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Jet-propelled sea creatures could improve ocean robotics

Scientists at the University of Oregon have discovered that colonies of gelatinous sea animals swim through the ocean in giant corkscrew shapes using coordinated jet propulsion, an unusual kind of locomotion that could inspire new designs for efficient underwater vehicles.

The research involves salps, small creatures that look similar to jellyfish that take a nightly journey from the depths of the ocean to the surface. Observing that migration with special cameras helped UO researchers and their colleagues capture the macroplankton’s graceful, coordinated swimming behavior.

“The largest migration on the planet happens every single night: the vertical migration of planktonic organisms from the deep sea to the surface,” said Kelly Sutherland, an associate professor in biology at the UO’s Oregon Institute of Marine Biology, who led the research. “They’re running a marathon every day using novel fluid mechanics. These organisms can be platforms for inspiration on how to build robots that efficiently traverse the deep sea.”

The researchers’ findings were published May 15 in the journal Science Advances. The study included collaborations from Louisiana Universities Marine Consortium, University of South Florida, Roger Williams University, Marine Biological Laboratory and Providence College.

Despite looking similar to jellyfish, salps are barrel-shaped, watery macroplankton that are more closely related to vertebrates like fish and humans, said Alejandro Damian-Serrano, an adjunct professor in biology at the UO. They live far from shore and can live either as solitary individuals or operate in colonies, he said. Colonies consist of hundreds of individuals linked in chains that can be up to several meters long.

“Salps are really weird animals,” Damian-Serrano said. “While their common ancestor with us probably looked like a little boneless fish, their lineage lost a lot of those features and magnified others. The solitary individuals behave like this mothership that asexually breeds a chain of individual clones, cojoined together to produce a colony.”

But the most unique thing about these ocean creatures was found during the researchers’ ocean expeditions: their swimming techniques.