Nature’s Answers to Self-Cleaning and Fluid Dynamics

In 1975 the movie “Jaws” was widely regarded as one of the best horror-thriller movies of its’ time. It certainly scored high on the fear factor as many people would not swim in an ocean without looking carefully over the surface for that dreaded fin coming toward them. For years I caught myself looking for it even when in fresh water lakes. Yes, it’s embarrassing to admit it, but it sure speaks to the power of the film.

Well, it seems that sharks got a bad rap after that because many people viewed them as frightening, man-eating creatures when, in fact, most of them are harmless. Not only are they fascinating because of their keen sense of smell and greatest electrical sensitivity of any animal on this earth, but they are also another example of an innovation in self-cleaning and fluid dynamics.

Sharks apparently move through the water very quickly and efficiently because of their natural skin design. Their skin has many small individual ribbed scales called dermal denticles (known as “little skin teeth”). This helps with their fluid dynamics because seawater has lots of algae, bacteria and barnacle larvae in it, known as ecto-parasites, that slow down movement through it. These dermal scales continually flex in response to changes in pressure associated with the shark’s movement. Not only does this reduce the available surface area for anything to adhere to it, but it also serves to reinforce the direction of water flow by accelerating it at the skin’s surface. This, in turn, effectively minimizes the contact time of the ecto-parasites that cause friction drag.

All of this is of great interest to boat manufacturers because the ecto-parasites that attach to a ship’s hull are major sources of energy inefficiency. Similar to the lotus plant inspired resin, there are now surface coatings inspired by shark skin that show a 67% decrease in organism attachments, a sure speed booster, and they are completely self-cleaning at 4-5 knots.

Another lesson from nature that produces no waste, no pollution and is energy enhancing. So while we may not be drawn to sharks in the same way as we are to cuddly kittens, we can appreciate and respect them for their value in nature.

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