A 7-foot shark was eaten by an even bigger shark, researchers suspect

A 7-foot pregnant shark appears to have been eaten by an even larger shark in what researchers believe is the first such evidence of an ocean predator becoming prey.

Researchers caught the porbeagle shark off Cape Cod, Massachusetts, in late October 2020 and attached two tracking tags — one mounted on the shark’s dorsal fin to broadcast its location and a second tag, called a pop-off satellite archival tag (PSAT), which measures the temperature and depth of sharks in the ocean, the scientists wrote in a paper published Tuesday in the journal Frontiers in Marine Science.

The PSAT is designed to detach from the shark after about a year, but in this case the device came off after about five months near Bermuda.

“Something had gone very wrong,” Brooke Anderson, one of the researchers, told NBC News.

Data collected from the shark showed that in the days before its limb broke off, its diving patterns had become erratic.

His temperature readings also rose despite swimming at a deep enough depth that would have made the readings much cooler, according to the study.

Using this data, the researchers determined that the tag had spent several days in the stomach of another animal.

Mammals such as orcas were ruled out due to warmer temperature readings, so the scientists focused on endothermic sharks.

“The data presented in this study are, to our knowledge, the first evidence of predation in a porbeagle and provide new insight into interspecific interactions for this large, globally vulnerable shark species,” the study said.

The researchers hypothesized that the ocean’s apex predator fell prey to a larger shark, of which they say only two are large enough to eat a pregnant 7-footer: the white shark and the basking mako.

James Sulikowski, director of the Oregon Coastal Naval Experiment Station at Oregon State University, who also participated in the research, told USA Today that the study shows that the ocean still contains many mysteries that scientists want to solve.

“It makes us want to study more and learn more about how susceptible other large sharks are to being eaten and who is top dog out there,” he said.