Robert Kim
WRIT 340 – Prof. Ramsey
Shark Skin: Inspiration for Modern Scientific Advancements
Introduction
In contrast to the science fiction films that often act as the inspiration for scientific
breakthroughs, some engineers have created state of the art technologies with inspiration from
nature. Just by living and reproducing, animals that have evolved over millions of years are
doing what engineers and other scientific professionals strive to do: optimizing and refining
themselves. One prime example of an optimized animal is the shark. Sharks have been around
for over 400 million years which means they have had a lot of time to adapt to their
environments [1]. Often regarded as cold-blooded, efficient killers, it might not be immediately
evident that sharks have the potential to help humans in many ways. Although their prowess as
predators is indeed very impressive, scientists and engineers are more interested in a part of
sharks that is much less obvious: their skin.
Science of Shark Skin
Shark skin has several interesting properties that prompt engineers to try to understand
and replicate it. Those properties include: drag reduction, barnacle and algae growth prevention,
and providing a tough exterior for protection [2]. It is able to do all of this due to its very unique
physical structure. Shark skin is comprised of millions of placoid scales called denticles (Fig. 1).
Robert Kim
WRIT 340 – Prof. Ramsey
Figure 1. 650X magnification of skin of great white shark. Source: Ocean Portal
The outer layer of a denticle is made of vitrodentine, a hard, enamel-like substance, while the
inside consists of a central pulp cavity [3]. The combination of the hard outer layer and softer
inner portion results in a building block that is not only strong, but also resistant to cracking [4].
These microscopic denticles cover the entirety of a shark’s body and are arranged in overlapping
layers that allow the shark to still move freely. Each denticle has ridges that run parallel to the
flow of water. It is the shape of the denticles that are responsible for minimizing drag and
preventing the growth of barnacle and algae on sharks.
Drag on smooth surfaces is caused by fluid flowing slower at the surface than further
away [2]. This difference in speed between the layers of flowing fluid will result in turbulence
that inhibits the motion of the object through the fluid. Shark skin overcomes this problem with
the special grooves in its denticles. The grooves force the water into smaller channels, so the
water has to speed up. This results in a smaller difference in water speeds, and therefore, less
Robert Kim
WRIT 340 – Prof. Ramsey
turbulence and less drag (as much as an 8 percent difference) [3]. These characteristic grooves
prevent eddies from getting to the surface of the shark [5]. In fact, a study by George Lauder and
Johannes Oeffner suggests that shark skin not only reduces drag, but even produces thrust [6].
There a several reasons why barnacles and algae have such a hard time sticking to sharks,
and they also stem from the shape of the scales. The accelerated water flow that is resultant from
the grooved shape not only helps to reduce drag, but also give less time for barnacles and other
hitchhiking sea dwellers to adhere themselves to the skin of the shark. The grooved texture of the
denticles also reduces the available surface area that aquatic organisms can grab onto [2]. Lastly,
the flexible configuration the denticles means that they are always moving in relation to one
another, creating an ever moving target [1].
Current Applications
The dynamic range of advantages that sharks get from their skin obvious, and it turns out
that there are a plethora of applications for technology inspired by shark skin. The most obvious
are applications that also are at home in water. Sharks need to swim quickly for hunting and
survival, but humans also want to swim quickly for sport. To maximize the speed at which a
swimmer can travel, reducing drag is imperative. This is why materials that replicate the nanotexture of shark skin has been developed for use in swimsuits [2].
Drag reduction is useful for other more industrial applications as well. Ships have long
been plagued by barnacles and algae that grow on their hulls (Fig. 2).
Robert Kim
WRIT 340 – Prof. Ramsey
Figure 2. Barnacles on the hull of a ship. Source: Earth Times
By using a coating that mimics the properties of shark skin, a ship can reduce the amount of
growth on their hulls and actually clean themselves when they begin to move at speed [3]. By
reducing the weight and also the drag acting upon a ship, it will be able to travel further on a
smaller amount of energy, thereby using less fuel. In addition to the added efficiency of ships
with coatings inspired by shark skin, there are positive environmental impacts as well.
Traditionally, paints with harsh biocides have been used to prevent unwanted growth on
the hulls of ships. However, the effects of these chemicals could not be isolated, and as a result,
impacted other species in the area [7] So, by discontinuing the use of such biocides and instead
using shark skin inspired coatings to prevent unwanted growth, other aquatic species are spared
from the harmful effects of biocides. The utilization of shark skin inspired coatings touts another
environmental benefit. Barnacles and other types of freeloading life forms from one part of the
world can potentially become invasive species elsewhere. By preventing their growth and
Robert Kim
WRIT 340 – Prof. Ramsey
transportation on ships, their potential to become invasive species and disrupt other ecosystems
is also eliminated [2].
The characteristics of shark skin that make it difficult for aquatic organisms to attach
themselves to the hulls of ships can also be used in dry environments, namely in hospitals and
other healthcare settings. Materials with surface structures similar to the grooves in the denticles
of shark skin have proven to prevent the growth of bacteria [8]. From research conducted at
Sharklet technologies, it works because it is thought that microorganisms have to exert more
energy to colonize a rough surface [8]. This is has the immediate benefit of decreasing the
amount of potential illness causing microorganisms, thereby decreasing the likelihood of
someone contracting a disease. The long term and perhaps most important benefit of shark skininspired materials in the health field is that it also does not encourage the bacteria to build up
resistance [9]. This is in contrast to conventional antibiotics which become less and less effective
at combating diseases as harmful bacteria adapt to resist them, effectively creating bacteria that
are immune to certain antibiotics.
Other Potential Applications
It is clear that technologies based upon shark skin can be applied in diverse fields, but its
applications have not been fully realized. Shark skin is a prime example of nature evolving to
maximize efficiency. Fortunately, areas where we can try to mimic shark skin to maximize
efficiency are numerous. Most do not notice it, but even our “dry” world is actually completely
submerged in the fluid known as air. Drag is present when any object moves through a fluid,
which means that the drag reducing properties of the denticles can be applied to nearly anything
that we want to make move more quickly and efficiently.
Robert Kim
WRIT 340 – Prof. Ramsey
Coatings that would mimic the nano-texture of denticles could be applied not only to
ships, but to other forms of transportation such as cars and bullet trains. Just like in the case of
ships, cars and trains that use a shark skin mimicking coating would immediately reduce their
fuel consumption. Less fuel used means cheaper operation costs, which would also allow for
cheaper transportation for consumers. Since energy has become such a scarce and valuable
commodity, it has also become important to conserve it where possible. This conservation of
fuel, in addition to its cost-saving benefits, will also help the environment. In the case of vehicles
that depend on fossil fuels, the reduction in the amount of fuel being combusted will result in a
decrease in CO2 emissions, which can contribute to the greenhouse effect. Overall, the
widespread use of shark skin-inspired coatings in means of transportation ranging from ships to
automobiles and trains would add up to huge benefits in terms of both financial savings and
minimizing environmental impact.
The drag reduction provided by the nano-texture of shark skin coatings could also be
helpful when used in pipelines. Although the benefits of drag reduction in the plumbing of most
houses and buildings would probably be negligible, that would not be the case for longer pipes.
For example, the Trans-Alaska Pipeline is used to transport oil 800 miles [10]. If drag on its
inside walls could be reduced, the pipeline pumps would not have to work as hard, and thus, use
less energy. Furthermore, the coating would be able to resist the adhesion of various unwanted
substances in the pipes and would help prevent blockages. Preventing such blockages would
allow for continuous production and transport of the oil, creating a more profitable system.
Unlike the reduction of drag, this resistance to blockages would be useful in all pipeline systems,
ranging from the huge scale of the Trans-Alaska Pipeline to the plumbing of a house.
Robert Kim
WRIT 340 – Prof. Ramsey
Conclusion
By mimicking the intricate structure of shark skin, there are far reaching impacts ranging
from decreasing fuel consumption in large ships, to preventing the spread of harmful bacteria in
hospital environments. While something like shark skin at first seems unremarkable, the
numerous applications of technologies inspired by shark skin seem to indicate that nature is
likely a fertile breeding ground of inspiration for the noteworthy technologies of tomorrow.
Robert Kim
WRIT 340 – Prof. Ramsey
References
[1] Shark Basics [Online]. Available:
http://www.flmnh.ufl.edu/fish/education/questions/basics.html
[2] Biomimicking Sharks [Online]. Available: http://biomimicryinstitute.org/home-pagecontent/home-page-content/biomimicking-sharks.html
[3] (2005, May 1). Materials Engineers Turn to Ferocious Fish for Nonstick Ship Coating
[Online]. Available: http://www.sciencedaily.com/videos/2005/0505sharkinspired_boat_surface.htm
[4] (2005, May 1). Materials Engineers Turn to Ferocious Fish for Nonstick Ship Coating
[Online]. Available: http://www.sciencedaily.com/videos/2005/0505sharkinspired_boat_surface.htm
[5] Skin of the Teeth [Online]. Available: http://www.elasmoresearch.org/education/white_shark/scales.htm
[6] K. Knight (2012, March 1). Shark Skin Produces Propulsion [Online]. Available:
http://jeb.biologists.org/content/215/5/i.1.full
[7] The potential effects of antifouling paints [Online]. Available:
http://www.ukmarinesac.org.uk/activities/recreation/r03_03.htm
[8] A. Cooper (2009, October 29). A Material Based on Sharkskin Stops Bacterial Breakouts
[Online]. Available: http://www.popsci.com/science/article/2009-10/saving-skin
[9] K. Herzog (2013, March 5). Health officials warn of 'nightmare bacteria' in hospitals
[Online]. Available: http://www.jsonline.com/news/health/health-officials-warn-of-nightmarebacteria-in-hospitals-qt91kr5-195476791.html
[10] Pipeline Facts [Online]. Available: http://www.alyeska-pipe.com/taps/pipelinefacts