Featured Creature: Oregon Giant Earthworm

Photo Credit: Chris Baugher CC BY 2.0 via Wikimedia Commons

What creature smells like lilies, is particular about the type of soil it resides in, and is the largest of its kind in North America?

The Oregon Giant Earthworm!

A Similar Species: The Giant Palouse Earthworm (Driloleirus americanus)
Photo Credit: Chris Baugher CC BY 2.0 via Wikimedia Commons

A fews days after moving into college this past August, I took a long walk in search of solitude and refuge from the chaos of move-in week. I found myself in the garden behind my favorite building, the science center. In need of grounding, I placed my hands on the sun-warmed soil, soaking up the pull of gravity. After a while, I began playing with the soil, then digging small depressions to see what lay beneath the surface. Almost immediately, a beautifully plump earthworm popped up. I picked it up in my hands and watched its slow and strategic wriggling movement across my palm. Not wanting to take up too much of this fascinating creature’s time, I placed it back on the ground. As it burrowed back into the soil, the organic matter above it moved up and down, almost as if the ground was breathing and the earthworm was its lungs. 

After my interaction with the earthworm in the science center garden, I began to notice that earthworms appeared just about everywhere on campus, particularly outside my apartment. Perhaps it was due to my intimate interaction with that one earthworm, or perhaps it was due to the immense amounts of rain that we received over the past few months. Either way, earthworms had quietly invaded the campus in surprising numbers. 

This isn’t the first time earthworms have taken over an area. There are over 7,000 thousand species of earthworms across the world, both native and non-native. For example, earthworms are generally considered non-native in North America, having hitched an inter-continental ride with other mobile organisms (such as humans with boats). 

Some people love them and some people squirm at the sight of them, but no matter how you feel about their appearance, there’s no denying that the earthworm is anything but ordinary. This creature looks so simple – long, brown, and snake-like – yet it has such a significant role to play within the ecosystem. This week, I’m very excited to share one particularly unique and fascinating earthworm species with you: the Oregon Giant Earthworm. 

A Delightfully Fragrant… Earthworm?

Earthworms are a fascinating example of biodiversity due to the vast array of sizes, shapes, colors, and climates that they represent. One of the largest earthworm species in North America is called the Oregon Giant Earthworm, or Driloleirus macelfreshi. This resident of the Pacific Northwest has been known to reach a length of 4.3 feet (1.32 meters) in length! 

The pale-white colored Oregon Giant Earthworm is perhaps one of the most pleasantly fragrant in the kingdom of crawlers. It emits saliva that smells like lilies! Have you ever been asked what kind of special power you would have if you were a superhero? Nevermind having superpowers like flying or becoming invisible… if I had the option, I’d choose to smell like a sweet flower just like our soil-dwelling friend. Even more interesting is that it is thought to emit such fragrant saliva as a chemical defense!

Location, Location, Location!

This sweet-smelling invertebrate likes to stick to its pad. The Oregon Giant Earthworm is native to the Pacific Northwest, specifically regions in Oregon such as the Willamette Valley and Lane County. It strongly prefers mixed woodland areas with a very specific soil type. 

“Middle Fork Willamette River, Oregon” by Bonnie Moreland, licensed under CC PDM 1.0

The soil should be well-drained and finely textured with plenty of clay content. The soil should be barely disturbed, and near a reachable water table. For a little something extra, the Oregon Giant Earthworm likes soil that leans on the acidic side, particularly because it has mainly been found in forests containing lots of conifers and abundant species such as the Douglas Fir, the Grand Fir, and the Bigleaf Maple.

However, even a creature of such habit as the Oregon Giant Earthworm likes to spice things up for special occasions, and will spend some time above ground among the grass to reproduce. 

Fun fact: did you know that all earthworms are hermaphrodites? This means that each individual has both male and female reproductive organs, but most earthworms still need to exchange sperm to fertilize eggs and successfully reproduce.  

A True Woodlander

In the human world, we often pride ourselves on the cultural foods that we eat based on the regions that we come from. Similarly, the Oregon Giant Earthworm eats staple foods from the very niche area that it resides in. This includes moss, wood, grass, seeds, stems, and decaying conifer needles. Essentially, our soil-burrowing friend enjoys eating the tasty treats that the flora of the ecosystem pass down to the ground for decomposition. The Giant Oregon Earthworm goes to work consuming these delicacies and, after processing them internally, deposits casts into the soil. These casts greatly improve soil health, and in addition to burrowed tunnels, are an extremely important contribution made by the earthworm to the overall health of the ecosystem.

Watch this video to learn more about how all earthworms make gigantic contributions to the soil, no matter the species:   

A Rare Gem

The Oregon Giant Earthworm is quite rare, hence why there aren’t any photos of them in this edition of Featured Creature. It has only been sighted about 15 times, with the last instance taking place 36 years ago in 1985. NatureServe lists the elongated earthworm as “critically imperiled,” which is sadly just one step away from extinction. As we all know, this earthworm lives a very specific lifestyle, and unfortunately agriculture and building development caused by humans has decreased the available habitat that is so perfect for the Oregon Giant Earthworm. 

Despite its critical conservation status, there is still hope for the Oregon Giant Earthworm! Scientists are still searching for live specimens of the species and conducting research to learn more about its history, habitat, and characteristics. It is still possible that more individuals from this species will be discovered, and with more knowledge about their life cycles, it is possible that their population could be restored as well. 

With blossoming love for our floral-scented friend!

By Abby Abrahamson