Would you love me if I was a worm?

This Valentine’s Day, don’t forget about the humble earthworm.

As our hearts warm up for Valentine’s Day, we are reminded spring is just around the corner — which means more earthworm sightings! Worms are known as the squishy, wriggly little guys that come out after a long rain and help loosen up the soil in our yard. But how much do we really know about them?

Aliens among us

First, let’s tackle (get it?) the slimy fact that most earthworms in the U.S. are invasive. That’s right — many of the common earthworms we see today were native to Europe and Asia, arriving centuries ago as global travel became more frequent. 

The silhouette of an earthworm can be seen against a blue glowing mucus.
A Diplocardia worm secretes its bioluminescent mucus. Credit: Milton J. Cormier

There are a few species of earthworm native to North America and the United States, like Diplocardia longa which can be found in sandy soils of southern Georgia. Many earthworm species share similar physical characteristics, life cycles, and behavior patterns. However, Diplocardia longa is one of several unique species with the ability to secrete glow-in-the-dark mucus to startle and distract predators. Pretty cool!

The birds and the bees (and the worms)

Earthworms are part of the small percentage of animals that exhibit hermaphroditism, meaning they have both male and female reproductive organs. Lucky for them — they can mate with any other individual of their own species. Earthworms aren’t choosy, but they are romantics: worms will mate every 7 to 10 days. They do this by laying next to each other in opposite directions so that the “head” of one is next to the tail of the other and exchanging sperm.

A little while later, each worm secretes a mucus ring containing their eggs and the sperm they received from their latest fling, which will become a cocoon that rests in the soil until new worms hatch to begin their life cycle all over again. A worm cocoon can contain anywhere between two and 20 new hatchlings, so one earthworm mating session can produce up to 40 young, wriggling worms!

Want a deeper dive into how worms find their “soil” mate?

A sweet and dirt-y treat

You’ve likely heard the phrase, “The early bird gets the worm”. Many birds, like the silly-looking American woodcock, love to feast on earthworms — worms in the Apporectodea and Diplocardia genera comprise up to 99% of a woodcock’s worm diet. Eastern moles also prey heavily on earthworms. Bait collectors take advantage of this predator-prey relationship by using a method called “worm grunting” to vibrate the ground in a way that mimics a digging mole and frighten unsuspecting worms from their soily homes. Studies suggest other predators like wood turtles and herring gulls have learned this same trick to hunt for juicy earthworms. Would you eat an earthworm?

If you’re squirming for more wildlife facts, you can learn more here, here, and here.

| , ,
Published: February 8, 2024