Whereas pandas on land are called "lazy" for moving slowly, jellyfish and eels have long been considered graceful swimmers using an impressively low amount of energy to get around--without being slow. A recent study has learned something about the trick that eels and jellyfish are employing to do this.
Scientists from Stanford University, University of South Florida, Roger Williams University and Providence College, performing research at the Marine Biological Laboratory (MBL) in Woods Hole, Mass., recently published that study in the journal Nature Communications, and they say that its learnings may be applied to vehicle design later.
The team learned that jellyfish and eel-like lampreys bring water to themselves. That is, they advance forward not by acting against the water but by sucking it toward themselves.
"Until now, it has been widely assumed in the literature and the text books that animals swim primarily by pushing against the fluid to generate high pressure and move the animal forward," said Brad Gemmell of University of South Florida in a release. "However, it turns out that at least with some of the most energetically efficient swimmers, low pressure dominates and allows these animals to pull themselves forward with suction. 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."
In the study, the researchers watched lampreys swim through water in a tank that contained tiny glass beads. These last were lighted with a laser. By watching the beads as the animals swam through them, the scientists were able to visualize the movement's flow and timing. They also measured the efficiency of the creatures' swimming, using high-speed digital cameras that captured movement by the fraction of a second, confimed a release.
Lampreys swimming in undulating movements are making a low-pressure water pocket inside the bends of their body. Then the water in front of the lampreys moves to fill that pocket. In-flowing water draws the animals forward.
"The new method to calculate pressure fields around freely swimming organisms allowed us to look at both high and low pressure contributions to locomotion," said Gemmell in the release. "This is when we found that low pressure or suction was actually the dominant means of moving the animals forward."
The researchers saw the same principles taking place in jellyfish swimming, the release confirmed.
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