Smooth swimming

Sharks have amazing skin. Instead of rounded scales like you would find on a trout, sharks have thousands of tiny tooth-like scales called dermal denticles, a fancy way of saying “skin teeth.” Like teeth, they are hard, but on the outside they are covered with a softer material called collagen.

The design of these scales is different depending on where they are located on the shark’s body. What they all have in common, though, is tiny grooves that are close together, kind of like old records that your parents or grandparents played for music because there were no CDs or iPods.

All of these features are meant to let the shark glide through the water better, that’s why their skin feels soft if you run your hand along it from front to back, but rough as sandpaper if you rub it from back to front.

One shark is an odd fellow. The basking shark has scales going several different directions. According to the ReefQuest Centre for Shark Research, Norwegian fishermen, recognizing that a basking shark’s skin was not slippery, have long glued the fish’s skin to their boots to keep them from sliding around on the decks of wet boats.

Scientists have been fascinated by denticles because they help sharks move through the water very quickly and quietly. One maker of swimsuits tried to copy shark scales into the material they used, thinking it would help swimmers go faster in races.

Human scientists are having to play catch up, though, because sharks have been around about 400 million years, so they’ve had a lot of time to perfect their scale designs.

Some of the most recent research at Harvard University and the University of South Carolina has looked at putting denticle-like scales on planes, big wind generators’ blades, drones and even cars. The idea is that not only would the sharky features help these things move through the air more easily, they also could help with lift. Lift is the force that helps airplane wings lift big heavy jets off the ground.

It’s cool to think that sharks may help airplanes fly.

— Brett French, french@billingsgazette.com

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