page_title: Fish scale
section_title: Technical application
hierarchical_section_title: Fish scale / Placoid scales / Technical application
caption_attribution_description: Barbette Saltmarsh boats, plants, stilts
context_page_description: A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as well as possible hydrodynamic advantages. The term scale derives from the Old French "escale", meaning a shell pod or husk.
  Scales vary enormously in size, shape, structure, and extent, ranging from strong and rigid armour plates in fishes such as shrimpfishes and boxfishes, to microscopic or absent in fishes such as eels and anglerfishes. The morphology of a scale can be used to identify the species of fish it came from.
  Most bony fishes are covered with the cycloid scales of salmon and carp, or the ctenoid scales of perch, or the ganoid scales of sturgeons and gars. Cartilaginous fishes are covered with placoid scales. Some species are covered instead by scutes, and others have no outer covering on part or all of the skin.
  Fish scales are part of the fish's integumentary system, and are produced from the mesoderm layer of the dermis, which distinguishes them from reptile scales.
context_section_description: In the marine industry, there is an extremely large market and need for anti-fouling surfaces. In laymen's terms, fouling is known as the process by which something becomes encrusted with material from the surrounding environment such as the following: barnacles, algae, and green sludge. Dermal denticles are an extremely promising area of research for this type of application due to the fact that sharks are one of the only fish without build up or growth on their scales. Studies by the U.S. Navy have shown that if a biomimetic material can be engineered, it could potentially cause an increase of fuel savings in military vessels up to 45%.
  There are many examples of biomimetic materials and surfaces based on the structure of aquatic organisms, including sharks. Such applications intend to enable more efficient movement through fluid mediums such as air, water and oil.
  Surfaces that mimic the skin of sharks have also been used  in order to keep microorganisms and algae from coating the hulls of submarines and ships. One variety is traded as "sharklet".
  A lot of the new methods for replicating shark skin involve the use of polydimethylsiloxane (PDMS) for creating a mold. Usually the process involves taking a flat piece of shark skin, covering it with the PDMS to form a mold and pouring PDMS into that mold again to get a shark skin replica. This method has been used to create a biomimetic surface which has superhydrophobic properties, exhibiting the lotus effect. One study found that these biomimetic surfaces reduced drag by up to 9%, while with flapping motion drag reduction reached 12.3%.
  Along with marine applications, the aerospace industry can also benefit from these biomimetic designs. Parametric modeling has been done on shark denticles with a wide range of design variations such as low and high-profile vortex generators. These biomimetic models were designed and analyzed to see the effects of applying the denticle-like structures to the wings of various airplanes. During the simulation, it was noted that the sample altered how the low and high angles of attack reacted. Out of both the low and high-profile samples tested, the low profile vortex generators outperformed the current smooth wing structures by 323%. This increase in performance is due to a separation bubble in the denticles wake and stream-wise vortices that replenish momentum lost in the boundary layer due to skin friction.
caption: Barnacle Growth on Boat Hull
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