How to Catch a Jellyfish

Biologist David Gruber dives deep underwater to study all kinds of marine animals. But there’s one creature that time and again gives him headaches: jellyfish. When jellyfish are captured in nets, their squishy bodies break apart. That makes it hard to examine the animals up close. “Jellyfish are fragile,” Gruber says. “If you touch them, sometimes they fall apart.”

To help solve the problem, Gruber worked with a team of engineers to build a device that can trap sea creatures without harming them. The device looks like a claw with five arms. The claw is 20 inches wide when it’s open. A small motor delicately folds the arms shut, encasing jellyfish and squid inside an 8-inch-wide dodecahedron, a 12-sided shape. It’s like a Poké Ball—the tool to catch the beloved monsters in the Pokémon video games—but for marine animals.

Biologist David Gruber dives underwater to study ocean animals. But there’s one creature that often gives him trouble: jellyfish. Jellyfish have squishy bodies. If Gruber catches them in nets, they often break apart. That makes it hard to examine the animals up close. “Jellyfish are fragile,” Gruber says. “If you touch them, sometimes they fall apart.”

Gruber worked with a team of engineers to help solve this problem. They built a device that can trap sea creatures without harming them. The device has five arms arranged into a circular claw. The claw is 20 inches wide when it’s open.

To catch an animal, a small motor carefully folds the arms together. They close to form a container 8 inches wide. The container is a shape called a dodecahedron. That means it has 12 flat sides. The device is similar to a Poké Ball—the tool to catch creatures in the Pokémon video games. But instead of catching Pokémon, it catches jellyfish and squid!

It took years to create the claw, says Robert Wood, an engineering professor at Harvard University. The idea came from one of Wood’s students, Zhi Ern Teoh. He had made a small model of the claw using folded paper. When Wood and his colleagues saw the model, they realized a bigger version of it could be used to capture sea animals. So they got to work!

The engineers first tested a prototype of the claw at the Mystic Aquarium in Connecticut. They tried to catch rubber ducks and vegetables like carrots and celery to see if the device worked underwater. They also tested it on jellyfish and realized the animals got pinched when the claw closed around them. So they equipped the arms with soft rubber edges to protect the animals from getting hurt.

Finally, the researchers attached the claw to a submarine. The device was able to capture and release several jellyfish and squid off the coast of California in waters as deep as 2,300 feet. Next, Gruber and his team want to add cameras and sensors. With these tools, they can catch creatures, study them, and then release them unharmed. It will be especially helpful to study animals in the deep sea—one of the least studied areas of our planet.

“We know so little about the deep sea,” Gruber says. “Right now, we barely have the tools to look at it.”

It took years to create the claw, says Robert Wood. He’s an engineer at Harvard University. The idea came from one of Wood’s students, an engineer named Zhi Ern Teoh. He used paper to fold a small model of the claw. When Wood and his colleagues saw the model, they realized they could make a bigger version of it to capture sea animals. So they got to work!

The engineers first built a test version of the claw. They tried it out at the Mystic Aquarium in Connecticut. First they tried to catch rubber ducks and vegetables to make sure the device worked underwater. Then they tested it on jellyfish. But they realized the animals got pinched when the claw closed around them. So they added soft rubber edges to the arms of the device to protect the animals from getting hurt.

Finally, the researchers attached the claw to a submarine. The sub dove off the coast of California. The device was able to capture and release several jellyfish and squid in waters as deep as 2,300 feet.

Next, Gruber and his team want to add cameras and sensors. That way they can catch creatures and study them inside the container. Then they can release the animals unharmed. The finished device will be especially helpful for studying animals in the deep sea, says Gruber. It’s one of the least studied areas on Earth.

“We know so little about the deep sea,” says Gruber. “Right now, we barely have the tools to look at it.”