A huge shark was found dead with a long 11-inch "blade" stuck in its back at a beach, leading scientists to investigate how the apex predator may have been killed.
Video taken earlier this year by citizen scientists captures the dead female thresher shark lying ashore on a beach at the town of Brega in Libya.
They point out the wound, which is on the lifeless shark's back, before pulling out a rostrum – the blade – belonging to a swordfish and measuring 11.8 inches long
It is said that the shark died from a penetrating wound with the "blade" puncturing the beast's heart from its back.
The thresher shark was just a little over 14 feet long when the citizen science initiative "Marine biology in Libya" arrived at the scene.
Experts suggested the swordfish measured about six feet long and attacked the shark from behind three days before it washed ashore.
Published in a journal Ichthyological Research, the scientists stated the rostrum belonged to the swordfish Xiphias gladius, "which is a highly mobile, predatory fish known to attack sharks, whales, humans and even boats".
The study also revealed how the shark died from the gruesome attack.
It reads: "The rostrum penetrated the shark in an acute angle of approximately 70 degrees to the anterior-posterior axis, directed towards the branchial apparatus, revealing that the swordfish must have been positioned dorsally from the shark and pierced it from behind."
And because of the position of the blade, the scientists believe the shark's injury resulted in nerve and artery damage along with its gill arches.
The study details: "This colouration was faded by the date of the second inspection three days later.
"The location of the injury, timing of wound infliction and lack of other apparent injuries lead us to the conclusion that the impalement was fatal and the ultimate cause of death for the thresher shark."
The team also notes that the attack may have been accidental and it was likely that two swordfish may have been feeding on the same prey or the swordfish was trying to scare the shark away from the meal.