A deep-sea video filmed by NOAA ship the Okeanos Explorer captures an ocean floor shark feeding frenzy off the coast of South Carolina – and the bizarre moment a massive grouper slinks in front of the camera with his bounty of a still wiggling, fully intact shark peaking out of his mouth.

It was Dive 07 of the oceanic expedition, and researchers aboard the ship captured the scene using the remotely operated vehicle (ROV) Deep Discoverer, or D2 for short. D2 was skimming along the bottom of the ocean at a depth of around 450 meters (1,476 feet) in search of a small topographic rise that researchers thought was a shipwreck.

At first, a handful of sharks pop in and out of the frame as the ROV floats over a wide array of oceanic rocks, corals, sponges, and invertebrates. Eventually, it comes across a large group of sharks feeding on a 2.5-meter-long (8-foot) dead swordfish lying on the seafloor. In all, at least 11 individual sharks belonging to two deep-sea dogfish species of the family Squalidae were seen gorging themselves on their swordfish smorgasbord of skin and muscle tissue. The smaller and more numerous sharks are the Genie’s dogfish, only first described last year and named after the shark scientist Dr Genie Clark.

And that’s not even the coolest part. The star of the oceanic show casually glides in at around the 1:45 mark. The large bony wreckfish, also known as a sea bass or stone bass, is seen with the tailfin of a dogfish shark slowly wiggling back and forth. Wreckfish can reach a maximum weight of 100 kilograms (220 pounds) and grow to 75 centimeters (2.5 feet) in length with a long lifespan, with some living up to 70 years. 

“[It’s] more evidence really of how these systems work,” an Okeanos team member says in the video. “Wow, I’m going to remember this forever!” 

NOAA reports that the 250-plus-pound swordfish was recently deceased – possibly just a few hours – given the condition of its body and how quickly the sharks were consuming it. Its cause of death is unclear, but it’s possible that it could have died due to age, disease, or injury. No hook or fishing line was visible that would indicate it was a lost catch, however, if the fish was injured the quick work of the sharks would have made it undeterminable. The swordfish presents a unique learning opportunity to understand how “food falls” work in the deep sea. These occur when large pelagic species like whales and swordfish eventually sink to the bottom of the ocean after dying, transferring organic carbon to the deepest parts of the ocean.