National Geographic marvels at a recently discovered sea creature named, due to its bizarrely voluptuous curves and clefts, the pigbutt worm:
Such was the case in 2001 when experts from the Monterey Bay Aquarium Research Institute piloted a remotely operated submersible to depths between 2,700 and 7,200 feet off the coast of California. It was there, in the lightless Midnight Zone, named for fact that no surface light reaches these depths, where they came face to face with a translucent, pink blob about the size of a hazelnut.
“It was bigger than most of the small particles that we see down there,” says Bruce Robison, a senior scientist at the MBARI. “As we zoomed in on it with the camera, everybody was remarking, ‘I’ve never seen anything like that before.’”
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At first glance, [Smithsonian marine biologist Karen] Osborn remembers thinking the blob looked a bit like the bristle worms (also known as polychaeta worms) she studied. But there were two immediate problems. First, as adults, bristle worms spend their lives burrowed into the seafloor in tubes of their own creation. And second, even if the strange creature was a larval bristle worm, which are known to float freely in the water column, the animal was at least 10-to-20 times the size of any bristle worm larvae she’d ever seen.
Then, under the microscope, more peculiarities came into focus.
Bristle worm larvae are usually made up of more than a dozen segments, explains Osborn. But the pig butt specimen had a distinct anatomy. It was like a bristle worm took two of its central segments and inflated them like a balloon. The other segments were still there, but scrunched down on the end and less obvious.
That similar-but-different look reinforced the idea that the pigbutt worm was a kind of bristle worm, just one she hadn’t seen before; and that hunch was later backed up by DNA analysis.
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The pigbutt worm likely feeds upon marine snow, fecal pellets, and other detritus that become ensnared in the snot, he explains.
Back at the laboratory, the scientists have also observed that, like many creatures of the deep, pigbutt worms have evolved bioluminescence.