Hammerhead Worms

Last year I found a strange flat hammerhead worm in my friend’s yard. It was like nothing I’d seen before. I was compelled to investigate and what it was. This is what I found out.

This species is a “hammerhead worm” and is usually only seen during very high humidity situations, such as a lot of rain. They are usually found in cool, dark, moist areas. It favors a moist habitat and is usually found near outdoor water faucets, or where the soil remains wet. They are carnivores and can be cannibalistic. They usually move and feed at night. They have been found commonly in American greenhouses since 1901. The species was discovered in 1878 in the greenhouses of Kew Gardens near
London, hence its scientific name.

They belong to a very primitive class of animals. This land planarian is flat, slender and brown, with longitudinal stripes; it can be large, up to 10 inches in length. The head is shovel-shaped (wider than body) and there are numerous minute eyes along its edge.

There are four different species of these Bipalium flatworm currently found in the US. Three eat only earthworms; one eats snails and slugs. Bipalium kewense is found across the southern states and may get over 10 inches. It has five dark stripes along the back including a thin middle stripe. Bipalium adventitium is found across the northern states, reaching about 4 inches. It has one narrow dark stripe on the back. Bipalium vagum is the mollusk eater now found in the southeastern US. It has three thick dark stripes, a dark neck collar, and two dark head spots.

Their bodies are very easily damaged. The flat worms will reproduce by division if cut or broken. Reproduction is principally by fragmentation at the posterior end. Lateral margins pinch in about 1 cm from the tail tip. Severance occurs when the posterior fragment adheres to the substrate and the parent worm pulls away. The posterior fragment is motile immediately, and within seven to 10 days a lightly pigmented head begins to form.

They have been reported to be a pest in earthworm beds. There are no known forms of pest management. They are not known for spreading diseases.

-Maureen Clark

 

Comments

[Anthony Truter]

I have discovered that the only quick method to kill the hammerhead worms is to spray them with metholated spirits. Make sure you spray the entire length of the worm.

[Debby Martin]

Ren, this is your worm, called a flathead, or hammerhead worm