Jellyfish, despite being such simple creatures without brains, are able to explore the depths of the ocean with ease. All they can really do is swim, sting, eat, and breed, yet they can do something that even humans, with all our sophistication, cannot.
What if we could use jellyfish to explore the oceans and report back to us? Well, researchers at Caltech have made this a possibility through the creation of biohybrid robotic jellyfish. By augmenting jellyfish with electronics and a prosthetic “hat,” these creatures can carry small payloads and swim in a more streamlined manner.
The work, conducted in the lab of John Dabiri (MS ’03, Ph.D. ’05), the Centennial Professor of Aeronautics and Mechanical Engineering, builds on his previous work augmenting jellyfish. His goal with this research is to use jellyfish as robotic data-gatherers, sending them into the oceans to collect information about temperature, salinity, and oxygen levels, all of which are affected by Earth’s changing climate.
“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,” Dabiri says. “Our goal is to finally move that needle by taking an unconventional approach inspired by one of the few animals that have already successfully explored the entire ocean.”
Dabiri’s lab previously implanted jellyfish with an electronic pacemaker to control their swimming speed. The researchers found that when the jellyfish swam faster than their usual pace, they became even more efficient. Interestingly, a jellyfish swimming three times faster than normal only uses twice as much energy.
The researchers added a “forebody” to the jellies this time, which sits atop the mushroom-shaped part of the animal’s bell. The forebody serves as a hat-like structure that makes the jellyfish more streamlined and provides a place to carry sensors and other electronics. The devices were designed by a graduate student and lead author, Simon Anuszczyk.
The researchers designed 3D-printed forebodies to streamline the bell and reduce drag, which improved the swimming performance of a jellyfish robot. They also managed to balance the buoyancy of the robot and keep it swimming vertically.
To test the robot’s swimming abilities, a massive vertical aquarium was constructed at Caltech’s Guggenheim Laboratory. They built a vertical aquarium to test the jellyfish’s swimming abilities and gather data on oceanic conditions far below the surface.
“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 says. “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.”
According to the research, it seems that these robotic jellyfish equipped with a combination of the swimming pacemaker and forebody can swim up to 4.5 times faster than an all-natural jellyfish while carrying a payload. What’s more, the total cost of these jellyfish is only about $20 each, which makes them an attractive alternative to renting a research vessel that could cost more than $50,000 a day to run.
“By using the jellyfish’s natural capacity to withstand extreme pressures in the deep ocean and their ability to power themselves by feeding, our engineering challenge is a lot more manageable,” Dabiri adds. “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.”
Future work may focus on further enhancing the bionic jellyfish abilities. Currently, they seem to be limited to swimming faster in straight lines for deep ocean measurement purposes. They can also be made steerable, so they can be directed horizontally as well as vertically. This would open up even more possibilities for their use.
Journal reference:
- Simon R Anuszczyk and John O Dabiri. Electromechanical enhancement of live jellyfish for ocean exploration. Bioinspiration & Biomimetics, 2024; DOI: 10.1088/1748-3190/ad277f