Washington: As if the sight of an angry shark with a mouthful of razor sharp fangs wasn't enough to inspire fear, US researchers have found teeth-like scales on their skin that may help them make quick underwater turns.
These flexible scales "make them better hunters by allowing them to change directions while moving at full speed," said the findings by researchers at the University of South Florida and the University of Alabama.
The scales control how water flows across the shark's body, said Alabama researcher Amy Lang, who presented her team's findings at the American Physical Society's Division of Fluid Dynamics annual meeting in Long Beach, California.
"In nature, if you look at surfaces of animals, you'll see that they are not smooth," she said.
"They have patterns. Why? One common application of patterning a surface is to control flow -- think of the dimples of a golf ball that help the ball fly farther," she added.
"We believe scales on fast-swimming sharks serve a similar purpose of flow separation control."
The study examined shortfin mako sharks and found that they were covered with these small teeth-like scales, which were more narrow where they attached to the skin than they were at the tops of the scales.
"This tapered shape enables the scales to be easily manipulated to angles of 60 degrees or more, endowing them with movement called 'denticle bristling,'" said the study.
Interestingly, the scales were only found in places where "flow separation," or the way fluid moves around a moving object by approaching it at first and separating from it near the rear, was likely to occur, such as near the gills.
Using those teeth-like scales, sharks can probably control their movements in the water better than other species.
Their skills might be useful for human technology, particularly in the form of aerodynamics and travel.
"As we investigate further, we imagine applications of controlling flow separation in design of aircraft, helicopters, wind turbines -- anywhere flow separation is an issue," Lang said.
First Published: Wednesday, November 24, 2010, 18:09