that unlike their hot-blooded equivalents (e.g., human beings), they can last for days on a single meal they had on an excellent food-finding day. Moreover, without their head, they could not potentially be extremely physically active, so their energy would be saved too, helping them last for weeks without food.
[caption id="attachment_2926" align="aligncenter" width="619"] Heads are so over-rated - Source: Jen Seng[/caption]
In a nutshell, a cockroach can last weeks without its head, supplied it's not attacked by an infection, mold, bacteria, or predators and remains in a relatively cold environment.
References:Cockroach on Wikipedia, Ganglion, Cockroach FAQ: Microbiology Department at UMass Amherst, Scientific American