Don’t be fooled by the seal’s cute appearance, those beady eyes hold some dark secrets. Researchers have captured footage of an adult gray seal (Halichoerus grypus) drowning a pup and then eating it.

The video was shot by a team of marine mammal behavior experts from Durham University on the Isle of May, a 1.8-kilometer-long (1.1-mile-long) island off the east coast of Scotland.

Over the course of a week in early December 2014, they witnessed the same male individual cannibalizing five different pups. In one instance, shown in the video below, he was seen dragging a pup to a shallow pool, submerging it underwater until it drowned and then proceeding to cannibalize it.

In their study, the team describe how they found a total of 14 pup carcasses in the area with “traumatic injuries,” which they believe were killed by an adult of the same species. At least 12 of these were found partially eaten.

Among the dead seals, the scientists found “corkscrew”-shaped injuries that spiraled down and around their bodies. Seals have previously been found along U.K. shores with these injuries. Due to their shape, they were previously presumed to have been inflicted by boat propellers. However, the researchers believe that all of these instances could instead be linked to seal-on-seal predation.

As New Scientist reports, this display of cannibalism has strengthened the notion that seals are switching their diets from fish and crustaceans to other marine mammals due to rapid changes in their environment.

This isn’t the first time seals have been wrapped up in some grisly and aggressive behavior. Two years ago, they were responsible for wiping out hundreds of porpoises and have also been documented raping penguins.

Cannibalism by a male grey seal (Halichoerus grypus) in the North Sea from Aquatic Mammals on Vimeo.