Using stereo cameras and detection algorithms, Mesobot analyzes the movements of its subjects and follows them. Yoerger and his colleagues demonstrated the robot’s capabilities in Monterey Bay at a depth of 650 feet, as it detected and then pursued a hunting jellyfish. More impressive still, he surreptitiously followed for half an hour a fragile animal called larvacean, which looks like a tadpole and builds a giant “house” of mucus to filter its food. (The robot ended up disrupting the extremely sensitive exterior structure of the house, but the interior structure of the house and the animal itself remained intact.) Based on their tests, the team believes the robot could operate for more than 24 hours and reach depths of 3,200 feet.
At the moment, Mesobot cannot collect animals, but in the future, he could use a suction system to catch them. Just observing sea creatures with a camera won’t tell you what they ate, for example, and therefore where they fit in the food web – you would need a dissection for that. If you want to study their physiology, you also need a physical specimen. “The idea would be to follow an animal for a while and then catch it. I think it’s totally doable, ”Yoerger says.
Mesobot may look like a big AirPods case, but compared to other crewed submersibles and ocean robots, it’s actually quite compact. Perhaps the most famous of all is Alvin, which the Woods Hole Oceanographic Institution also operates. It weighs 45,000 pounds and can only be launched from a specific vessel. Mesobot’s smaller size means it’s cheaper to build and more easily deployable, which will likely open up the platform to more researchers. “It’s another big win,” says Singh of Northeastern University. “He doesn’t need all that extra gear – big winches, big ships. “
Scientists have long known that species perform a daily vertical migration, but until now they had to study it by capturing them at different depths or using sonar to determine where they congregate at any given time. After all, it’s not like you can slap a tracker on a jellyfish or larva to monitor its movements in fine detail. “We have so few observations on a lot of fish,” says Luiz Rocha, fish curator at the California Academy of Sciences, who studies reefs in the Twilight Zone but was not involved in this new work. “We don’t even know how they swim, let alone how they eat or how they reproduce.”
And scientists don’t have a great idea of how the different species that travel in intermediate waters interact; for example, which predators follow their prey along the water column? Do the animals migrate in tight schools or in a more dispersed fashion? Or, how could rising ocean temperatures influence the way a given species migrates, and could this in turn influence others in its food chain? Oceanographers could try to follow them with submersibles, but something less stealthy than Mesobot would likely scare off all subjects. “But if you have a robot that can stay submerged for up to 24 hours and follow a fish or a group of fish the entire time, then you can think about studying these phenomena,” says Rocha.
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