Ancient ‘Bobbit worms’ leaped from under seafloor to snag prey and drag it beneath the sand: study

Leaping out of the seabed like something from a horror flick, the ancient Bobbit worm — named for infamous, penis-lopping Lorena Bobbitt — snatches an unwitting fish as it swims by and drags the wriggling, hapless creature underground for consumption.

Known generically as sand strikers, these carnivorous, stealth predators can reach 10 feet long, though they’re less than 2 inches in diameter. They live entirely under the seafloor, absorbing oxygen through their skin.

Researchers believe they have found fossilized lairs belonging to the worm’s predecessor — an ancient ancestor that lived 20 million years ago — in northeast Taiwan, according to a study published Thursday in the journal Scientific Reports.

The so-called trace fossils are “geological features such as burrows, track marks and plant root cavities preserved in rocks, which allow for conclusions to be drawn about the behavior of ancient organisms,” Nature explained in a press release.

Worms and other soft-tissue marine animals don’t leave bones, so the only way to know whether they’ve been there is by studying the remnants of their activity, researchers at Simon Fraser University in British Columbia said.

The “very, very distinctive” fossils left by the ancient Bobbit worm were “like nothing we’ve ever seen before in the rock record,” study co-author and Simon Fraser earth sciences professor Shahin Dashtgard told CBC News.

National Taiwan University geosciences professor Ludvig Löwemark and Japan’s Kochi University biological sciences professor Masakazu Nara, two of the study’s co-authors, found these ancient clues in a 20 million-year-old sandstone formation in Taiwan’s Yehliu Geopark and Badouzi promontory while they were seeking traces of other marine animals.

They studied 319 specimens preserved within layers of a seafloor that had been formed during the Miocene era, reconstructing an L-shaped burrow about 6 feet long and less than 2 inches wide.

“I was fascinated by this monster burrow at first glance,” grad student Yu Yen Pan, now a PhD student at Simon Fraser, said in a statement. “Compared to other trace fossils which are usually only a few tens of centimeters long, this one was huge; two-meters long, and two-to-three centimeters in diameter. The distinctive, feather-like structures around the upper burrow were also unique, and no previously studied trace fossil has shown similar features.”

The analysis of the burrow’s makeup did not match that of other marine animals, Löwemark told Gizmodo.

“In the beginning, we were firmly convinced it was a very fancy shrimp burrow,” Löwemark told Gizmodo. “And then, after talking to some other experts, we were leaning towards this bivalve hypothesis. But in the end, we became more and more convinced that it’s actually a Bobbit worm that made this trace.”

The discovery sheds a rare light on the hunting behavior of this ancient invertebrate, Pan told CBC News, as well as giving a “rare glimpse” into the behavior of these creatures under the seafloor, said Nature.