A Glowing Invasion of 'Fire Bodies' Is Underway in the Pacific

A young pyrosome colony glowing blue. The individual zooids within the colony are all clones of each other. . (Photo: Nick Hobgood/WikiMedia)

Bizarre, gelatinous, and glowing jellyfish-like organisms known as a pyrosomes are showing up in massive numbers never before recorded off the U.S. West Coast. And marine scientists are completely stumped as to why.

"It's really weird," Jennifer Fisher, a faculty research assistant with Oregon State University's Hatfield Marine Science Center, told National Geographic. "I've never seen anything like it."

Pyrosomes are actually colonies of hundreds or even thousands of tiny harmless creatures called zooids. They're all clones, with each individual capable of copying itself, and work together in unison to move through and filter the water for plankton. While some pyrosome colonies reach no larger than 2 feet, others, such as the magnificent one below, have been discovered in excess of 60 feet; with a filter mouth capable of swallowing a full grown human.

And yes, they glow. Their name originates from the Greek words “pyro” and “soma” or "fire body." Light-emitting bacteria in the tissues of the zooids creates a brilliant blue-green color that intermittently flashes and can be seen from great distances. Scientists believe the bioluminescence may be a communication method, a way to attract food plankton, or even scare predators away.

"I have just watched the moon set in all her glory, and looked at those lesser moons, the beautiful Pyrosoma, shining like white-hot cylinders in the water," the scientist T.H. Huxley observed in 1849.

You can see some of that brilliant glow in the video below.

Because pyrosomes have traditionally been so rare and mysterious, marine scientists jokingly refer to them as "the unicorns of the sea." That all changed this spring when millions up millions began showing up in nets and on beaches from Oregon to Alaska. Traditionally sighted in much warmer waters, a pyrosome migration of this size is unprecedented.

"They got here and have been flourishing—just super abundant," Fisher added. "But that's the weird thing: Why here? Why now?"

While scientists struggle to figure out the cause of the migration, fisheries are grappling with how best to avoid them. As it turns out, the gelatinous zooids within a pyrosome colony are the perfect size for gumming up equipment.

“There’s just so many of them, it’s hard to pick them out,” shrimper Steve Davis told the Chinook Observer. "They range from the size of a pinkie finger to almost a foot long, and they seem to float in packs. If a boat is unlucky enough to hit a patch of them, you go somewhere else and hope that they’re not that thick."

You can see just how many there are in some waters courtesy of this footage captured off the coast of Newport, Ore. by biology student Hilarie Sorensen.

With so little known about pyrosomes, the next step for marine scientists is to take advantage of this anomalous abundance of the species to gauge their impact, if any, on the overall ecosystem.

“We have a lot of questions and not many answers,” Ric Brodeur of the Northwest Fisheries Science Center’s research station in Newport, Oregon, told NOAA. “We’re trying to collect as much information as we can to try to understand what is happening, and why.”