Researchers have used very small electronic devices to make jellyfish stronger and faster. The scientists say they developed these electronic jellyfish in the hopes of sending them to study and explore the world’s oceans. A report on the experiment was published in the journal Science Advances. Jellyfish are unusual creatures. They move through seawater by contracting, or reducing the size of, their muscles. For the experiment, the researchers put an electronic device, about 2 centimeters in length, inside a moon jellyfish, a common kind of jellyfish. The researchers said the device caused the creatures to move their bodies more often. They swam around three times faster than usual.