Scientists know that most shark species give birth to live young, but the conditions under which many species deliver their young has remained a mystery. Where and when do shark births happen in the wild?

Shark births are so elusive that there are no known photographs ever taken of any oceanic shark species giving birth in the wild. The vastness of the ocean, and the shyness of many shark species, has made shark birth one of nature's great secrets. That is, until now.

The remarkable image shown above portrays what has never been caught on film before: a baby thresher shark coming into the world. The image was taken during a research dive in 2013, now published in the journal Coral Reefs, reports the BBC

"We were doing a standard survey - out every day, making observations," said Dr. Simon Oliver from the University of Chester. "One of [our team] is a photographer - Attila Kaszo. He took the picture of the shark, and when he processed the image and showed it to me, I freaked out."

Oliver, who also said that seeing the image was one of the most exciting moments in his career, was not the only researcher floored by the photograph.

"I have never seen a comparable image for any other pelagic shark," said Dr. Simon Thorrold, a senior scientist from Woods Hole Oceanographic Institution in Massachusetts, to BBC News. "It may well be, or at least the first time that the event has been photographed, but this is always difficult to say definitively."

The picture is not only significant for being the first ever taken of its kind, but it also helps to answer some long-held questions about the species. For instance, although pregnant thresher sharks are known to frequent the seamount where the image was taken, scientists were previously unable to confirm if the area also served as their pupping ground. 

Researchers are also hopeful that the finding could help establish this pupping region as a marine protected area, a conservation win for a species that is highly vulnerable to overfishing. 

Thresher sharks are most recognizable for their extremely long tail fins, which they use as a weapon to stun prey. Unfortunately, their impressive tails also make them a prized ingredient for shark-fin soup, a delicacy in Chinese cuisine. The popularity of the dish has raised concerns over the sustainability of shark fishing.

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