Hammerhead Worms Are Toxic and Invasive, But Are They Dangerous?

Every now and then, we get word that a new killer invertebrate is invading our country — killer bees, murder hornets, fire ants, and the list goes on. Now there’s the hammerhead flatworm — the slimy, leech-like creatures with anvil-shaped heads. While they’re toxic and aggressive, hammerhead worms aren’t something to get too upset about. In fact, they’ve been common residents of American gardens since the early 1900s. Hammerhead worms are carnivorous and often cannibalistic. They’re sensitive to light and are active mostly at night, feeding on a variety of small, soft-bodied animals like snails, slugs and earthworms. They wrap around their prey with sticky mucus and use a mouth located on their belly to consume them. They use special enzymes to digest the prey outside of their body. After the digestive juices have done their job, effectively turning the prey into a puddle of goo, the hammerhead worm sucks its victim in with the help of a bunch of tiny hair-like structures on its underside. Fortunately, their danger is over-exaggerated. Hammerhead worms do pose a threat to earthworm populations, but they’re not dangerous to humans unless eaten. That’s because they contain the same poison that makes puffer fish so deadly. In other words, as long as you don't eat them, you're in no danger.