Sharks aren’t just the bane of many Hollywood movies. These masterpieces of evolution have a fascinating skin structure; if you look closely (though maybe not too close!), their bodies are covered in dermal denticles, microscopic structures which overlay on top of each other to make up the shark’s skin. Though visually similar to scales, they actually have more in common with teeth and create a rough surface that reduce friction between skin and water. Being apex predators, sharks have to be able to swim quickly in short bursts. Thanks to lower friction drag, sharks and their rough coats can move faster in their aquatic environment, giving them an advantage over their prey.
Dermal denticles of the lemon shark, by Pascal Deynat (CC BY-SA 3.0).
Engineers are now coating aircraft with similar structures, mimicking dermal denticles to reduce drag. Just as denticles can reduce friction drag in sharks and help them swim faster, reducing drag in aviation can decrease resistance and save energy. This is also beneficial in reducing costs, as it lowers fuel consumption.
The roughness of shark skin also prevents algae and other microorganisms from attaching to it, which could adversely impact health and performance. This simple concept has applications in the medical industry; using materials with a similar structure in hospitals and other clinical settings can dissuade bacteria like E. coli from attaching to surfaces, preventing the spread of disease.
Another example of ocean biomimicry: a basking shark-inspired hydropower turbine. While some sharks feed on fish, molluscs and crustaceans, other species of sharks are more dentally challenged. Toothless basking sharks feed on zooplankton, gulping down gallons of seawater and filtering it out via their narrow gill slits. Water escapes via these slits, while the zooplankton stay trapped in the gills.
Basking shark off the Atlantic coast, by Florian Graner (CC BY 2.0).
Essentially, this is like a double converging nozzle, similar to a funnel. Water enters through a large opening, and then a second smaller opening, creating a pressure difference. The same principle is applied to the Strait Power turbine, where the pressure difference produces energy that can be used to power portable devices or home installations. This innovation is 40% more efficient than hydroelectric turbines that are currently in use.
This ‘biomimicry’ is driving progress in aviation, renewable energy, healthcare and beyond. So, if struggling to find solutions to an engineering or design challenge, perhaps looking to nature will turn the tide.