Kleptopredator' Found: Sea Slug Attacks After Prey Has Eaten

A type of brightly colored sea slug has a taste for microscopic marine creatures called zooplankton, and it feeds on them using a method that's never been seen before: It captures quantities in a gulp by using a middleman.

The sea slug's unsuspecting helpers are hydroid polyps — tiny, coral-like animals that live in colonies and gorge on zooplankton. And the sea slug, known as a nudibranch, treats the polyps as living fishing nets, avidly scooping them up and swallowing them down as soon as the hapless hydroids finish their zooplankton supper.

Some animals, such as hyenas, are known for a behavior called kleptoparasitism, in which they wait until an animal kills its prey and then drive the predator away to claim its meal. However, this nudibranch behavior — stealing the predator's feast by swallowing the predator and prey together — is something that was previously unknown, and researchers dubbed it "kleptopredation" in a new study. [Gallery: Jaw-Dropping Images of Life Under the Sea]