A while back we discussed the rowing system that resembles an umbrella.

That made reading this article even more fascinating:
http://www.physorg.com/news165234976.html

The harmonic effect to conserve energy really made me think.

Another news link here:
http://gizmodo.com/383281/aquajelly-and-airjelly-robot-jellyfish-at-home-in-the-\
water-or-the-sky
Apparently there is a model that can fly.

A PDF file here:
http://www.iop.org/EJ/abstract/0964-1726/18/8/085002/

An earlier robot by the same company:
http://www.newscientist.com/article/mg19526225.800-robotic-ray-swims-rings-aroun\
d-propeller-craft.html

"As it glides sedately beneath the waves, the ray's languid grace belies a
stunning capacity for underwater manoeuvres. With a flap of its wings, Aqua ray
can swim upside down, loop the loop, hover or turn on a dime.

As agile as a real manta ray, the rubbery, robotic acrobat (pictured right) is
the handiwork of Rudolf Bannasch and Leif Kniese of bio-inspiration firm
EvoLogics in Berlin, Germany, and could kick-start a new generation of
autonomous underwater vehicles.

Over the last decade AUVs, which are mostly propeller-driven, have been probing
the oceans' vast depths without the need for human pilots. But although they can
be customised for either fine manoeuvring or long-distance cruising, only rarely
can they do both."

Bill