HomeOutdoorsNewsInvasive hammerhead flatworms are on the rise in Texas

Invasive hammerhead flatworms are on the rise in Texas

by Caitlin Berard
Hammerhead flatworm, an invasive species in Texas
(Photo by Gunter Fischer/Education Images/Universal Images Group via Getty Images)

In the United States, we’re no strangers to invasive species. From Asian giant hornets (better known as murder hornets) to Burmese pythons to feral swine, we have more than enough harmful species to contend with. Among the “nastiest,” however, is the hammerhead flatworm.

Though maybe not the most scientific way to put it, points were made when Texas resident Jessica Pittman made her Facebook post warning others about the toxic trespassers.

“This is a hammerhead worm. One of the nastiest invasive species in our state,” she wrote. “If you see one, do not touch it with your bare hands. They are poisonous!!!!! They are extremely damaging to our native ecosystem.”

So, yes – hammerhead flatworms are, in fact, poisonous. They produce tetrodotoxin, the same poison that makes pufferfish deadly.

Unlike pufferfish, however, they produce such a small amount that you would have to eat a lot of worms to produce the same fatal effect (and who wants to eat a worm?).

That said, it is a good idea to avoid touching them with bare hands, as the neurotoxin they secrete can be a skin irritant. Should you touch one, wash your hands with hot soapy water afterward and you’re fine.

It’s more important to keep pets away from them. Should a dog eat one, for example, it could cause vomiting and illness for several days, requiring immediate veterinary care.

Hammerhead flatworms pose a threat to native earthworms

While strange, slimy, and snake-like at a foot in length, hammerhead flatworms aren’t a real threat to humans and only a mild one to pets. The true threat they pose is to earthworms, their preferred meal.

Earthworms aren’t a species we think about all that often, but they’re essential to a healthy soil ecosystem. Through their activity in soil, earthworms increase nutrient availability, improve drainage, and create a more stable soil structure.

In other words, they help “turn” the soil. Without earthworms, we would experience a drastic decline in soil quality.

Because of their harmful, invasive nature, researchers recommend destroying hammerhead flatworms when spotting them. But there’s a catch.

Like other planaria, hammerhead flatworms reproduce through a process called binary fission. This means cutting one in half will only cause more worms. The portions that are cut will begin to regenerate a new flatworm in about 10 days.

So while they aren’t “literally immortal,” as Pittman put it, they kind of are. To effectively dispose of a hammerhead flatworm, use gloved hands, a paper towel, or a stick to pick it up and place it in a sealable plastic bag with salt. Seal the bag so the flatworm can’t crawl out and throw it away.

This goes for hammerhead flatworms found anywhere in the US, not just in Texas. While they’re currently causing a stir in the Lone Star State, the invasive species can be found anywhere that provides the hot, humid environment in which they thrive.