This Is What Shark Skin Really Feels Like

Who hasn't wanted to pet a shark? They might be apex predators, but they're still pretty cute. While they look featureless upon first glance, their skin is actually composed of dermal denticles. Dermal refers to skin, and the word denticle alludes to small teeth, so another way to describe their texture would essentially be "skin teeth." These are scaly triangles coated in dentine, which is the same type of tissue that composes the majority of a mammalian tooth. That might not sound very pleasant, but the directionality of these scaly teeth means that if you theoretically were to pet along the grain, their skin would actually feel relatively smooth.

Of course, there are evolutionary benefits to this type of skin. First, the structure allows sharks to swim faster. The way that these denticles are patterned reduces resistance in the water. There are high ridges in the middle and low ridges on the sides, which researchers modeled to discover that such a formation in white sharks reduces drag by 2.3 meters (7.5 feet) per second. Great white sharks often cruise through ocean waters at a speed of 3 to 4 kilometers per hour, which translates to roughly 1.9 to 2.5 miles per hour. Although this is pretty fast, it is leisurely compared to the pace they can reach in short bursts of 55 kilometers (or 34.2 miles) per hour. For reference, the Olympic swimmer, Caleb Dressel, broke records, reaching at least 8.8 miles per hour.

In addition to these high speeds, sharks often swim long distances. A great white shark was observed taking a journey of 12,400 miles. The reduction in calculated drag force maintained by their skin allows them to swim more efficiently, conserving energy and making it possible for them to travel so far. Some researchers have noticed that the unique patterning of the ridges within their denticles likely optimizes conditions for various types of swimming, whether cruising or accelerating to catch prey.

Another aspect that makes them such impressive hunters is that the reduction of friction facilitated by their skin allows them to swim both quickly and quietly. Although recent research has revealed that some sharks generate a clicking sound, particularly when in distress, for the most part, they are known as silent predators, swimming underwater in an unnerving quiet. This advantage in sneaking up on prey adds another layer to their fantastic hunting capabilities.

Not only do these dermal denticles make for effective predation, but they also protect sharks. The unique texture that lines their bodies makes it difficult for anything to really latch on. This means special protection against barnacles and other types of marine growth, as well as parasites. Additionally, this thick, rough skin shields them against abrasions that could otherwise occur through contact with rough surfaces or conflict with other animals.

A short explanation that is typically offered to explain the sensation of touching a shark is that it feels like sandpaper. Although sharks are certainly not as dangerous to humans as Steven Spielberg might have led us to believe, even touching a shark could lead to injuries. Those dermal denticles are actually somewhat sharp, and contact can leave cuts in your own skin. After all, we don't possess that outward layer of protection that sharks have.

While humans should avoid sharks, simply in an effort not to disturb their habitat or risk provoking them, the understanding of shark skin gained through research has led to many innovations. Using the natural state of something as a guide for manufacturing is known as biomimicry, and copying sharks has been pretty successful.

For example, a swimsuit brand based its design on the shark's dermal denticles. As discussed earlier, their structure is effective at reducing drag, which allows for greater speed. In fact, this particular swimsuit provided such an advantage that it was banned from Olympic competitions.

However, not all shark-inspired inventions have been solely purposed for speed. Biotechnology companies have introduced material based on the sand-papery skin due to its ability to inhibit parasitic growth. Certain products have been tested on surfaces within the hospital and shown to effectively reduce bacterial growth. Such an achievement is one of many examples of how understanding basic science can lead to innovation and improvements in health.