Selected portions of the article here.....
Twenty-six baby fish are now orbiting Earth aboard an unmanned Russian spacecraft, in a long-delayed experiment that researchers hope will lead to a better understanding of inner-ear balance mechanisms in humans.
Reinhard Hilbig and Ralf Anken, neuro- and developmental biologists at the University of Hohenheim in Germany, will monitor the larval fish to watch the growth of their otoliths — sensory organs that have a role in hearing and balance — in microgravity conditions during the 12-day mission.
Otoliths, also found in the inner ear of humans, are sensitive to gravity and linear acceleration and are essential for maintaining proper balance. They are composed of a mix of gelatinous material and calcium carbonate, which shift around in a viscous fluid when the head moves, stimulating hair cells and conveying information about movement to the brain.
Scientists think a misfunctioning otolith is the culprit for conditions such as Ménière's disease, which causes vertigo and 'ringing in the ears' in sufferers. But they do not yet understand exactly how this organ works. The otoliths of fish provide a good candidate for study, says Hilbig, because they function in exactly the same way as human ones but are considerably larger. This is because fish must orient themselves underwater, where other motion clues are suppressed.
Quite interesting stuff....

