Featured Research

from universities, journals, and other organizations

Sharks Provide Key Insight For New, Non-toxic Anti-algae Coating

Date:
March 15, 2005
Source:
University Of Florida
Summary:
University of Florida engineers have developed an environmentally friendly coating for hulls of ocean-going ships based on an unlikely source of inspiration: the shark.

UF materials engineers have tapped elements of sharks’ unique scales to develop an environmentally friendly coating for hulls of ocean-going ships that prevents the growth of an aggressive marine algae and may also impede barnacles. The coating is composed of billions of tiny raised diamond-shaped patterns, each measuring about 15 microns, or 15 millionths of a meter, considerably smaller than the 80- to 200-micron diameter of a typical human hair. In the latest version of the coating, the ribs in each pattern swell and shrink in response to an electric current -- in effect flexing in and out from a ship's hull surface. That may be useful because the movement could prevent the accumulation of silt and other debris on the hulls, often a precursor to plant and barnacle growth.
Credit: Photo by: James Schumacher/Major Analytical Research Center

GAINESVILLE, Fla. --- University of Florida engineers have developed an environmentally friendly coating for hulls of ocean-going ships based on an unlikely source of inspiration: the shark.

UF materials engineers tapped elements of sharks’ unique scales to design the new coating, which prevents the growth of a notoriously aggressive marine algae and may also impede barnacles, according to preliminary tests.

If more extensive testing and development bear out the results, the shark-inspired coating -- composed of tiny scale-like elements that can actually flex in and out to impede growth -- could replace conventional antifouling coatings. These coatings prevent marine growth but also leach poisonous copper into the ocean.

“The copper paints are wonderful in terms of keeping the ship surface clean, but they are poisonous and they accumulate at substantial rates in harbors,” threatening marine life, said Anthony Brennan, a UF professor of materials science and engineering and the lead developer of the coating. “By contrast, there are no toxins associated with our surface.”

Brennan’s project is being sponsored by the U.S. Navy, the world’s largest maritime ship owner, which has contributed at least $750,000 to the effort so far.

According to the Navy, algae and barnacles on hulls increase drag, slowing ships and reducing fuel efficiency. Of the $550 million to $600 million the Navy spends annually on powering its ships and submarines, at least $50 million stems directly from fouling-related increased drag, said Stephen McElvany, a program officer in environmental quality in the Navy’s physical science division. The Navy hopes to find both a more effective and environmentally friendly technology than the copper-based paints.

“If achieved, this improved coating could not only be exempt from future environmental constraints and regulations, it would also provide increased fuel efficiency and velocity of Navy vessels,” McElvany said.

Brennan realized that sharks remain largely free of plants and barnacles despite spending their entire lives submerged. That contrasts, for example, some other large-bodied marine species such as whales, which attract marine growth.

Sharks have placoid scales, which consist of a rectangular base embedded in the skin with tiny spines or bristles that poke up from the surface – the reason a shark’s skin feels rough to the touch. Brennan decided to try mimicking that surface with an artificial coating to see if it would also have antifouling properties.

His first product: a combination plastic/rubber coating that a microscope reveals is made of billions of tiny raised diamond-shaped patterns. Each “sharklet” diamond measures 15 microns, or 15 thousandths of a millimeter, and contains seven raised ribs that at close examination resemble different lengths of raised horizontal bars.

Laboratory tests show that the coating prevents a very common and detrimental type of algae, called Ulva, from becoming established because the algae’s spores have great difficulty attaching to the diamond-shaped configuration.

“It normally sticks to everything, but we have reduced spore settlement by 85 percent,” Brennan said. “The only place the spores land right now is where we have a defect in the pattern.”

That’s a major advance, as the algae is a major problem for nuclear submarines, carriers and battleships because it accumulates on inlet ports used to cool nuclear reactors. “It can severely inhibit the vessel’s ability to operate,” Brennan said.

McElvany called the finding “exciting,” saying Brennan and colleagues’ research “is both unique in their approach and exciting in terms of their efficacy” in deterring the Ulva spores.

“The big hurdles that remain are to develop textures, patterns or chemistry on the surface that will also inhibit the settlement of a wide variety of the main marine foulers, such as barnacles,” he said.

The UF team, which also includes UF research scientist Ron Baney and numerous graduate students, hopes to achieve that goal with its latest version of the coating. In research recently patented, Brennan and his colleagues have made the diamond-shaped pattern dynamic, or changeable, under the influence of a low-power electric current.

The ribs on the surfaces swell and shrink -- in effect flexing in and out from the hull surface – as the current varies. That may be useful because the movement could prevent the accumulation of silt and other debris on the hulls, which is often a precursor to plant and barnacle growth, he said.

Both the original and newer versions of the coatings are being tested in labs in Florida, England, Hawaii, California and Australia, with full-scale ocean testing set to begin in March, Brennan said. The diversity of locations is important because each has different species of fouling plants and barnacles, he said. The changeable version of the coating may also have an important biomedical application, Brennan said. Tests have revealed that it can impede the attachment and growth of cells, which may make it useful on medical implants such as catheters and heart valves. Currently, cell and tissue growth on these implants often reduces or impedes their function.

“Our whole concept is a surface design that we can tailor to the application,” whether in the ocean or human body, Brennan said.


Story Source:

The above story is based on materials provided by University Of Florida. Note: Materials may be edited for content and length.


Cite This Page:

University Of Florida. "Sharks Provide Key Insight For New, Non-toxic Anti-algae Coating." ScienceDaily. ScienceDaily, 15 March 2005. <www.sciencedaily.com/releases/2005/03/050310180225.htm>.
University Of Florida. (2005, March 15). Sharks Provide Key Insight For New, Non-toxic Anti-algae Coating. ScienceDaily. Retrieved April 24, 2014 from www.sciencedaily.com/releases/2005/03/050310180225.htm
University Of Florida. "Sharks Provide Key Insight For New, Non-toxic Anti-algae Coating." ScienceDaily. www.sciencedaily.com/releases/2005/03/050310180225.htm (accessed April 24, 2014).

Share This



More Plants & Animals News

Thursday, April 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Fungus Killing Bats, Spreading in US

Deadly Fungus Killing Bats, Spreading in US

AP (Apr. 24, 2014) A disease that has killed more than six million cave-dwelling bats in the United States is on the move and wildlife biologists are worried. White Nose Syndrome, discovered in New York in 2006, has now spread to 25 states. (April 24) Video provided by AP
Powered by NewsLook.com
Blood From World's Oldest Woman Suggests Life Limit

Blood From World's Oldest Woman Suggests Life Limit

Newsy (Apr. 24, 2014) Scientists say for the extremely elderly, their stem cells might reach a state of exhaustion. This could limit one's life span. Video provided by Newsy
Powered by NewsLook.com
Raw: Kangaroo Rescued from Swimming Pool

Raw: Kangaroo Rescued from Swimming Pool

AP (Apr. 24, 2014) A kangaroo was saved from drowning in a backyard suburban swimming pool in Australia's Victoria state on Thursday. Australian broadcaster Channel 7 showed footage of the kangaroo struggling to get out of the pool. (April 24) Video provided by AP
Powered by NewsLook.com
Could Marijuana Use Lead To Serious Heart Problems?

Could Marijuana Use Lead To Serious Heart Problems?

Newsy (Apr. 24, 2014) A new study says marijuana use could lead to serious heart-related complications. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins