For animals that drift through the sea without the benefit of eyesight, jellyfish have managed to survive remarkably well. In fact, in areas where overfishing and habitat destruction have reduced fish populations, jellyfish are now becoming the dominant predators.

It turns out that jellyfish, despite their sluggish looks, are just as effective at hunting and catching meals as their competitors with fins. They may not move as quickly, but in a study published in the journal Science, researchers found that many jellyfish use their body size to increase their hunting success. With their large, watery bodies and long tentacles, they conserve energy by letting currents guide them into their prey, said José Luis Acuña, an author of the paper and a biologist at the University of Oviedo in Spain.