When two of nature’s most powerful and extreme forces – sharks and volcanoes – combine we get a “sharkcano”. “Sharkcano” is a National Geographic documentary that explores sharks that live and hunt around underwater volcanoes. The active Kavachi volcano 60 feet below the ocean’s surface in the Solomon Islands is being called a sharkcano, because scientists found sharks within its crater. The volcano projects a masterful display of phreatomagmatic eruptions and the volcano’s hot magma hits the water of the ocean.
‘Sharkcano’ WAS EXCELLENT! This 45-minute-long documentary consists mainly of Dr. Michael Heithaus in search of the mysterious connection between sharks and volcanoes.
The special starts on Réunion, a volcanic island where Bull Sharks are commonly found. They have small eyes that make them less reliant on sight and more on smell for hunting. It was very interesting to see this cage dive! In the Bahamas, scientists conduct controlled underwater magnet tests on sharks. The result is jaw-dropping.
The majority of ‘Sharkcano’ is focused on answering the question of why sharks are so attracted to volcanos. I won’t give away all the details but you need to check it out for yourself. It is a must-see!
Let’s start dissecting!
Do sharks have electroreceptors?
Yes! Ampullae of Lorenzini are electroreceptors that allow sharks to detect electric fields. They are a visible network of mucus-filled pores around the head and on the underside of sharks. The ampullae of Lorenzini can help a shark sense its prey by detecting the electrical fields generated by activities of the prey.
Can sharks detect magnetic fields?
Yes! In ‘Sharkcano’, Dr Michael Heithaus and his team placed strong artificial magnets on the seabed to see if sharks were attracted to the magnetic field. They learned that hammerhead sharks and nurse sharks were not only attracted to them, but the nurse sharks also tried to eat them! There were at least 12 hammerheads and another dozen nurse sharks around the area.
Why are sharks attracted to volcanoes?
Scientists believe that sharks navigate (like a GPS) by sensing Earth’s magnetic field or more specifically volcanic rock magnetic fields.
Dr. Heithaus says volcanic islands are attractive hot spots for sharks as they tend to have nutrients flowing into the water providing the basis of food chains.
Dr. Heithaus also mentioned that the ampullae of Lorenzini may be able to detect changes in the earth’s magnetic field thereby allowing sharks to swim to safety before an eruption occurs. This mysterious “sixth sense” may also help them hunt other volcanic islands.
Some sharks were found within volcanic craters of Kavachi! The scientists in ‘Sharkcano’ mentioned that sharks may like the warm water caused by eruptions in order to (1) get energy to feed, (2) digest optimally, or (3) speed up reproduction. Moreover, there is good evidence that there are sharks living in other submarine volcanoes.
Learning how sharks navigate may help scientists understand where they go and better protect these areas, many of which are heavily affected by overfishing and pollution.
The fact that sharks thrive in and around volcanoes shows that these two fearsome forces of nature share a very powerful connection!
I HIGHLY RECOMMEND THIS DOCUMENTARY!