Frenzy of clamworms appear in South Carolina harbour

'You might not want to go swimming.'

A "frenzy" of marine worms with hooked jaws showed up at a harbour in Charleston, South Carolina earlier this month.

It's just a sign of the times: these 'clamworms' appear in the thousands in the area each spring. In a Facebook post, the state's department of natural resources said they're usually found on the seafloor but in the spring they kick into reproductive mode and morph into a form called 'epitokes.'

And when epitokes are in town, "you may not want to go swimming," the department says, on account of their hooked jaws.

“This fascinating phenomenon occurs every year at our marine headquarters in Charleston and is often followed by hungry throngs of fish and birds along the marsh edge,” they added.

Clamworms can reach up to 15 cm in length and they're a food source for bottom-feeding fish and crustaceans. If you've never seen one up close, have a look: they are straight-up otherworldly:

Nereis

Courtesy: Wikipedia.