Though better known for their rows of flesh-tearing teeth, sharks' extraordinarily thick skins may be as impressive. Their skin is also coarse in texture, making it impossible for any animals, bacteria, or algae to latch on--unlike, say, a whale, whose skin acts as a magnet for a variety of hitchhikers.

This rugosity made the shark's skin an attractive model for Sharklet Technologies, a Florida-based startup, which has made an antibacterial film based on its design. The film, which is covered with millions of tiny, raised bars arranged as adjacent diamonds, can be applied as an adhesive to surfaces like doors and containers to prevent the growth of bacteria. Created with an eye on hospitals, the company's scientists claim that the films can hold off the formation of bacterial colonies for up to 21 days. Because the films do not actually kill the colonies, there is little risk of the bacteria developing a resistance to them--a major downside to the use of antibiotics.