Sleeper Sharks From Thousands of Miles Away Feast on a Sunken Cow

Researchers lowered a dead cow to the bottom of the South China Sea, more than a mile down, and a shark that had no business being in that ocean showed up to eat it. Several of them, actually.

Scientists planted the cow carcass on the seafloor at 1,629 meters depth off the southeast coast of Hainan Island. Deep-sea cameras captured footage of eight Pacific sleeper sharks swimming and feeding around it: the first confirmed sighting of the species in the South China Sea.

Pacific sleeper sharks (Somniosus pacificus) belong in the cold, deep waters of the North Pacific. Their documented range runs from Japan and the Bering Sea to the Gulf of Alaska and as far south as Baja California. The South China Sea is warmer, tropical and considerably farther south than anything in their known range. Nobody put them there. They were already there.

The eight individuals ranged from 1.9 to 5.1 meters in length and all were identified as female. Cameras also captured something behaviorally unexpected: sharks larger than 2.7 meters attacked the carcass directly and aggressively, while smaller ones circled in a cautious, deliberate queue. Deep-sea apex predators, apparently, wait their turn.

The footage also showed distinct eye retraction movements during feeding, likely a protective adaptation. Members of the genus Somniosus lack a nictitating membrane, so instead of blinking, they pull the whole eye back. Which is, by any reasonable measure, a choice.

Researchers note that other deep-sea species, including the megamouth shark, also skew female in the South China Sea, raising the possibility that the area functions as a nursery ground for large shark species.

A range that keeps expanding. An ocean floor we have barely mapped. The cow was bait for the experiment. It turned out to be bait for a much bigger question.

Read the full story at Discover Wildlife, July 23, 2026

Hot Take: Sleeper sharks travel thousands of miles, break every range map on file, then form a polite queue to eat a cow. Apparently even ocean outlaws have manners.