Planktonic microbes fire projectiles at their enemies, research shows

"This is a very exciting example of convergent evolution over a vast distance across the tree of life," zoologist Brian Leander explained.
By Brooks Hays   |   April 3, 2017 at 3:35 PM
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April 3 (UPI) -- Planktonic microbes are armed and dangerous. New analysis revealed the method used by plankton to fire projectiles at their prey and enemies.

"We think of plankton as the tiny alphabet soup of the ocean, floating around passively while larger organisms eat it," biologist Gregory Gavelis said in a news release. "But some planktonic microbes, like dinoflagellates, are predators and have developed incredible defensive and prey capture mechanisms."

The projectiles are called extrusomes. Until now, scientists didn't know exactly why the microbes fired the projectiles.

Researchers used 3D imaging technology to study the hunting techniques of two plankton species, Polykrikos kofoidii and Nematodinium sp.

Polykrikos uses a harpoon-like structure to puncture its prey and reel them in. Nematodinium fires a ring of capsules in a manner similar to a Gatlin gun.

"Nematodinium has the most sophisticated extrusomes we've seen so far," said UBC zoologist Brian Leander.

The scientists detailed their finding in the journal Science Advances.

Researchers also sequenced the microbe's genomes and were able to locate the genetic origins of their weaponry. Their analysis showed similar genes are responsible for the stinging organelles deployed by jellyfish.

"This is a very exciting example of convergent evolution over a vast distance across the tree of life," Leander explained. "The stinging nematocysts of cnidarians closely resemble those of dinoflagellates, but the ballistic mechanisms are different and they don't appear to share any genes."

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