Over time, scientists have learned that many non-human organisms like to congregate in one place, especially when all the green leaves make the transition between life and death; signaling the end of one season and the beginning of another. Most of this boils down to evolution. when the time comes, creatures take to the land and sky, sometimes making the treacherous journey across the world in search of a more inviting habitat. 

Velella velella (Image Credit: Yakafaucon Image Perso)

However, survival isn’t the only reason creatures gather in large numbers Recently, one strange organism invaded various beaches on the west coast, bombarding surfers and bystanders with billions of Velella velella “jellyfish (the quotation marks are there because they aren’t technically jellyfishes, just jellyfish-like creatures). One singular creature — with its bluish color and circular shape — is so beautiful, it’ll almost take your breath away.

However, its defining feature has nothing to do with its color, shape or its impressively small size, but its translucent fin that doubles as a sail, allowing the creature to get carried off by the wind when it ventures too close to the water’s surface… and it DOES like the surface. Most spend 99% of their lives floating on top of the water, with the 1% below the surface spent during the larval stage (this is not a good practice either, as the vast majority wind up dying on shore). Interestingly, they kind of bobble above the water, encased in protective bubbles of gas

The interestingness doesn’t end there either. “It’s a very curious animal. It’s considered a colony, kind of like a coral head,” said Kevin Raskoff, a professor of Biology at Monterey Peninsula College. “If you were to remove one, it wouldn’t survive. It really kind of twists the mind around about what is the individual exactly, as opposed to what is a member of a colony. So it’s a bit of biology that has actually perplexed biologists for hundreds of years.”  

The Invasion:

The invasion started nearly two weeks ago, when they appeared in large numbers in Humbolt county on July 13. Since then. The phenomenon has become more wide-spread, with similar sights reported in the states of Oregon and California.“The numbers, if you extrapolate, are awe inspiring,”  remarked Raskoff, “With some of my students we counted more than a thousand per meter,” he continued. “The numbers get astronomical pretty fast.”

Biologists are unsure of what this sudden onslaught of blue, “by-the-wind sailor” jellyfish is about, but whatever the cause of the unusually high number of fatalities, it’s pretty unusual. By nature, these creatures generally prefer to keep to themselves, but when they do decide to congregate, they do it off-shore.“The last time we saw something like this was eight or nine years ago. They do seem to be more driven by prevailing wind currents.”

The combination of wind speed and ocean currents must be incredibly strong to drive so many of them onto the shore at any given time though, which becomes a bit more odd when you consider that the “invasion” isn’t a localized event, but something that is occurring in unexpected places (as the image above shows, it’s certainly not an isolated, once-in-a-blue-moon event).

A volunteer  (Emily Horton) with NOAA recently captured this photo off the coast of La Push, Washington.

If You Encounter One…

If you do happen upon one of them (or a few hundred million), take care not to disturb them. “Don’t touch them unless you know for sure this is what you’re dealing with,”says Jenn Moffat, an aquarist with Birch Aquarium in  San Diego, California. “They look very similar to Portuguese man-o’-war, and those have a pretty powerful punch as far as sting goes. So it’s just really better to stay away from them and just look at them and let them be.”

However, if you choose not to heed that piece of advice and disturb them anyway, they aren’t harmful. In fact, while their tentacles are equipped with stingers used to hunt and trap prey, their stingers aren’t powerful enough to  penetrate human skin, so if you get “stung” by one, the pain would likely be equivalent to a bee sting; nothing worse (but hey, who likes to get stung by a bee? No one, clearly, but bees don’t have a cute demeanor. Nothing about them screams “pick me up and take a selfie with me.  The internet will thank you.”)

Given the mysterious nature of the creatures themselves (and the questions we have about their interactions with fellow members of their colony), scientists can learn a lot by studying their behavior when they do venture near the shore, which becomes more difficult because, once on shore, they have a short shelf life.

Anyone that sees one can contact Jellyfish watch with information about their sighting. This marine biology research organization not only charts jellyfish and genetically related sea creatures, but the conditions on the beaches the sightings took place on (You can also “like” them on facebook here).


For related reading, learn about the lake that is completely overrun by jellyfish here. Learn about a jellyfish that can regrow its BRAIN in four days here.


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