Honed to hunting perfection by millions of years of evolution, there's a lot we can learn from sharks. More than just "Stay out of the water", "Keep the hell away from Amity Island" and how to play the cello. Their skin is a nanostructured surface perfected for their role as nature's flesh-seeking missile, and while human swimmers and boats aren't generally blood-motivated murderizers they can benefit from the same coating.
Synthetic shark skin might sound like the ultimate in faux-fashion
disasters, but work at the University of Florida by materials engineer
Tony Brennan and colleagues has allowed us to coat boats and even
Olympic swimmers in this material. It turns out that shark skin is not
smooth, but consists of thousands of "dermal denticles" and yes, that
means "denticle" as in "dentistry and teeth". Not content with going
through up to thirty thousand actual teeth in its lifetime, sharks are
actually coated in adapted versions of the things - meaning it
maintains its speed advantage literally by the skin of its teeth.
These scales have small-scale structure, a series of grooved channels
which move slightly as the scales turn and flex with the shark's
motion. It turns out that the smoothest possible surface won't
increase your speed in the water - the layer of fluid right next to the
smooth surface will be slowed down by friction, and as that water drags
against the faster water further away turbulent vortices are created,
every one of them slowing the submerged object down. The mini-ridges
in the shark scales channel the water into faster flow, as well as
mixing the slower and faster faster flows in a less turbulent manner.
This involves hydrodynamics which takes a degree and some high-level
simulation software to calculate, but a few million generations of
sharks seem to worked out the hard way.
These coatings have been used in Speedo Fastskin swimsuits and boat
hulls. You might associate Speedo with not wearing very much at all,
but the FastSkin suit actually does cover a lot of flesh, and has
conferred significant advantages on those who do so - wearers won 80%
of all medals and broke 13 (of 15!) world records in the 2000
. Speedo have upgraded their shark-simulating skin, so expect
to see even better performances (but hopefully no feeding frenzies) in
Beijing this year.
Posted by Luke McKinney.
Related Galaxy posts:
Cetacea: Mind-Bending Theories About the Planet's "Other" Intelligent Life
The Planet's Other "Intelligent" Species: Do Dolphins Have a Sense of the Future?
Australian Scientists Begin to Crack Whale Code
Source links:
Biomimicking Sharks
Shark skin research
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