Jellyfish & Lampreys Swim with Unmatched Efficiency Using Low-Pressure Suction-Based Propulsion; Mechanism Had Previously Been Completely Misunderstood; Discovery May Revolutionize Ship Design

Millions of years ago, even before the continents had settled into place, jellyfish were already swimming the oceans with the same pulsing motions we observe today. Now, through clever experiments and insightful math, an interdisciplinary research team has revealed a startling truth about how jellyfish and lampreys, another ancient species that undulate like eels, move through the water with unmatched efficiency. "It confounds all our assumptions," said John Dabiri, Ph.D., a Professor of Civil and Environmental Engineering and of Mechanical Engineering at Stanford. "But our experiments show that jellyfish and lampreys actually suck water toward themselves to move forward, instead of pushing against the water behind them, as had been previously supposed." This new understanding of motion in fluids is published online on November 3, 2015 in an open-access article in Nature Communications article that Dr. Dabiri co-authored with Dr. Brad Gemmell of the University of South Florida, Dr. Sean Colin of Roger Williams University in Rhode Island, and Dr. John Costello of Providence College, also in Rhode Island. The Nature Communications article is titled “Suction-Based Propulsion As a Basis for Efficient Animal Swimming.” Dr. Dabiri, an engineer, and his collaborators, all biologists affiliated with the Marine Biological Laboratory at Woods Hole, Massachusetts, have spent years studying the propulsion systems of jellyfish and eel-like lampreys. Both animals long ago evolved into efficient swimmers. Each minimal pulsing or undulating movement helps them cover a significant distance. Studying nature for clues to improve human-made technologies is part of a field called biomimetics, and the collaborators originally set out to seek insights that might improve the design of submarines, ships, and the like. About three years ago, Dr.
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