Jellyfish Even More Efficient Propulsors than Previously Believed [VIDEO]

Researchers from the Marine Biological Laboratory have identified a new stage in jellyfish locomotion that, they say, contributes greatly to the animal's movement.

Jellyfish are one of the planet's most efficient propulsors, a trait that allows them to overrun entire ecosystems even when competing with much swifter animals.

"It seems counterintuitive," lead author Brad Gemmell, who worked at the MBL as a postdoctoral scientist, said in a statement. "Fish are visual hunters; they can detect prey from a distance and they have very good chemosensory capabilities. Jellyfish, by comparison, are seemingly poor predators. They need direct contact with their prey through their tentacles, to feed, and they aren't fast swimmers."

Evolution hasn't completely failed the brainless, heartless creatures, however.

"A jellyfish expends far less energy getting from point A to point B," Gemmel explained, meaning that a little goes a long way in terms of energy output and movement. This allows a significant portion of energy to then be channeled into growth and reproduction.

Key to this efficiency is a phase of motion that begins after the animal contracts -- a stage the researchers have named "passive energy recapture."

"The contraction phase is when the animal is moving the fastest," Gemmell said. "That is when you see these vortex rings [in the water] being ejected behind the animal."

Once believed to be a moment of pause for the jellyfish, the researchers found a second vortex ring that comes up the underside of the animal and gives its a second boost during this stage.

"That secondary vortex ring contributes up to 30 percent of the total distance the animal travels with each contraction, which is significant," Gemmell said. "It's a neat little trick they use. The animal is paused; it's not expending any additional energy, but it is still accelerating."

Going forward, the scientists hope to render the underwater video system they developed from 2D to 3D capabilities. Doing so, Gemmel said, "would be totally revolutionary."