This vicious-looking sunnovabitch here just lost a fight against the sharp end of a shovel—but you think that lack of a body is going to slow him down? Not a chance. Turns out, a wide range of predatory snakes are capable of reacting to stimuli and lashing out at potential threats for up to an hour after being relieved of the rest of their mortal coils.
In warm-blooded animals, our high metabolisms are a significant disadvantage when being decapitated. Just a few minutes without oxygen and a mammal's brain is caput—the result of a massive cascading cellular die-off. Not so with cold-blooded reptiles. Their slow metabolism sustains their internal organs for far longer than a mammals causing them to completely die far more slowly. Essentially, cutting off their heads only makes them mostly dead.
As Clifford Warwick discusses in his 1990 book Reptiles: Misunderstood, Mistreated and Mass-Marketed, while the body's writhing motion is a reflexive action—much like that of a lizard's detached tail—the head itself will live on for a while. Likely in excruciating pain:
Some of the many ways in which reptiles are "killed" are mentioned later on but one method which is quite commonly used is decapitation. Generally speaking, in mammals and birds, for example, quickly severing the head from the rest of the body may cause immediate or near immediate loss of consciousness and a very rapid death. It might not be describable as 'humane' but the period of post-severance life in the head is almost certainly short.
Although meaning certain death, decapitation is certainly not a rapid or humane way of killing reptiles. As hard to believe as it seems, the heads cut from reptiles live on well after the horrific event of decapitation itself. It is not a case of "nerves causing the head to move unconsciously" as most people think. The heads, and parts of the neck if still attached, are alive and some may attempt to bite objects which approach; the eyes may follow movement and the pupils contract and dilate in response to light and dark; they can blink and in the case of snakes and lizards, flick out and in their tongues to test the air for scent and even move slightly if enough of their neck is left.
With what movement they can manage they often writhe in agony from the massive severance of tissue. They are virtually helpless, frightened and going to die. If it seems too inconceivable to be true, then think of it as being a case of animals which have had most of their bodies cut away. One might think that suffering of this kind could not be endured for long. If only that were true. Unfortunately, a problem associated with the reptilian metabolism's ability to operate at relatively low oxygen and low blood pressure levels is that nerve tissue is, to put it simply, very tough. Therefore, the nervous system, which of course includes the brain, can function away from the rest of the body for some time. In fact, the activities of decapitated heads mentioned earlier have been recorded as present for around an hour or so. If reptiles are to be killed by physical means (rather than by, say, an injected overdose of an anesthetic), then it has to involve complete and rapid destruction of the brain; otherwise they are very likely to suffer enormously and for a long time before dying.
And in their time of dying, snakes are just as deadly as when they were whole, often extracting their final revenge against their aggressors—most recently in China's Guongdong province. In that region, Indochinese spitting cobra is a popular ingredient in a local specialty, diced snake soup. Chef Peng Fan died last weekend while preparing the dish, after being bitten by a 20-minute old severed head. He died en route to an area hospital.
So remember, if you find a snake in your yard—especially a venomous one—stay out of its way and call animal control. Don't be an asshole and just kill it. Or if you do feel the need to to end its life for briefly inconveniencing yours, at least have the courtesy to brain the poor beast with a mallet rather than let it suffer 60 minutes without a body. [TreeHugger - i09 - NatGeo - Anapsid - NZ Herald]