Professor George Lauder said that body stabilizing effects or the tight structure that may change a swimmer's circulation could be responsible for gained swimming speed. "I’m convinced [the swimsuits] work, but it’s not because of the surface," Lauder said. Even if those suits mimic a shark's sandpaper-like skin with countless tiny denticles that are believed to help the shark - and a swimmer - to move faster through the water, the scientist said that they also create low-pressure zones or "leading-edge vortices" that is likely to propel the shark forward. "So my hypothesis is that these structures that make up shark skin reduce drag, but I also believe them to be thrust-enhancing,” Lauder noted.
Interestingly, this effect is meaningless on a rigid surface and can only be witnessed on a flexible base.
“In life, sharks are very flexible. Even hammerheads and large ocean sharks are quite flexible,” Lauder said. “If you watch a shark swim, the head does not move very much, so it could be that the denticles on the head are mostly reducing drag, but those on the tail are enhancing thrust. But we don’t know what that balance may be. Ultimately, though, one of the key messages of this paper is that shark skin needs to be studied when they’re moving, which hadn’t been done before.”
In their tests, the scientists used samples of shark skin and recorded the particle streaming by the denticles using high-speed cameras. No significant results have been published so far, but Lauder noted that they also want to look at swimsuit materials, and at creating artificial sharkskin with higher and lower densities as well as varying sizes of denticles.