A lot of crazy stuff happens in the ocean. Most of it, of course, we don’t see. But every now and then, thanks to the wonders of research, we’re afforded a view of something absolutely incredible. Case in point: a shark feeding frenzy on a swordfish, accented nicely by a sneaky grouper coming in for a shark steak.
The scene played out before the cameras on a remotely operated vehicle called the Deep Discoverer (D2), a piece of equipment on the NOAA ship Okeanos Explorer. It was the seventh dive on the Windows to the Deep expedition, and it left the viewers aboard nearly speechless. “You can’t plan on seeing these kinds of things, especially in the deep ocean,” wrote Peter J. Auster of Mystic Aquarium and University of Connecticut in the mission log. “It is simply serendipity; by just spending enough time underwater and being prepared for the unexpected, you can stumble across scenes that will replay in your mind’s eye over and over for a lifetime.”
As the D2 ran up a small rise that was originally thought to be a shipwreck, a few sharks appeared in its camera. Soon, in the dim reaches of the vehicle’s lights, the operators noticed what appeared to be a feeding frenzy. A swordfish, measuring around eight feet in length and likely weighing up to 250 pounds, was the main attraction, and at least 11 sharks were gorging on it.
According to the researchers, the swordfish had only been dead for a few hours. “The cause of the death of this majestic animal is unclear, perhaps owing to age, disease, or some other injury,” they wrote. “There was no visible hook or trail of fishing line suggesting this was a lost catch. However, any type of injury would have been masked by the massive damage caused by hundreds of shark bites.”
Most of the sharks in the video are called Genie’s dogfish, a species first described in 2018. Two of the larger ones are roughskin dogfish. Both species generally hang out in deep waters—from 700-2,000 feet—along the continental margin.
But the feeding frenzy, as incredible as it was, didn’t prove to be the only part of the story. Seemingly out of nowhere, a large grouper takes advantage of the sharks’ target fixation and swallows one nearly whole. “Using the ROV for cover, it demonstrated the ability of large predatory fishes to feed on smaller sharks,” the researchers explained. “The wreckfish appears unable to feed on the swordfish directly itself, but by joining the sharks, it was able to feed on an animal that was.”