Scientists Say: Kleptopredation

Some predators take advantage of this buy-one-prey, get-one-free meal deal

a colorful sea slug that engages in kleptopredation

The pilgrim hervia sea slug (Cratena peregrina) grazes on hydrozoans, preferring those that have just had a meal themselves. This is one example of a meal-stealing hunting strategy called kleptopredation.

imageBROKER/Frank Schneider/Getty Images Plus

Kleptopredation, (noun, “KLEP-toh-pre-DAY-shun”)

Kleptopredation is when an animal hunts prey that has recently hunted and eaten its own prey.

The root word “klept-” means theft. So, kleptopredation describes a predator that hunts prey and steals their last meal. Scientists first noticed this double-dipping hunting strategy in 2017.

Some animals steal prey from others. Scientists have known that for some time. For example, hyenas may gang up against a lion to steal a hunted gazelle. This practice is called kleptoparasitism. But the hyenas eat only the gazelle, not the lion. That’s what sets kleptopredation apart. The hunter eats both its own prey and the prey’s last meal.

Some predatory sea slugs use this approach. Take the pilgrim hervia (Cratena peregrina). These electric-blue and tangerine-colored sea slugs graze on colonies of little polyps called hydrozoans. But they’re a little picky. The sea slugs prefer eating polyps that have just had a meal themselves. Hydrozoans are predators that catch and eat plankton. So, the sea slug chows down on plankton-stuffed polyps in this two-for-one meal deal.

Scientists have now seen other animals use this buy-one-get-one-free scheme, too. For instance, some jumping spiders eat mosquitoes. And they seem to prefer catching mosquitoes that have just had their own blood meal.

In a sentence

Some predatory sea slugs use kleptopredation to eat both predator and prey.

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Katie Grace Carpenter is a science writer and curriculum developer, with degrees in biology and biogeochemistry. She also writes science fiction and creates science videos. Katie lives in the U.S. but also spends time in Sweden with her husband, who’s a chef.

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