How octopuses crawl: New study shows detailed cephalopod movements

For years, scientists have been fascinated by the way octopuses move — fluid, flexible and without the limitations of bones. But observing these complex motions in the extreme conditions of the deep ocean’s midnight zone, where sunlight does not penetrate, has been an enormous challenge.

Now, researchers at Monterey Bay Aquarium Research Institute’s Bioinspiration Lab have developed a new imaging system that records these movements in more detail using a light-field camera system, without disturbing the animals.

The imaging technology, dubbed EyeRIS, relies on an array of microlenses at the front of the camera to capture multiple perspectives in a single shot. It films in low light to observe from a safe distance to avoid physical contact, making sure the animals are undisturbed.

“One of the things that we’re really focused on is how do we observe life in the ocean, but also how do we observe it in such a way that is noninvasive?” said Kakani Katija, MBARI’s principal engineer.

Scientists used EyeRIS to study deep-sea octopus and shared their findings in the scientific journal Nature. The researchers launched the camera using a robot controlled remotely from a nearby ship.

It traveled to the Octopus Garden located off the coast of California in the heart of the midnight zone, around 10,000 feet underwater, where thousands of pearl octopuses gather to brood their eggs.

Studying the animals in their natural habitat allowed researchers to capture behaviors that would be impossible to replicate in a lab.

“EyeRIS allowed us to follow several individuals as they moved, completely unconstrained, in their natural environment,” said Crissy Huffard, a senior research specialist, in a statement. “Our team was able to get 3D measurements of their arms in real-time as they crawled over the rough terrain of the deep seafloor.”

Traditional 3D imaging requires multiple cameras, but EyeRIS captures all the visual data in a single shot, a crucial advantage for working in deep, remote, and dynamic underwater environments.

“For the first time, we can get really detailed measurements of fine-scale movements of an animal body,” Huffard said. “The data that we’ve collected gives us information like the entire surface of the animal — how does the animal’s whole body move and change and deform?”

One of the most intriguing findings was how the octopuses use their arms when crawling across the sea floor, creating “hinge” points — fixed locations along the arm that act like temporary joints during movement. “They’re not moving that hinge point or that contact point all along the arm,” Katija said. “In fact, it’s really just happening at a constrained location.”

By concentrating strain and bend around these fixed points, the octopuses make it easier to control their limbs. “This allows them to have simple, but sophisticated, control of their arms,” Huffard said.

Developed by researchers in MBARI’s Bioinspiration Lab, the EyeRIS camera system (right) enables near real-time three-dimensional imaging and visualization in a compact payload that can be deployed to depths of 4,000 meters (13,100 feet).

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Joost Daniels/MBARI © 2021

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Engineers have looked to octopuses when designing what they call “soft-bodied” robots, which can slink and squirm into confined spaces inaccessible to humans or even more rigid robots.

They have been used in search and rescue operations, manufacturing and even space exploration.

And this study improves our understanding of how octopuses move, and could help reimagine robotics for these and other areas.

MBARI’s innovative EyeRIS camera system collects near real-time three-dimensional visual data about the structure and biomechanics of marine life.

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Courtesy of MBARI © 2022

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In the medical field, for example, soft-bodied robots are used for noninvasive surgery, prosthetics and more.

Beyond its engineering applications, Katija emphasized that EyeRIS offers a new, noninvasive way to study marine life. Rated for use down to more than 13,000 feet, it can be deployed on remotely operated vehicles to study animals from the sea surface to the deep seafloor.

She also stressed the importance of studying these species in their natural, and often vulnerable, habitats. “We’re studying animals in environments that are really threatened thanks to human activities,” she said. “Really understanding these animals in their natural environment is incredibly important before these systems change, and in some cases, irreparably.”