A bio-mechanical experiment carried out at the University Of Pennsylvania School Of Engineering and Applied Science has answered a long-standing theoretical question if microorganisms swim faster or slower in elastic fluids and the answer is “slower”, the university website said

Assistant professor of mechanical engineering and applied mechanics department Paul Arratia, along with his student Xiaoning Shen, has conducted the experiment, results of which were published in Physical Review Letters.

The report said some animals, microorganisms and cells move in a wave pattern and they often do so through elastic fluids. Movements of worms on aerated wet soil and sperm racing toward an egg are all due to this phenomena which deal with our everyday life. Research for decades has been carried on in this area but not many have involved living organisms.

“There have been qualitative observations of sperm cells, for example, where you put sperm in water and watch their tails, then put them in an elastic fluid and see how they swim differently,” Arratia said in the University website.

“But this difference has never been characterized, never put into numbers to quantify exactly how much elasticity affects the way they swim, is it faster or slower and why,” he added.

The main barrier, however, for successfully testing these theories with living organisms is by developing an elastic fluid in which they can survive, perform normally and in which they can be efficiently observed under a microscope.

“In order to make our fluids elastic, we put polymers in them,” Arratia said. “DNA, for example, is a polymer. What we use is very similar to DNA, in that if you leave it alone it is coiled. But if you apply a force to it, the DNA or our polymer, will start to unravel.”

Arratia and Shen’s study was supported by the National Science Foundation