You’re camping in the woods, about to tuck into some salmon you’ve caught when a bear appears. It’s waiting for you to eat your fish, so it can swoop in to eat you.
This is a steal for the bear. For the price of a human, it’s bagged a human-salmon combo meal.
This scenario is hypothetical, but the feeding strategy it illustrates is not, according to a study published Wednesday in Biology Letters. In the report, a team of scientists from Britain and Italy termed the tactic “kleptopredation” and described it not in bears, but in a brilliantly colored sea slug, Cratena peregrina, that’s about the length of a soda can tab and commonly found in the Mediterranean.
These psychedelic slugs, also called nudibranchs, are known to feed on tentacled marine organisms known as hydroids, which are related to corals and sea anemones. They pop the polyps off the hydroids as one might pick a flower off a stalk. But based on lab experiments, the authors of the new paper suggest the slugs prefer to eat hydroids that have just ensnared plankton, a food item nudibranchs aren’t capable of capturing for themselves.
Think of it like wielding a living fishing rod. Or eating a turducken. Whichever your preferred analogy, kleptopredation — using one prey item to obtain another prey item — falls outside ecologists’ traditional classifications of feeding behavior. There’s predation, and there’s so-called kleptoparasitism (when one animal takes food from another animal, like a pack of hyenas stealing a fresh kill from a lion). But kleptopredation is something new.
Patrick Krug, a nudibranch expert at the California State University, Los Angeles who was not involved in the study, said this “steal your meal, and eat you, too” strategy potentially rewrites how ecologists understand food chains. “You usually think of a predator eating a prey item, not eating what the prey item is eating,” he said.
