The discovery of a shark with a swordfish bill embedded in its heart sparked a new study into how the two marine predators could have become locked in mortal combat.
The dead thresher shark was found on the shore near Brega in Libya in April this year.
A broken-off swordfish bill was found lodged in its body, nudging on its heart.
Researchers determined the attacking fish measured about 280-310cm, meaning it was an adult.
Thresher sharks do not normally prey on swordfish, which have been known to fight other types of shark in self-defence.
The authors of the study, led by Patrick Jambura from the University of Vienna, decided that it was most likely the swordfish attacked the shark in a battle for resources – meaning if fish populations in the Mediterranean continue to shrink, such encounters could become more common.
Mr Jambura, a PhD student, told Forbes it was an "alarming signal".
"For one, it is another case that shows how aggressive swordfish are, but more importantly, we can exclude a defensive behaviour as the trigger for this attack," he said.
"It either happened in the heat of the moment, when both species were hunting on the same prey resource (schooling fish or squid) or it might have been even a direct attack to get rid of a competitor."
As for the swordfish – the species is able to repair damaged bills, but it will likely not regrow to the length it was.
Source: 9News https://www.9news.com.au/world/swordfish-kills-shark-new-research-explains-why/9826fc7a-3724-4369-9c3a-34e1f11db798