zoology biology benno meyer rochow science blog smell taste dogs odours Florian Nock

Smell : Potential Burglars Beware of dogs !

Dogs are after you !

Although most humans have a relatively big nose right in the centre of their face, that organ’s main function seem to be there to support the spectacles and to pre-warm the air that enters the nostrils. Our sense of smell isn’t exactly great when it comes to a showdown with other nose-possessing organisms, but when I use the plural “we”, I am not exactly accurate, for female noses consistently outperform those of males and there are even odours that men and children cannot but mature women can smell. There is also the aspect that in women odour thresholds vary over the menstrual cycle. Generally speaking, however, we humans aren’t smell champions and find it hard to understand how a police dog can follow the track of a wrongdoer or a lost person, how salmons sniff out their home rivers on their migrations to their birth stream, how ants smell odour trails laid down by worker ants and how male moths can possibly detect the scent of a female 10 km away.

zoology biology benno meyer rochow science blog moving in water Florian Nock

Moving in water : Screwing up (and down of course)

And spiralling around as well

A look at the diminutive, fantastically diverse life forms and their activity in a single drop of water can be a truly amazing experience – provided of course you have not chosen tap or rainwater. A drop of water from the edge of a weedy pond (or a puddle near a penguin rookery, which was my source for a study) examined under a simple light microscope does, however, reveal a microcosm of hidden life. In amongst the jittering soup of miniature plants and animals, it is the group of ciliated protozoans that are the greatest attention getters. The smallest may not even reach 50 microns, while Paramaecium and Euplotes maximally attain 1 mm and the biggest like Spirostomum may reach a length of 3-4 mm.

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. —>