zoology biology benno meyer rochow science blog death halloween Florian Nock

Science & Halloween : Death

An inevitable part of life’s programme

Only the most primitive organisms, the so-called single cell “animals”, i.e., the protozoans -and not even all of them- are potentially without death as they grow, divide, separate and repeat this cycle over and over again. Normal cells of mammalian tissues in isolated cultures will also continue to “live” and divide, sometimes long after the host’s body they originated from has succumbed. The difference to the protozoan life forms, however, is that these mammalian cells eventually appear to run out of divisions. It is as if death was programmed into their genetic code through the gradual shortening of so-called telomeres present at the ends of the chromosomes. Human cells can divide, and divide, and divide again, perhaps fifty times or a little more, and then they come to the end of the road, so-to-speak. Although human skin cells will be viable for up to a couple of days after a person has died, the often heard opinion that fingernails and body hair continue to grow after death is an illusion brought about by the fact that a dead body loses water and actually shrinks. Thus, the harder structures like fingernails and hair become more prominent and appear to grow. —>

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Danger in Disguise

When animals aren’t what they seem

I had a dramatic and painful introduction to “mimicry” as a little boy, when my Auntie Alice from Chislehurst in England had come over and I was eager to teach her what I had learned from my grandfather. We looked at the flowers in the Botanical Garden and she warned me of the many bees. Now came my time, I thought, and I told her that they weren’t really bees; that they only looked like bees and that in reality they were a kind of harmless fly. To prove my point -and to be a hero, I guess- I caught one like I had seen my grandfather do it……. and was promptly stung! —>

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Re-growing a Lost Leg

No problem (if you are a newt)

When in 1987 I applied to obtain research funds to continue a project on spinal cord regeneration that I had started with Dr Alibardi from Italy, I was unsuccessful. However, the question of spinal cord regeneration is still a compelling one. Mammals and birds are poor regenerators and usually cannot replace lost or malfunctioning parts of the central nervous system, but in lower vertebrates and many invertebrates the situation is different. Starfish, as most people would know, have no problem re-growing severed arms, but they aren’t vertebrate animals. Among the vertebrates most lizards can at least replace a lost tail, but in newts (my favourite animals) and salamanders the ability to replace lost or injured body parts is even more remarkable and goes much further. —>