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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Video: The Secret of the Jellyfish
19 February 2014 3:45 pm
Nothing we have ever built can ply water as efficiently as the humble jellyfish. This video shows the pressure systems created with each of its thrusts, with vortices of low pressure (blue) rolling from the front of its bell-shaped body that meet up with the bulge of high pressure (red) that forms behind it. This pressure gradient pulls the jellyfish through the water with little exertion. Research on jellyfish propulsion over the past 2 years revealed a key design feature that makes this translucent beast so efficient: bendiness. (This was confirmed by building robotic jellyfish—the bendy models left the stiff ones behind.) But are jellyfish the only animals to have discovered the magic of bendiness? A new study examined the propulsive limbs of 59 animal species, from the flukes of killer whales and the wings of moths and bats to the winglike feet of sea slugs. Not only is bendiness ubiquitous, but it is finely tuned. No matter if a creature lives in air or water, whether it propels itself with skin, feather, or gelatinous flaps, the propulsive limbs of all animals seem to have the same bendy design constraint: About one-third of the length of the structure flexes during steady motion, and the bending angle ranges from 15° to 40°. This narrow “morphospace,” described online this week in Nature Communications, can’t be the result of shared genes. The same solution was reinvented countless times. Instead, the finely tuned bendiness of fins and wings is just good design, discovered again and again by evolution. Being stiff is literally a drag.