Until now, scientists weren’t entirely sure how marine life like jellyfish and eels are able to move so effortlessly from point A to point B, using less energy than it takes any other moving life form ever measured. But researchers at the University of South Florida (USF) believe they may have now found the answer. Rather than propel themselves forward by pushing against the water, jellyfish and eels actually suck the water toward them.

A team of scientists led by Dr. Brad Gemmell, an assistant professor in the Department of Integrative Biology, set up a tank of water containing tiny glass beads illuminated with a laser. High-speed digital cameras recorded the movement of lampreys in the tank, and allowed Gemmel and his team to visualize how the eel-like fishes' swimming motion affected the movement of the beads. They found that the lampreys' undulating motions created a pocket of low-pressure water inside each bend of their bodies. Water ahead of the lampreys filled the low-pressure pocket and pulled them forward.

Jellyfish were used in the same experiment with similar conclusions, despite their different shape and swimming motion.

The video below shows what the researchers observed with the jellyfish in the tank.Researchers found that combinations of high pressure and low pressure acting either opposite or in the direction of forward motion contributed to how both sets of animals propelled themselves through the water using as little energy as necessary.

"Given our findings, we may have to rethink our ideas about some of the evolutionary adaptations acquired by swimming animals and how we approach vehicle design in the future," says Gemmell.

Over the last several years, other universities have experimented with robots modelled after jellyfish, along with tiny jellyfish-inspired pumps that could be implanted in humans. According to the USF, the recent findings of Gemmel's team could impact everything from evolutionary to functional ecology and even highly energy-efficient bio-inspired designs.

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