You'll Never Guess What's Living Inside This Underwater Volcano

You're likely to see unique marine creatures while visiting Hawaii and other Pacific islands. If you head to the Solomon Islands, you're in the land of Kavachi, an underwater volcano known for near-constant eruptions and unusual ecosystems. Though its acidic environment can't support most life forms, a few fascinating creatures have made it their home. Kavachi's zooplankton and reef fish have captivated scientists, and its sharks have generated excitement in the broader population as well. In 2015, a research team found scalloped hammerhead sharks (Sphyrna lewini) and silky sharks (Carcharhinus falciformis) living in the volcano's submerged crater, near a vent that spurts lava. At a rare moment when the volcano wasn't erupting, they saw the sharks through a baited camera placed more than 150 feet below the water's surface. Some sharks that lunged at the camera seemed to hail from even deeper parts of the crater. These aren't the world's most dangerous sharks, but they aren't average specimens. Experts think they're mutants.

In a paper published in the journal Oceanography, the researchers theorize that these sharks have evolved to flourish in the crater's harsh environment, a process that involves mutation. They also argue that this strange microcosm suggests "the types of animals that have survived past major changes in ocean chemistry, and those that will thrive in future ocean conditions." In other words, the researchers found mutant volcano sharks that behave as if they're traveling through time. These rulers of the "sharkcano," as Smithsonian Magazine dubbed it, are the perfect subject for a sci-fi horror nature documentary. But first, scientists want to learn what other abilities these sharks possess, such as sensing upcoming volcanic eruptions. 

Shark jaws are impressively strong, so the Kavachi expedition researchers used robots to explore the volcano. This technology showed how strange the environment inside the crater is. "We found a huge drop in the surface pH levels, water temperatures ten degrees higher than normal, and we learned Kavachi is a strong greenhouse gas emitter," Matthew Dunbabin, one of the researchers, said in a National Geographic interview. "These learnings are now driving the development of new experiments for the next trip, such as trying to quantify the shockwaves close to the vent to understand the tolerance of the pelagic fish and sharks that are living around this volcano." Yes, you read that right: Scientists are designing more robots to see how mutant volcano sharks evolved to withstand explosive pressure changes.

The story gets even cooler. According to Brennan Phillips, an ocean engineer on the research team, even the toughest sharks shouldn't thrive in this volcano. Despite the odds, they tolerate its heat, acidity, and uncomfortably cloudy water. "None of these things are good for fish. Whether they're good for sharks, that's up for debate. Yet we saw sharks that in between eruptions are darting in and out between the clouds of the plume. So that's a lingering question mark," he told National Geographic. Phillips expects that recent advancements in robotics will get scientists closer to the answers on future expeditions: "The door is open for many people to make cheap robots, whether they fly, swim, or drive. We're seeing great video and data from things that scientists haven't been able to do before. It's really exciting to be part of that."