Very often when we think about skin first thing that comes to mind is skin aging and wrinkles due to degradation of the collagen. Other example of wrinkles is when we keep our finger in water for too long. The outer layer of skin starts to absorb water and extends, resulting in a larger surface area and causing it to wrinkle.
Animal’s skin has often wrinkles or other features design for surviving in their natural environment. One of the examples is skin of shark, which has structure shaped like grooved and curved teeth with some cavities and has texture of sandpaper. The tooth-like structure is called dermal denticles or placoid scales. This structure enables sharks to swim faster and more efficiently because the friction of the water flowing along their body is reduced by channelling into grooves and cavities at their skin. Sharks can speed up to 50 km/h. Their skin has been already an inspiration for aerodynamic plains, cars and swimsuits. Additionally, the same surface protect sharks from adhering sea plants and organisms. It is one of the examples of self cleaning surfaces we can find in nature. The most known self cleaning surface is lotus leaf.
Picture of shark taken in the Oceanografic part of The City of Arts and Sciences in Valencia, Spain, October 2010.
The inspiration for protective clothing is for example crocodile skin, which is able to deflect spears, arrows, knifes and sometimes even bullets. The reason of the high strength of crocodile skin is not only the thickness but collagen proteins fibres. The collagen fibres are the reinforcement parts of skin scales. In similar way rugged crocodiles and sharks skins have cavities, but for crocodiles the cavities are used to push blood through the scales to absorb the heat. Interestingly, the examples of crocodile structure can be found in man-made material such as fibreglass, which is commonly used in automotive industry.
Pictures of crocodiles taken in the The Madras Crocodile Bank Trust in Chennai, Tamil Nadu, India, March 2008.
The evolution managed to come up with many more ingenious solutions. Researchers and engineers try to learn from the nature and biomimic some ideas but we need to keep in mind one thing that it was for nature very long creation process taking billions of years.
