No Head Equals Dead?

We can't live without our head. Common sense isn't it?

First off, the blood supply to our brain will be cut off. After six minutes without oxygen, our brain begins to die.

Secondly, we breathe through our mouth and nose, and decapitation stops that input of air. No oxygen goes into our system and hence other vital organs will start to die.

Thirdly, without a mouth to eat, the body basically starves to death.
But there is an exception--a cockroach can live up to several weeks without its head.

How do they do it?

Cockroaches do not have blood pressure the way people do. In fact, they have an open circulatory system with less pressure. So unlike us, they won't bleed to death. Very often when a cockroach's head is cut off, the neck would seal off just by clotting.

Moreover, they can breathe through spiracles on their body, so breathing through nose is optional. The spiracles pipe air directly to tissues through trachea. And like all insects, cockroaches are cold-blooded, i.e. they do not need much food like mammals or birds. A cold-blooded reptile, for example, needs only a meal per week, and some crocodiles even go a year without food.

Insects have clumps of ganglia--nerve tissue agglomerations--distributed without each body segment capable of performing the basic nervous functions responsible for reflexes. So, the headless body can still stand, react to touch, and move.

Even the severed head can survive decapitation, waving its antennae for several hours until it runs out of steam. If given nutrients and refrigerated, the severed head can last even longer.

There is a niche, however, in their amazing ability to survive decapitation. The insect, which is well-known for its awesome memory, doesn't perform well after decapitation. The head, it seems, needs a constant influx of sensory information from the body in order to function well.

Still, surviving decapitation is an amazing ability. Marvel should consider creating a superhero based on roaches. It'd be super cool.

Malcolm

info: http://www.scientificamerican.com/article.cfm?id=fact-or-fiction-cockroach-can-live-without-head