If a cockroach is beheaded will it continue living until it starves to death?

Answer 1

Insects, cockroaches included, have a nervous system that is made up of a series of ganglia (bundles of neurons) all along the ventral nerve cord. Some are located in the abdomen, which innervate the genitalia, sensory structures like the cerci, and some organs; some ganglia are located in the thorax, which innervate muscles for the legs & wings; then there is the brain, which is located in the head, and is likewise nothing more than a series of fused ganglia and is responsible for processing sensory input from the antennae & eyes among other things. All of these ganglia running down the nerve cord through the body act as mini-brains & because each has separate functions, the removal of one or a few (such as what happens when the head is removed) only has the effect of limiting those functions that its tied to. So, a cockroach can live without its head because it still has the mini-brains in the rest of the body allowing it to still crawl around and the organs to function. The cockroach usually dies as a result of dehydration rather than as a direct result of the decapitation (because it can no longer drink water without its mouth parts located on the head...death by dehydration is much faster than death by starvation).