The centipede-like creatures, around 15 to 30 centimeters (6-12 inches) long, devour everything from coral to the dying or dead catch in fishing nets—and rising sea temperatures caused by climate change are drastically boosting their numbers.

Barone pulls a long, wriggling red worm off a headless mackerel in his boat. Its venomous white bristles come off at the slightest touch and the 34-year-old says he has been stung several times, once even in the eye.

The fish are attacked as soon as they get caught in the net.

"They eat the head, the whole body, they gut it," Barone said as he pulled up a mangled sea bream while fishing off the village of Marzamemi, on the southeastern tip of Sicily.

Fireworms are native to the Mediterranean but used to be fewer in number and spotted only off Sicily in summer.

"With global warming the waters are heating up and becoming an ideal habitat for them, and they are growing in number, year on year... the whole year round," said Barone, who has fished since boyhood.

Gnawed fish cannot be sold, so fishermen reduce the time the nets are down in a bid to stop a feeding frenzy—resulting in a smaller catch, bits of which come adorned anyway with brown, green or red fireworms.