It’s tough for marine biologists to study deep sea creatures in their natural habitat.

Jellyfish and squid that live a mile or two underwater dwell beyond the range of scuba-diving scientists, who must rely on submarines to explore the near complete darkness at those depths. Once in a while, detritus samplers and other collection tools attached to submersibles can capture the diaphanous animals. But the delicate creatures are at risk of getting stuck in the sampler or destroyed on their way to a lab on dry land.

That’s why David Gruber, a marine biologist at the City University of New York, and a team of engineers are developing soft robots capable of gently grasping live jellyfish and studying them without harming the specimens.

“I always felt that it was a little strange for me as a marine biologist to have to kill the animals that I love and study,” Dr. Gruber said. “I wanted tools that were more gentle, that were able to grasp jellyfish but not hurt them, and that would allow me to swab the creatures and do different things.”

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To create a robot strong enough to work in the deep sea, yet gentle enough to handle gelatinous jellyfish that are about 95 percent water, the scientists came up with a six-fingered gripper that could open and close around the animals. They described their design in the journal Science Robotics on Wednesday.