There are not many jellyvores in the world, or so scientists have long thought.

Gelatinous sea animals, like jellyfish and ctenophores, have traditionally been regarded as “dead ends” in food webs. Because they are so low in calories (jellyfish are about 95 percent water), it was thought that most predators would not benefit from eating them. But a recent study has identified a new, unexpected jelly-eater: penguins.

Like other warm-blooded animals, penguins have high caloric demands and typically seek energy-dense foods, like fish and krill. In a paper published in Frontiers in Ecology and the Environment, however, an international consortium of scientists has reported that an assortment of penguin species frequently attack jellies as food, a behavior that had not been documented before.

Past studies have found DNA from gelatinous creatures in penguin guano, but researchers thought the seabirds might be accidentally ingesting jellies, said Michael Polito, an assistant professor of oceanography at Louisiana State University who was not involved in the study. That “penguins are specifically targeting gelatinous prey” is a surprising finding, he said.

In the new study, led by Jean-Baptiste Thiebot, a postdoctoral researcher at the National Institute of Polar Research in Japan, teams from five countries monitored four penguin species: Magellanic penguins in Argentina, Adélie penguins in Antarctica, little penguins in Australia and yellow-eyed penguins in New Zealand.