The sea monster goes ‘bloop’—or does it?
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In 1997, the U.S. National Oceanic and Atmospheric Administration (NOAA) detected an unusual noise in the remote south Pacific. This in itself was not remarkable. NOAA’s undersea microphones or “hydrophones,” primarily used for monitoring geological activity, often pick up sounds whose origin is not immediately apparent. NOAA researchers give these sounds nicknames, including Upsweep, Sea Train, and Julia (named because it sounded like a woman’s muffled voice). But this particular noise was like nothing scientists had heard before.
Extremely low in frequency, it was also extremely loud, picked up by sensors over 3,000 miles apart. The mystery sound rose and fell over the course of one minute. When sped up 16 times to make it audible to human ears, it sounded like “bloop.” This became the noise’s nickname as scientists puzzled over what could have produced it.
What was special about the Bloop?
Due to its rapid changes in frequency, the Bloop bore some resemblance to marine animal sounds. However, it was much, much louder than a blue whale, the loudest-known animal. The call of a blue whale can be heard about 1,000 miles from its source. While impressive, this is less than a third of the distance that the Bloop traveled.
“We’re suspecting that it’s ice off the coast of Antarctica, in which case it’s darn loud,” NOAA oceanographer Chris Fox said of the Bloop in 2001. Though the Bloop was louder than the sounds typically associated with shifting ice, it was so much louder than any known animal that NOAA considered crumbling polar ice floes to be the most plausible explanation.
However, in a separate interview Fox gave for New Scientist in 2002, he acknowledged that the Bloop had similarities to animal sounds. This led New Scientist writer David Wolman to speculate, “Is it even remotely possible that some creature bigger than any whale is lurking in the ocean depths? Or, perhaps more likely, something that is much more efficient at making sound?”
Was the Bloop a sea monster?
Other media outlets soon took this remote possibility and ran with it. “One theory is that [the Bloop] is a deep sea monster, possibly a many-tentacled giant squid,” CNN reported in 2002. (While the giant squid is very real, it is not known to be capable of making noise). The mystery of the Bloop became a tantalizing symbol of how little we know about the ocean, and a fixture in the lore of cryptozoology: The study of animals not confirmed to exist, such as Bigfoot and the Loch Ness Monster.
In 2003, cryptozoologist Loren Coleman reported that the Bloop “most likely comes from a marine beast,” comparing it with mystery sounds recorded in Loch Ness. However, Coleman noted that the sounds from Loch Ness were later confirmed to have come from geological activity, not Nessie.
Cryptozoology is not considered a science because it doesn’t usually follow the scientific method or depend on scientific standards of evidence. This leaves room for creative speculation that can stretch into fantasy.
A Google image search for “the Bloop” turns up artwork of imaginary leviathans based on whales, anglerfish, or squid. One such creature became a fanmade addition to the video game Subnautica, in which players explore an alien ocean.
Sea ice can get vocal, thanks to climate change
Large glaciers, like the ones found at the South Pole, can make noise when they scrape against the ocean floor or each other, or when chunks of ice split off from them, a process called calving. An extremely large instance of calving can even shake the ground, causing a glacial earthquake, also known as a cryoseism or icequake.
To confirm the Bloop’s origin, scientists compared it closely with recorded sounds that, despite being less loud, were known to have come from polar ice. The results confirmed NOAA’s initial speculations.
“The broad spectrum sounds recorded in the summer of 1997 are consistent with icequakes generated by large icebergs as they crack and fracture,” NOAA reports. This includes not only the Bloop, but the other named sounds NOAA recorded at the South Pole (even the eerily humanlike “Julia”).
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Arctic ice at the North Pole has caused similar phenomena, such as the Ping, a persistent underwater ringing recorded in the summer of 2017. At the time, local hunters blamed the Ping for scaring away game.
The Bloop may not have been the sound of a sea monster, but it did carry an important message for humanity: an early warning about climate change. As rising global temperatures threaten the polar ice floes, loud and previously-unknown sounds from the breakdown of ice are becoming more frequent, impacting polar ecosystems.
A 2021 study on marine noise in the Southern Ocean describes it as “a form of ocean pollution that may affect fauna ranging from tiny zooplankton to enormous whales.” Many marine animals use sound-based sonar for navigation, communication, and even hunting. Marine noise can interfere with these animals’ migration and feeding patterns, impacting their ability to survive.
Research into the ecological effects of marine noise has been limited, especially in Antarctica. The 2021 study calls on signatory parties of the Antarctic Treaty to come together to address options for managing and mitigating these disruptive (and very loud) sounds in the polar ocean.
The sea is still full of mystery sounds
Feeling a bit disappointed that a giant sea monster didn’t make the Bloop? Sometimes, strange polar ocean sounds really do turn out to come from animals. Australian surveyors first recorded a persistent underwater quacking dubbed the Bio-Duck noise in the 1960s. Its origin was unknown until 2014, when researchers proved that the culprit was not some seagoing duck but minke whales.
2014 also marked the first recording of the Western Pacific “Biotwang” near the Mariana Trench. Described as “Star Wars-like” and “a frog burping in space,” the Biotwang was later traced to the Bryde’s whale. “Anybody who’s not familiar with whales would never think [the Biotwang] was made by an animal,” said NOAA researcher Ann Allen.
Then there are open cases, like the call of the “52-hertz whale” drifting through the North Pacific since the 1980s. Named for its frequency, which is much higher than a typical whale’s song, this sound was once thought to come from a single animal. Current recording patterns suggest there are at least two. But since neither high-voiced whale has ever been seen, scientists can’t say if they represent unusual members of a known species, or an unknown one.
Noisy as it is, the ocean still hasn’t told us all its secrets.
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