Sharks are terrifying creatures — they also happen to be magnificent ones that hold many secrets of life itself. For instance, did you know that sharks can detect changes in a magnetic field? It is this same sensitivity that perhaps helps some sharks even find their way to underwater volcanoes, where molten lava is highly magnetic. This is the subject of National Geographic’s latest special in its Sharkfest line of programming, ‘Sharkcano’.
In 2015, a team of scientists — and subsequently, everyone else in the world — was shocked to learn that there are sharks that live in the burning waters near an underwater volcano. A group of scientists surveying Kavachi, a very active volcano 60 feet below the ocean’s surface near the Solomon Islands, made a map of Kavachi’s peak to learn as much as possible about the chemical plumes, geology and biology of the volcano. However, they were stunned to discover that there are two species of shark living in the hot, highly acidic waters within the crater. The sharks were observed with the use of disposable robots, underwater cameras and National Geographic’s deep-sea Drop Cam.
On top of the volcano-dwelling silky and hammerhead sharks, the team was also psyched to see a Pacific sleeper shark swimming near Kavachi. These enigmatic fish are normally found in the North Atlantic, the North Pacific and around Antarctica, but they’ve never been seen near the Solomon Islands before.
Kavachi is one of over 400 volcanoes in the Pacific basin, part of what is known as the Ring of Fire. The Pacific plate is the world’s largest tectonic place, a piece of the Earth’s upper crust pulling away from, grinding against, and crashing into other plates in a slow but volatile geologic evolution of the planet. This movement, plate tectonics, is what generates volcanoes and earthquakes along the boundaries between plates — 90 percent of the world’s earthquakes occur along the Ring of Fire.
Divers who have tried to go near to the crater when it is not erupting have suffered acid burns or backed away simply because of the heat. But in this inhospitable environment, there are numbers of hammerhead and silky sharks, hanging around and going about their business. The baffling question, of course, is why sharks are attracted to volcanoes.
There are many theories to this — the food-rich environment around a volcano makes it an area where sharks can thrive. However, an experiment by Dr. Michael Heithaus and his team as seen in ‘Sharkcano’ shows there is another reason that sharks are attracted to volcanoes. The team placed strong artificial magnets on the seabed to see if sharks were attracted to the magnetic field. What they discovered was that hammerhead sharks and nurse sharks were not only attracted to them, but the latter also tried to eat them. The ocean floor soon got agitated by all the sharks that had swum to the area.
One thing that is for certain is that there is more to be learned about marine life and especially sharks. Many of these creatures live in precarious conditions and the more answers we get, the more questions arise.
‘Sharkcano’ airs on National Geographic on July 21 at 10/9c.