An underwater view of the ocean filled with tubular creatures known as pyrosomes.
Hilarie Sorensen/University of Oregon
Millions of tubular sea creatures called pyrosomes have taken over the Pacific Ocean in an unprecedented bloom that has scientists baffled.
These bumpy, translucent organisms look like sea cucumbers that range in size from six inches to more than two feet long. But they’re actually made up of hundreds of tiny animals knit together with tissue into a filter-feeding cylinder.
Pyrosomes collected off the Oregon coast range in size from a few inches to more than two feet long.
Hilarie Sorensen/University of Oregon
And they're everywhere, filling the waters off the West Coast all the way up to Alaska, and washing up on beaches.
One research boat caught 60,000 of them in five minutes. They're so thick in Alaska that fishermen gave up on fishing because their hooks were coming up full of pyrosomes instead of salmon.
Jennifer Fisher, a research assistant with Oregon State University’s Hatfield Marine Science Center in Newport, makes regular research trips to monitor ocean conditions. She started seeing pyrosomes in her research net in February, and a GoPro camera on the net revealed an eerie underwater habitat filled with the pickle-shaped creatures.
“Basically as far as the eye can see: pyrosomes,” she said. “We were dumbfounded.”
Pyrosomes are common in the tropics, where they can reach a length of 30 feet and often glow in the dark. That likely explains their name, which in Greek translates to “fire body.” According to Fisher, they do show up in the ocean off the Northwest from time to time – but never in these numbers.
“Why they’re here now is unknown at this point,” Fisher said. “We’ve had warm ocean conditions over the past couple years, and something has brought them here. They’re just flourishing. It’s just very unusual to find them so close to shore, so evenly distributed, and so abundant.”
It’s strange, researchers say, because the warm ocean water that has been hanging out off the West Coast since 2014 has dissipated this year. And the Pacific has had plenty of warm water events in the past without seeing massive blooms of pyrosomes.
No one knows what the effects of the bloom will be, but scientists worry that if all the creatures die off at once they could sink to the seafloor and suck up all the oxygen as they’re decomposing, creating a dead zone for marine life.
Each pyrosome is made up of individual zooids – small, multicellular organisms – linked together in a tunic to form a tube-like colony.
Courtesy of National Oceanic and Atmospheric Administration
Richard Brodeur, a research biologist with the National Oceanic and Atmospheric Administration, is leading an effort to collect live pyrosomes to study in his lab in Newport, Oregon.
“We’re trying to learn as much as we can about these guys,” he said. “I’ve been working for a long time, and I’ve never seen one until now. So, we’re kind of catching up. … It’s really a mystery to us why this is happening.”
He wants to look at how they feed, how they orient themselves vertically in the water, and their swimming speed.
“They’re usually in the tropics farther off-shore,” he said. “People haven’t done anything experimentally with these guys.”
Brodeur said the pyrosomes might be a lingering effect of the warm water “blob” that in 2015-16 brought in unusual marine life including a tropical sea snake and red crabs. Though water temperatures have dropped from previous years, he said, “they’re still way above normal, and we’re still getting unusual things going on.”
Fisher will continue to monitor for the pyrosomes, and she’s interested to see how long they stick around.
“They often bloom in large numbers and then conditions become unfavorable for them and they go away,” she said. “I think that’s when we might learn more about why they’re here is when they leave looking at what conditions caused them to go.”