Touch and vibration
The sense of touch is often referred to as the mother of all sensory systems. It is an ancient sense in evolution: even the simplest single-celled organisms can feel when something brushes up against them and will respond by nudging closer or pulling away. While the other senses are located only in specific parts of your body (taste, smell, sight, hearing), for humans and many other species, the sense of touch is located throughout. Humans have touch receptors covering nearly every inch of the body. These nerve endings can sense pain, temperature, texture, and pressure. Animals have evolved to have a more heightened sense of touch than their simple-structured ancestors. Existence would be very difficult, and in most cases, nearly impossible without the sense of touch and vibration.
Comparative anatomy - the best of the best
Best earthquake detector -
|
Best Whiskers - The sealA cat’s whiskers are incredibly sensitive and help it judge size and distance incredibly accurately. But a seal’s whiskers possess more nerve receptors per hair, which are perhaps the most finely tuned whiskers in the animal kingdom. Using them, seals can track fish swimming 180 meters (591feet) away in even the murkiest of water. Blindfolded seals can track passing miniature submarines from 130 feet away by using their extraordinarily sensitive whiskers to follow the wakes the mini-subs leave behind in the water.
Most sensitive nose - The star nosed moleThis nearly-blind creature’s unique nose has almost six times the amount of touch receptors than a human hand. It's nose is primarily used for feeling, not smelling. As it makes its way down a tunnel, it sweeps its 22 fleshy tentacles back and forth with incredible speed, touching 10-12 different objects per second. And as soon as a tasty worm is detected, it’s eaten within milliseconds.
http://videos.howstuffworks.com/health/sense-of-touch-videos-playlist.htm#video-32967 |
That's pretty neat!
Scientists have determined that the human finger is so sensitive it can detect a surface bump just one micron high - 1/400,000th of an inch — the diameter of a bacterial cell — and our fastidious fingers can find it! The human eye, by contrast, can't resolve anything much smaller than 100 microns.