Grisly Beach Discovery Reveals Broken 'Sword' That Slayed an Unlucky Shark

 When a dead Alopius vulpinus washed up onshore, it had been obvious what had killed it - a swordfish had stabbed it from behind and left an oversized hunk of its "sword" embedded within the beast, a brand new study finds.

No one saw the particular attack, so it's unclear why the swordfish jabbed the shark. But the 2 ocean predators may are competing for prey, the researchers said.

"The possible scenario is that both species were hunting on a faculty of fish or on squids within the deep," said study lead researcher Patrick Jambura, a doctoral student within the Department of Paleontology at the University of Vienna. 

(The Ichthyological Society of Japan 2020)

It's also possible the 2 ocean predators were fighting over territory, or that the swordfish accidentally stabbed the thrasher and left nearly 12 inches (30.1 centimeters) of its "sword" within the victim, he said.

News of the fight's deadly aftermath spread when the shark's body washed abreast of the Mediterranean coast of Libya, near the town of Brega in April 2020. an area citizen scientist group learned about photos and video taken of the 14.5-foot-long (4.5 meters) dead shark.

After seeing the evidence, Jambura told Live Science "I was just stunned for some moments".

Swordfish (Xiphias gladius) are known to defend themselves against blue sharks (Prionace glauca) and mako sharks (Isurus oxyrinchus), as these sharks take advantage of swordfish. 

Swordfish have also been reported attacking whales, sea turtles, inanimate objects, including boats and submarines, and even humans, Jambura and his colleagues wrote within the study.

In 2015, "a diver was killed in Hawaii when he speared a tiny low swordfish that had wandered into a marina," said Yannis Papastamatiou, a marine biologist at Florida International University, who wasn't involved in the study. "It speared him through the chest."

But thresher sharks (Alopias superciliosus) eat small fish "and wouldn't be a threat" to swordfish, Jambura said.

Whatever the reason for the stabbing, "we know that the swordfish attacked from above - the shark was presumably not even alert to the danger [it] was in until it absolutely was too late," Jambura said.

(The Ichthyological Society of Japan 2020)

It appears that the roughly 10-foot-long (3.1 m) swordfish stabbed the shark just behind the top, leaving a cut 2 inches (5 centimeters) deep and three inches (8 cm) wide where it pierced the shark's gill system.

Because nobody performed a necropsy (an animal autopsy), there aren't any thanks to knowing whether that caused deep internal damage, "but from the angle and therefore the depth of penetration, it's safe to mention that the gill region was heavily damaged, possibly also some important arteries," Jambura said.

While this is often the primary reported case of a swordfish killing an Alopius vulpinus, scientists do not know how often this happens within the water's depths.

"We rarely see evidence of those outcomes: Sharks are negatively buoyant and can sink after they die," Papastamatiou told Live Science in an email. "Unless they destroy on the beach like here (which is rare, most will sink into the deep sea), then we can't find evidence of the interaction."

The swordfish left the altercation physically damaged, but that does not mean the fish died; there are known cases of billfish (a close relative of the swordfish) that have damaged, malformed, or maybe missing rostra (or its pointy "sword") that "were apparently still in good physical shape," the researchers wrote within the study. Perhaps the assailant survived.