Jellyfish 'invisible' to Prey

GOTHENBURG, Sweden, Oct. 12 (UPI) — A voracious jellyfish has evolved the ability to sneak up on its prey like a high-tech stealth submarine and appear “invisible,” European researchers say.

The North American comb jellyfish has a large gelatinous body, increasing its chances of encountering prey, but those prey organisms are often highly sensitive to movements in the water.


Nevertheless, comb jellyfish catch large amounts of copepod plankton, which are known for their sensitive escape response, ScienceDaily.com reported.

“Copepods have a well developed ability to detect even the slightest water disturbance,” says Lars Johan Hansson, a researcher at the Department of Marine Ecology at the University of Gothenburg in Sweden. “They can swim well clear of the source of water deformation in just a split second. How the comb jellyfish is able to approach and catch some of the animal world’s most vigilant plankton has up until now been unknown.”

Researchers at the Department of Marine Ecology at the University of Gothenburg used advanced video technology to study water flows around and within the comb jellyfish.

“It emerged that the comb jellyfish uses microscopic, hairlike cilia inside its oral lobes to generate a feeding current that carefully transports water between the lobes,” Hansson said. “As the water accelerates slowly and is transported undisturbed into the jellyfish together with the prey, there is nothing that alarms the prey until it is next to the capture site inside the lobes, by which time it’s too late to escape. This makes the jellyfish a hydrodynamically silent predator.”

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