Jellyfish Build Walls of Water to Swim Around the Ocean | The New York Times

Note: Brad Gemmell, Jack Costello, and Sean Colin collaborate in the MBL Whitman Center to study locomotion in marine animals. Most of this jellyfish video was taken at MBL.

Locomotion through the seas can be arduous. Water is more viscous than air, and so underwater creatures must overcome strong frictional resistance as they swim.

To make things more difficult, liquid water provides nothing solid to push off against.

But lowly jellyfish, which have swum in the world’s oceans for half a billion years, have come up with an elegant, efficient means of propulsion.

A jellyfish swimming through laser sheet with tracer particles. Gemmell et al., 2020

Scientists have found that through their pulsing gelatinous undulations, at least one species of jellyfish creates vortices that rotate in opposite directions. Where flows of the two vortices meet, the collision creates a region when the water is stationary — in effect, creating a wall that the jellyfish use to push off.

With a simple body structure that is conveniently transparent, jellyfish “represent a really nice model to understand how animals interact with the water around them, to move very efficiently,” said Bradford J. Gemmell, a professor of integrative biology at the University of South Florida. “More efficiently than humans can create vehicles, for example.”

In a paper published Wednesday in Proceedings of the Royal Society B, Dr. Gemmell and his colleagues described the new discovery about jellyfish motion. Read more ...

Source: Jellyfish Build Walls of Water to Swim Around the Ocean – The New York Times