Sharks filmed living in active underwater volcano

When a National Geographic team dropped an 80-pound camera into an active volcano beneath the South Pacific Ocean, they expected to see unique geology and hydrothermal activity. What they didn't necessarily expect to see were sharks -- but that's exactly what their camera picked up, as you can see in the video above.

While most of us only think of volcanoes as fire-spewing mountains above sea level, according to Oregon State University's Volcano World website, about 75 percent of the globe's annual output of magma comes from underwater -- or submarine -- volcanoes. The volcano the National Geographic team explored is called Kavachi and has a summit that's 66 feet, or 20 meters, below the surface of the water near the Solomon Islands.

After the heavy camera was dropped through the volcano's ash cloud, it came to rest 147 feet below the surface, inside the active volcano's caldera -- a pit formed when a chamber previously filled with magma collapses.

Once the camera was brought back aboard and the data was downloaded, the team of researchers cheered as first a sixgill stingray, then a scalloped hammerhead shark and a silky shark swam into view.

"One of the videos from inside the main caldera of Kavachi shows some jellyfish hanging out," team leader and ocean engineer Brennan Phillips said in the comments below the video. "They seem to be there naturally. And then we see some snappers and some small fish...and then sharks start coming after the camera. Sharks are cool in their own right -- all of them are -- but a hammerhead is particularly neat-looking. And they're in there, in numbers, inside the volcano! Now I want to spend years trying to study that and why that is the case."

The researchers want to know how these species could seemingly not be affected by the hot temperatures and acidity of the water -- and what happens to them when Kavachi erupts.

Phillips says in the video, "When it's erupting, there's no way anything could live in there. And so to see large animals like this, that are living -- and potentially they could die at any moment -- it brings up lots of questions. Do they leave? Do they have some sort of sign that it's about to erupt? Do they blow up sky-high into little bits?"

I guess those are questions for next year's Shark Week, eh?