Alien Worms Have Invaded Tennessee: Unmasking the Hammerhead Worm Invasion

Imagine a new horror movie.............. cue horror soundtrack!

The alien surrounds its prey ... deploys a gooey tetrodotoxin which is 1,000 times more poisonous than cyanide.  The prey is killed.

The alien slowly devours its prey.

Alien hunters are out -- but they realize they must be careful.  

Cutting the alien in half just creates another full alien. 

 In fact, that's how it multiplies and has babies -- it just drops off its tail, which grows a new head.

Movie ends ..... real life begins

The hammerhead worm, known scientifically as Bipalium, is a creature straight out of a science fiction movie.

Hammerhead Worm -- grows up to 12 " long

These alien-like worms, with their distinctive hammer-shaped heads are in Tennessee.  Originally from Southeast Asia, these worms have hitched rides on potted plants and soil, spreading across the globe.  They likely arrived in the USA in the late 1800's.  

Head section of a hammerhead worm

Hammerhead worms are not just invasive; they are also toxic. They are one of the few terrestrial invertebrates known to produce the neurotoxin tetrodotoxin, a potent poison also found in pufferfish and the blue-ringed octopus. While they pose no direct threat to humans (nothing we've read says that they are a threat - but use your own diligence to decide), they use this toxin to immobilize their prey and deter predators.   

They Are Carnivores 

Hammerhead worms are carnivorous, preying on earthworms, slugs, insect larvae, and even each other. They detect their prey using chemoreceptors located under their head or ventral groove. Once they have immobilized their prey with their toxic secretions, they extend their pharynx from their body, secrete digestive enzymes, and suck the liquefied tissue into their branched gut.   

Given earthworms are extremely good for soil and the environment this could potentially lead to a problem in the future as the Hammerhead Worm population grows.

Hammerhead worm overtaking ground worm for consumption

They Self Reproduce

Hammerhead worms are hermaphrodites, possessing both testes and ovaries. They can reproduce sexually by exchanging gametes with another worm. However, asexual reproduction is much more common. They can leave behind a tail tip that develops into an adult, and if cut into pieces, each section can regenerate into a fully-developed organism within a few weeks.

The worms can reach up to a foot in length. They are earth-colored, found in shades of gray, brown, gold, and green. They prefer humid, warm habitats and are usually active at night, residing under rocks, logs, or shrubs during the day.

Despite their alien-like characteristics and invasive nature, there is no need for alarm. The Tennessee State University (TSU) Extension Coffee County has provided guidelines on how to handle these creatures if encountered. It is important to remember that these worms can regenerate if cut in half, so physical destruction is not recommended.

Disposing of Hammerhead Worms 

According to the UT extension ... 

1. Use gloves or tweezers to pick up the worm to avoid direct contact.
   
   
2. Place the worm in a zip-top bag with rubbing alcohol or place it in the freezer. Once the worm is dead, dispose of it in the trash.
   
   
3. Do not attempt to cut the worm in half as it can regenerate from each piece.
   
   
4. Avoid using salt to manage them in your garden as it may also harm earthworms.

Contacting Authorities After Finding a Hammerhead Worm

If you encounter a hammerhead worm, it is beneficial to document the sighting. Amy Willis Prince, the Coffee County Ag Agent, encourages residents to take an in-focus picture of the worm and email it to her at awillis2@utk.edu. Please include the location where the worm was observed.

The presence of hammerhead worms in Tennessee is a reminder of the delicate balance of our ecosystems and the potential impact of invasive species. While these worms are not harmful to humans, their impact on beneficial earthworm populations can have far-reaching effects on soil health and plant growth. By following the recommended procedures for disposal and reporting sightings, residents can play a crucial role in managing the spread of this invasive species.