Deep beneath the blue, blue waves of the Pacific Ocean, a true benthic monster makes its home.
Not the giant squid with its grasping, clasping arms; nor the sperm whale with its cunning eye and raking teeth.
Instead, this beast has the intricate folds of a forgotten pile of laundry, almost luminous against the inky darkness – the intestine-like configuration of the largest sponge humanity has ever seen.
NOAA scientists exploring the Papahānaumokuākea Marine National Monument in 2015 found it at a depth of 2,130 meters (6,990 feet), and measured its size.
The extraordinary colony came in at 3.7 meters long, 2.1 meters wide, 1.5 meters high – “about the size of a minivan”, according to NOAA.
And it could have been growing down there for a very long time.
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The discovery was made during NOAA’s 2015 Hohonu Moana: Exploring Deepwaters off Hawaiʻi expedition aboard the research vessel Okeanos Explorer.
Using a remotely operated vehicle called Deep Discoverer, the researchers spotted the enormous animal on a ridge deep beneath the ocean’s surface.
Two parallel laser beams projected onto the sponge allowed the team to measure its height and width, while images captured from above by a second vehicle, Seirios, helped determine its length.
Those dimensions eclipsed the previous record – a colony of the glass sponge Aphrocallistes vastus, found in shallow waters off western Canada, that measured 3.4 meters long, 0.5 meters wide, and 1.1 meters high.
But we don’t really know who our mystery record-holder is. The researchers didn’t collect a sample of the enormous sponge itself, but they did retrieve a smaller specimen from a nearby location that they believed belonged to the same species.
Examining its microscopic skeletal structures, called spicules, revealed that it belonged to a family of glass sponges called Rossellidae. Its exact species, however, remains unidentified.
In fact, these were the only two apparent representatives of the species encountered during the expedition, despite the researchers conducting 18 dives.
Glass sponges get their name from their delicate skeletons, made of silica – the same material that makes up glass. These intricate structures support the animals’ bodies, while providing shelter for other marine organisms.
Like other sponges, they are filter feeders, drawing seawater through their bodies to extract tiny particles of food. In doing so, they can filter enormous quantities of water, playing an important role in the ecosystems around them.
And that leaves one other burning question: Just how long does it take to grow a sponge the size of a minivan?
Actually, nobody knows – not for this sponge, anyway.
But other massive sponges are thought to live for astonishing lengths of time. A 2008 study of giant barrel sponges (Xestospongia muta) suggested that some individuals could be more than 2,300 years old.
Whether the enormous glass sponge has a similarly Ahasuerian lifespan is unknown.
Its species and age remain mysteries, more than a decade after it was discovered.
And in the vast, largely unexplored depths of the ocean, there may be even bigger wonders waiting to be found.
“The largest portion of our planet lies in deep waters, the vast majority of which has never been explored,” NOAA marine biologist Daniel Wagner said in 2016.
“Finding such an enormous and presumably old sponge emphasizes how much can be learned from studying deep and pristine environments such as those found in the remote Papahānaumokuākea Marine National Monument.”
The researchers’ account of the discovery was published in Marine Biodiversity in 2016.
This article was fact-checked by Rachel Garner and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
