Fish and amphibians for example possess an organ, the lateral line, which is non-existent in land animals. With this sensory organ, which extends along the both sides of the body, they are able to perceive minute variations in pressure and current flow. As a result they are able, even in murky water, to form a very detailed picture of their immediate surroundings at a range of about the length of their body. They know where obstacles lie, where dangers lurk, and where their prey are to be found. Lateral lines are composed of hundreds or even thousands of fine sensory hairs that are located in tiny ducts beneath the skin and that register even tiny changes in flow velocity. The African clawed frog Xenopus laevis for example distinguishes between edible and inedible insects on the basis of water-borne vibrations. In terms of precision, these sensors are comparable with the human inner ear, where hundreds of thousands of fine sensory hairs enable us to distinguish between sounds -- from the sigh of the wind to a symphony.
However, the complicated part is not the sensor itself, but how the signals it sends are processed to create a complete picture of the surrounding area. Differences in pressure are much more difficult to accurately pin down than waves of light. We humans perceive the problem when a sound catches our attention and our eyes automatically seek out the source of the sound to confirm the location. Scorpions, on the other hand, use tiny vi
|Contact: Markus Bernards|
Technische Universitaet Muenchen