After storms, beaches can suddenly fill with tiny blue discs fringed with tentacles — creatures many people assume are jellyfish. But new research suggests those eye-catching drifters, known as blue buttons, may be far older and tougher than scientists once believed, Earth.com reported.
According to a study published in Scientific Reports, researchers in Japan found that the blue button may survive for years while floating on the ocean's surface. That marks a major shift from earlier assumptions that the animal lived for less than a year.
To study them more closely, the team collected 10 colonies from the Kanagawa coast and maintained them in aquariums for 21 days with filtered seawater, gentle aeration, sunlight, and daily feedings of newly hatched brine shrimp.
By tracking their growth, the researchers found that smaller colonies expanded quickly — in some cases by about 0.002 inches per day — while larger ones barely grew. Using those measurements, they estimated that colonies around 0.16 inches across were about three months old, 0.47-inch colonies were near one year old, and the biggest ones, at roughly 0.91 inches, may survive for about five years.
Blue buttons are part of the neuston, a little-understood community of organisms that live at the thin boundary between the ocean and the atmosphere. These creatures help support marine food webs by feeding predators and moving nutrients across vast distances.
The findings also change how people should think about the bright blue blobs that wash ashore. Blue buttons are not single jellyfish-like animals but colonies of specialized zooids, with different parts responsible for feeding, defense, and reproduction. That makes them more like living floating systems than simple bits of ocean debris.
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The Japanese team's biggest breakthrough was simply keeping blue buttons alive long enough to study them in detail. That gave researchers a clearer picture of how the organisms grow and how their chitin-based floats develop in layers from the outer edge, almost like tree rings.
Those floats may help explain their longevity. Unlike some other surface drifters, blue buttons sit on sturdy, air-chambered discs that provide buoyancy and durability in a harsh environment filled with ultraviolet radiation, waves, and temperature swings.
"From our observations of these colonies, we can now estimate that blue buttons may actually live for several years, drifting on the ocean surface. This is much longer than previously thought, which was less than a year," Kohei Oguchi, co-author of the study, said, per Earth.com.
For beachgoers, the takeaway is simple: look, don't touch. Blue buttons have stinging cells, and it is best to leave washed-up marine animals alone and report unusual strandings if local authorities request it.
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