Training yourself to see underwater

Not as far-fetched as it might sound, as this article from the Independent reports (spotted thanks to the ever-informative Medpundit):

Ordinarily, human eyesight becomes blurry under water because the eye is structured to see through air. But the Moken nomads, who tie stones to their waists so they submerge long enough to forage for seafood, can constrict their pupils to pin-prick size and spot pearls measuring only 1.5mm in diameter. They also squint in order to squeeze the lenses of their eyes, which temporarily thickens them and improves focus under water.

"They use the optics of the eye to the limits of what is humanly possible," said Anna Gislen, a Swedish biologist who led the study. At best, the sharpest-eyed children could distinguish objects that measured 3mm across.

Young [European] snorkellers volunteered to toss aside their masks and be tested at the tourist islands of Ko Samui, Ko Phi Phi and Ko Poda. None of them could constrict their pupils at will, as the Moken did routinely on every dive. . .

An estimated 5,000 Moken nomads roam the archipelago between western Thailand and Burma on bamboo houseboats, gathering edible sea slugs and fish while competing with crab-eating macaques for delicacies in tidal pools.

Once this story gets out, I wonder how many divers will be spending hours in front of the mirror, trying to teach themselves how to constrict their irises at will?

Posted by David on May 26, 2003 10:26 AM