Reef sharks, hammerheads and scalloped hammerheads all swam up to the lens, unbothered by the fact an eruption had taken place shortly before.
The discovery was made in 2015 at Kavachi volcano in the Solomon Islands by National Geographic grantee Dr Brennan Phillips.
How, why and how many sharks are there is one of the world’s enduring marine mysteries and is the focus of a recent National Geographic documentary called Sharkcano.
Marine ecologist Michael Heithaus, from the Department of Biological Sciences at Florida International University, has dedicated the last few years of his career to answer why the apex predators are attracted to volcanoes.
Professor Heithaus, who has studied sharks for the past 25 years, told 9News.com.au he was blown away by Dr Phillips’ discovery, which occurred by happenstance.
“I thought it sounded like a sci-fi movie. It’s an amazing find,” Professor Heithaus said.
“It just demonstrates how adaptable sharks are.
“Extreme environments are something they can clearly handle; whether it’s a volcano or surviving thousands of metres underwater.
“It’s really not yet known why they are there. It could be something to do with reproduction, or who knows what else is living in there… maybe they’re just sniffing out a meal.”
Further studies into the sharks have been hampered by the fact Kavachi is so active, which begs the question: how do the sharks survive in an active crater, 18 metres below the surface, where temperatures reach near-boiling point?
Sharks have a cluster of pores on their snout called the ampullae of Lorenzini, which Professor Heithaus believes can detect changes in the earth’s magnetic field – allowing them to swim to safety before an eruption occurs.
This mysterious “sixth sense” may also help them hunt and sniff out other volcanic islands.
“It looked like the sharks in the volcano were used to dealing with eruptions,” he said.
“You would think it’s dangerous but studies have shown us they can detect approaching hurricanes and cyclones, so they may be able to detect when something bad is about to happen and move out of the way.”
While his research is still in progress, Professor Heithaus said the correlation between sharks and volcanoes is undeniable.
His studies have taken him to the rugged shores of Réunion Island, which is home to an active volcano called Piton de la Fournaise.
Sharks are so abundant there, swimming was made illegal in 2013.
Eleven people have lost their lives in attacks since 2011, mostly by bull sharks.
In this instance, Professor Heithaus believes the bull sharks are taking advantage of the fact sediment washes down from the volcano’s slope.
The cloudy waters make an ideal hunting ground for the “smart” predators.
The extreme habitat ironically provides a safe-haven for them, Professor Heithaus said.
“The biggest threat to sharks by far is overfishing. There are just too many being caught and that is being driven by the demand for fins and shark meat,” he said.
“You’re not going to go fishing around a volcano and probably some of the bigger sharks, who are predators, will be less inclined to go in there.
“We may not know exactly why they are there but the fact we saw so many in a fairly short window of time, suggests it is an importance place to those sharks.
“If it wasn’t a great place to live they probably wouldn’t be there… who doesn’t like a hot tub?”
Source: 9News
