Toxic hammerhead worm spotted in St. Thomas garden

Jessica Fugard was enjoying a lazy day in her backyard garden in St. Thomas, Ont., when she noticed something out of the ordinary. 

It was a flat, slimy worm, with a crescent-shaped head, that appeared to be eating part of a snail.

"I started poking it with my nail and thought, 'This looks interesting,' so I took a picture of it, and Googled it," said Fugard.

"After that, I was like, 'OK, let's not touch that.'"

As it turns out, the strange-looking invertebrate was a hammerhead worm, known in scientific communities as a bipalium — a predatory, toxic flatworm that's invasive to North America.

"I was really excited, actually. I've always been fascinated by bugs and worms. I was already joking with my brother that I might get my five minutes of fame over a worm — like all my collecting of bugs and worms and stuff as a kid finally paid off," Fugard said.

When Fugard posted a two-second video of the worm wriggling on a brick on a local gardening Facebook group, it amassed almost 1,000 shares and dozens of comments from locals, some urging her to report the finding to conservation officials.

That's exactly what she did, she said, adding she sent photos and information to invasive species specialists.

"I don't know what they're going to do moving forward, because I really don't want my garden ripped up," Fugard said.

"But, such is life."

From the Invasive Species Centre's perspective, it's always good to report what you see, even if the report ends up being inaccurate or common.

"We always encourage anyone who comes across an invasive species to report, and that protocol depends on the risk assessment of that species," said Emily Posteraro, a program development co-ordinator at the centre.

"If it's something common like garlic mustard, it's good to know where it is, but if it's something higher on the list like the Asian long-horned beetle, we're on alert."

Posteraro also encouraged people who see invasive species to send photos and other details along with reports, especially when potentially dangerous or damaging species are seen. She added she didn't have information pertaining to how serious of a threat hammerhead worms are.

"It never hurts to report it," she said.

Toxic, dangerous to children

Université de Montréal entomologist Étienne Normandin said the worms, which have been reported elsewhere in Ontario and Québec, are a definite concern in his eyes. 

They produce tetrodotoxin — the same toxin produced by pufferfish, which are notorious for killing people who eat them if not prepared correctly.

"It's a neurotoxin that gets to the brain pretty fast and it can hurt you. Of course, the toxin quantity is very small in the hammerhead worm," Normandin said.

"But, think of a situation where you have a baby, for example, or a kid that puts soil in their mouth and ingests it. Now, we have a problem."

If children — or animals — with a low enough body weight consume the worms, the danger is real, he said.

There's also an ecological danger, Normandin said.

"Hammerhead worms don't have predators, pathogens or parasites. Their population can grow fast," he said, adding they often crop up in new locales because of plants and soil being moved from one place to another.

Hammerhead worms, as predators, kill local native worms, slugs, leeches and other creatures, and have a negative effect on soil quality, he said. The only redeeming factor is they move slowly on their own, so their impacts are typically localized.

For people who may come across the worms in the wild, Normandin's suggestions align with Posteraro's.

"Record, record, record," he said, pointing to an online platform called iNaturalist.

"It's a well-known platform and scientists use it a lot. Recording new observations is crucial."

As of April 16, the website had verified hammerhead worm sightings in Ontario from Hamilton, Newmarket and Woolwich.

"On top of that, if you find one, they can die pretty fast from salt, or putting them in alcohol or bleach."

That's advice Fugard didn't have when she found the worm on her property.

"I burnt it. I had my lighter there, so I burnt both ends," she said.

Regardless of the outcome, Fugard said, she plans to spend a few evenings in the garden looking for more to ensure the situation is dealt with.