Quartz describes it as "theft-meets-murder-in-a-meal," but we think it sounds more like nature's turducken. In a study published Wednesday in Biology Letters, marine biologists from the Institute of Marine Sciences at the University of Portsmouth in Britain describe a heretofore unobserved method of eating and coined a new term for it: "kleptopredation." The concept of kleptoparasitism has been around for a while; it's what hyenas do when they scare off an animal that's just killed its prey in order to steal the meal, Live Science explains. In kleptopredation, on the other hand, an animal waits until its prey has finished eating then just straight-up eats its prey and its prey's prey, which is currently sitting in its prey's belly.
The marine biologists observed kleptopredation in a type of sea slug called a nudibranch. The study found that in 14 out of 25 cases, nudibranchs chose to eat hydroid polyps, its normal prey, while the polyps still had a belly full of zooplankton, their typical prey. Because the zooplankton inside the polyps accounts for about half of nudibranchs' diet, researchers believe the sea slugs actually favor consuming plankton rather than the polyps themselves, which nudibranchs appear to be using "as living fishing nets." Researchers believe other marine organisms are likely using kleptopredation as well, likely because it increases their nutrition intake. (This sea slug does something incredibly unusual.)