(ORDO NEWS) — Several shark species, including reef sharks ( Triaenodon obesus ) and bronze hammerhead sharks ( Sphyrna lewini ), are very common around the most active underwater volcanoes, including in their vents. Why they choose such places remains one of the main mysteries of science related to the ocean.
“In fact, it is still not known why they live there. It might have something to do with reproduction, or it might just be looking for food.” Michael Heithhouse, marine ecologist at Florida International University.
A documentary about sharks, released by National Geographic in 2015, tells about the discovery. Filming took place near the Kawachi volcano near the Solomon Islands. But further research into the strange behavior of sharks has been interrupted by Kawachi activity. Therefore, questions remain about how sharks survive in an active crater 18 meters below the surface, where temperatures are approaching boiling point.
Heithhouse considers that the answer may lie in the ampullae of Lorenzini, the sense organ of several orders of fish, which allows them to pick up electric fields and notice extremely small changes in their strength.
According to the scientist, sharks can sense changes in the Earth’s magnetic field. This could potentially allow them to sense an impending eruption and move to safety. This mysterious sixth sense probably gives sharks the opportunity to hunt and search for other volcanic islands.
The exploration brought Heithhouse to Reunion Island, home to the active volcano Piton de la Fournaise. Sharks are so numerous here that swimming in coastal waters has been prohibited in recent years. Since 2011, 11 people have died in Reunion as a result of shark attacks. Blunt sharks ( Carcharhinus leucas ) were mainly responsible for the tragedies.
Heithhouse is confident that sharks prefer areas near active volcanoes for two reasons. Firstly, the sediment washed off the slopes of the volcanoes makes the water cloudy, and this is the ideal conditions for hunting top predators. In addition, extreme habitats can provide a refuge for sharks from humans and other largest sharks.
“The biggest threat to sharks is overfishing. Too many of them are caught, and this is due to the demand for their fins and meat. However, you are unlikely to consider fishing near an active volcano, and the largest sharks are likely to be less inclined to enter.” Michael Heighthouse.
“We may not know exactly why they live there, but the fact that they have been observed in large numbers near volcanoes in a fairly short period of time suggests that this is an important place for sharks. If it wasn’t the best place to live, they wouldn’t be there, ”concludes Heithhouse.
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