October 19, 2013 | David F. Coppedge

The Ocean's Most Efficient Swimmer Is… A Jellyfish

They look so lazy, drifting among the waves, but jellyfish are powered by such efficient mechanisms, the Navy wants to imitate them.

Nature explained “Why a jellyfish is the ocean’s most efficient swimmer.”  The inputs to the calculation are not speed, but results for the power input.  The subheading explains, “Elastic body allows moon jellyfish to travel extra distance at no energy cost.” Ed Yong writes,

Amazing FactsThe sockeye salmon is a sleek torpedo that uses its strong muscles to leap up waterfalls. The moon jellyfish (Aurelia aurita) is a flimsy blob that drifts along like a gently pulsating bell. The salmon is obviously the more powerful swimmer, but a study has revealed that the jellyfish outclasses it in efficiency. For its mass, the jellyfish spends less energy to travel a given distance than any other swimming animal.

The article explains how relaxation of the bell allows the jellyfish to travel 80% more for nothing.  Yong concluded, “the moon jellyfish’s energy-saving trick might be useful when designing ocean-going machines — from floating buoys to autonomous underwater vehicles.”  Sure enough, the Navy is looking into it, reports Science Daily.

Virginia Tech College of Engineering researchers are part of a national study that has cracked how jellyfish move with the lowest cost of transport of any animal. The findings will be used as researchers continue to design bio-inspired jellyfish for the U.S. Navy.

The Navy already has a 170-pound prototype it is testing.  New Scientist also explained some of the physics behind the jellyfish’s swimming efficiency.  It was “remarkably difficult” to model the action because of the soft body of the jellyfish.  Science Daily included more amazing facts about these seemingly “primitive” creatures of the sea:

“Jellyfish are attractive candidates to mimic because of their ability to consume little energy owing to a lower metabolic rate than other marine species, survivability in varying water conditions, and possession of adequate shape for carrying a payload,” Priya said in 2012 when several of the smaller robotic jellyfish were unveiled. “They inhabit every major oceanic area of the world and are capable of withstanding a wide range of temperatures and in fresh and salt waters. Most species are found in shallow coastal waters, but some have been found in depths 7,000 meters below sea level.

Who would have thought that the humble jellyfish would be the subject of a Nature article on power production in biomechanics.

Like other animals that appeared abruptly during the Cambrian explosion, jellyfish show up with “instant body plans” and no transitional forms, as explained by Evolution News & Views.  We’ve reported before how some jellyfish have complex eyes, too (4/28/11).  Evolution is the bad habit of taking things for granted.  Creationism believes things were created wisely for a purpose.  That assumption is a stimulation to do good science, and to imitate the exquisite engineering that we in fact find in nature.


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  • rockyway says:

    ‘Evolution is the bad habit of taking things for granted.’

    – I like that way of putting things, and agree entirely. Textbook evolutionary theory claims that all the wonders of this planet happened by accident – and in doing so it takes intelligence, mind, personhood, purpose, information and design for granted… as if they weren’t needed.

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