So You Decided to Build a Jellyfish Treadmill – Pasadena Now


Timelapse of a jellyfish inside a treadmill.Credit: California Institute of Technology

John Dabiri (PhD ’05), Centennial Professor of Aeronautics and Mechanical Engineering at Caltech, has studied jellyfish through a variety of lenses for many years. He has sought to understand their energy-saving movement strategies so ships can mimic their efficient forms of propulsion. He discovered a link between the hydrodynamics of swimming jellyfish and blood flow in the human heart, which could help find indicators of heart disease.

Starting in 2019, Dabiri’s research focus shifted to trying to enhance jellyfish with electronics that could collect data on how the ocean responds to climate change. But before we embarked on this project, we knew we would need a larger jellyfish tank. It’s something bigger.

To turn jellyfish into deep-sea scientists, Dabiri first needed to equip them with the necessary small electronics so they could swim for several days. And to see if that’s possible, scale from the 6-foot-tall container in which you were observing the jelly to a nearly 20-foot-tall container that can house a “jellyfish-his-treadmill” with controlled flow. He realized he needed to up. The amount of water that allows the animal to swim in place for as long as necessary.

“We found a space inside the Guggenheim Institute for Aeronautical Research building that looked like an elevator shaft where they had forgotten to put the elevator in,” Dabiri recalls. “That idea became this big 40,000-pound structure of his that is suspended above an area where researchers can go underneath to collect certain measurements.”

Dabiri and his lab members take pride in building their own equipment, but this project was beyond their expertise. So he consulted an expert. The specialist is a commercial aquarium company known for manufacturing large aquarium displays for customers including Las Vegas resorts and wealthy homeowners. A team of civil engineers helped design the support structure for the nearly 100-year-old wall-supported tank.

Caltech facility staff coordinated the delivery and installation, which was no easy task. Dabiri said the team threaded a block of fiberglass and plexiglass through the lab door with about a quarter-inch to spare, then stacked the components like Legos and bolted everything together. It is said that he did.

“I remember when I first filled up the tank, there was a moment where I actually started hearing crackling,” he says. “I was under the tank with one of the contractors, so of course we rushed out. In the end, it turned out that it was just a normal sinking of the tank material, but the engineering was very accurate. This highlighted the importance of what we must do.”

As a final test, a scuba-certified graduate student jumped into the tank to see if in the future it would be possible for humans to enter the tank to repair parts or retrieve fallen items. “What happens if someone drops their iPhone?” Dabiri says. “This tank is 20 feet deep, so we had to come up with a procedure to allow certified divers to go inside and retrieve the items.”

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The 3,600-gallon tank currently in operation at the Guggenheim is equipped with two motors that control the flow of water to simulate the upwelling and descent of the ocean. Filter systems and temperature controls keep animals healthy. Rotating vanes at the bottom of the tank maintain an even flow of water.

Jellyfish treadmills have already been published in scientific papers. A recent study published in the journal Bioinspire & Biomimetics implanted both an electronic device to speed up the jellyfish’s natural pulsating motion and an additional hat-like precursor that rests on the jellyfish’s bell. The results of an experiment monitoring jellyfish that have been exposed to jellyfish are summarized. The anterior device, designed by graduate student and first author Simon Anuszczyk (MS ’22), is intended to make the jellyfish more streamlined and provide a place to install data-gathering sensors and electronics. Dabiri and Anuszczyk showed that jellyfish equipped in this way can swim up to 4.5 times faster than unenhanced jellyfish while carrying payload.

“I remember when I first filled up the tank, there was a moment where I actually started hearing crackling.” — John Dabiri

Anuszczyk is working on a computer vision algorithm that recognizes the location of each jellyfish with its progenitor in an aquarium and tracks it over time. “If the animal speeds up or slows down a little, you have to increase or decrease the flow in the tank to keep the animal in place on the treadmill,” Dabiri explains. This allows continuous monitoring. “Simon has come up with a really clever AI-based way to do that using a camera looking at the animal.”

New applications like this one can help simulate long-distance trips to deep ocean waters, like the Mariana Trench, which is about 11 miles deep. “We hope to be able to keep jellyfish swimming in the treadmill for up to three or four days, which is about the same amount of time it takes for jellyfish to swim down from the ocean surface into an ocean trench,” Dabiri said. says. I would add.

Dabiri believes the tank could have many other research applications. For example, he has studied brine shrimp. Brine shrimp are small creatures with a swimming behavior similar to marine plankton that migrate vertically in large groups at sunset each day. Understanding the dynamics of the water flows produced by plankton each day can be important for understanding carbon sequestration on the ocean floor and bringing oxygen and nutrients to the surface. Experimenting with flow phenomena like this is much easier on a vertical treadmill than in a 3-foot aquarium.

“I’m excited to have been able to do that. That’s one of the reasons I’m glad to be back here at Caltech,” he said, joining the institute in 2019 after spending some time at Stanford University. Mr. Dabiri, who returned to , says: “I can come up with crazy ideas and put them into action.”

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