Earth’s oceans are—like space—a largely unexplored frontier. Relatively few humans have explored either place, using specialized life-support equipment. Unlike space, however, the oceans also have other beings that can explore them: jellyfish. They can head to places underwater that humans can never go. That makes them interesting candidates for autonomous ocean exploration.
Jahn Dabiri, a researcher at Caltech, is modifying these creatures to create biohybrid robotic jellyfish. These cyborg jellies do what they’ve done since time immemorial: swim, eat, sting, and breed. But, with a few enhancements—including a little electronics pack and a prosthetic hat—these little guys now have enhanced swimming capabilities. The idea is to use the cyborg jellyfish as data-gathering robots. They will swim the ocean to collect information about temperatures, oxygen levels, and salinity. Climate change affects all these factors. This is important as we seek to understand how the buildup of carbon dioxide could affect the oceans.
“It’s well known that the ocean is critical for determining our present and future climate on land, and yet, we still know surprisingly little about the ocean, especially away from the surface,” said Dabiri. “Our goal is to finally move that needle by taking an unconventional approach inspired by one of the few animals that already successfully explores the entire ocean.”
It may seem a little odd to co-opt jellyfish into doing science data gathering, but it’s not a new idea. These creatures inspired Dabiri to try creating a mechanic robot that swam like one. The idea worked, sort of. But, the robotic one never did swim as well as the real thing. So, eventually, Dabiri decided to, in essence, recruit live ones for further experiments.
Dabiri and colleagues first implanted electronic pacemakers into jellyfish to control their swim speeds. When that worked, they added an additional piece to the jelly, called a forebody. It looks like a little hat that sits atop the jelly’s body. The team had to do some work to adapt it. Eventually, they came up with a model that works with sensors and other electronics.
“Much like the pointed end of an arrow, we designed 3D-printed forebodies to streamline the bell of the jellyfish robot, reduce drag, and increase swimming performance,” team member Simon Anuszczyk said. “At the same time, we experimented with 3D printing until we were able to carefully balance the buoyancy and keep the jellyfish swimming vertically.”
After much experimentation, the team was ready to test their cyborg partners. They built a three-story aquarium at Caltech for the tests. Why so big? “In the ocean, the round trip from the surface down to several thousand meters will take a few days for the jellyfish, so we wanted to develop a facility to study that process in the lab,” Dabiri said. “Our vertical tank lets the animals swim against a flowing vertical current, like a treadmill for swimmers. We expect the unique scale of the facility—probably the first vertical water treadmill of its kind—to be useful for a variety of other basic and applied research questions.”
A biohybrid jellyfish descends through the three-story tank in which swimming tests were conducted. Credit: Caltech
The results are interesting. Testing showed that a cyborg jellyfish carrying an instrument payload swims up to 4.5 times faster than a “naked” one. And, they are hardy creatures that don’t seem to mind the work at all. “Jellyfish are the original ocean explorers, reaching its deepest corners and thriving just as well in tropical or polar waters,” Dabiri says. “Since they don’t have a brain or the ability to sense pain, we’ve been able to collaborate with bioethicists to develop this biohybrid robotic application in a way that’s ethically principled.”
The cost of a cyborg jellyfish is pretty cheap, compared to highly expensive ocean-going instruments. The total expense comes to about $20 per jellyfish, according to Dabiri. A research vessel with similar capabilities can cost upwards of $50,000. Of course, the jellyfish have only been tested in a relatively shallow area. For jellies to be sent to greater depths, there’s more work to be done on their instrument packs. “We still need to design the sensor package to withstand the same crushing pressures, but that device is smaller than a softball, making it much easier to design than a full submarine vehicle operating at those depths,” said Dabiri. “I’m really excited to see what we can learn by simply observing these parts of the ocean for the very first time.”
Dabiri’s work doesn’t cover any space applications. However, reading about these cyborgs does invoke thoughts of using similar technologies at other worlds. We can’t send cyborg jellyfish to Europa, really. But, maybe instrument designers can take a cue from their enhanced abilities to come up with advanced swimmers to ply the salty oceans of that distant moon. Who knows what they might find—and all thanks to some jellyfish research partners right here on Earth.
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