Micro-season: “The Earthworms Rise”

We have entered the micro-season of “The Earthworms Rise”, which is the second micro-season of the mini-season of First Summer.

Each mini-season contains three micro-seasons. The micro-seasons within First Summer are:

• The First Frog Calls (May 05 – May 09)
• The Earthworms Rise (May 10 – May 14)
• Bamboo Shoots Appear (May 15 – May 20)

These seasons were established in 1685 by Japanese astronomer Shibuka Shunkai and are specific to Japan. However, just because the calendar focuses on Japan doesn’t mean it isn’t applicable to others.  No matter where you live you can use these seasons as a starting point for your personal exploration of the world around you. 

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Earthworms

The term “earthworm” refers to a fairly large group of invertebrate animals that have a segmented tube-like body. Earthworms fall into the taxonomic subclass known as Oligochaeta, which is part of the phylum Annelida. Animals that are part of the phylum Annelida include earthworms, ragworms, and leeches.⁽¹⁾  

Trying to follow the chain of taxonomic classification for the earthworm is actually quite confusing once we start heading into the order, suborder, family, and genus level.

Taxonomy of Earthworms

I find graphics like the one below helpful when trying to remember the flow of the taxonomic system. The “Domain” classification is the broadest and most general classification, whereas the “Species” classification is the most specific.

Keep this graphic in mind as we move from the order of Opisthopora to the species of Lumbricus terrestris

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Opisthopora is the order of animals that includes most terrestrial worms.⁽²⁾ The suborders of Lumbricina and Moniligastrida contain 23 families and over 6,000 different species of animals that can be called earthworms.⁽³⁾ 

The earthworms that are common in North America, Europe, the Middle East, Central Asia, and Japan fall under the Lumbricidae family.  There are then 44 genera listed under this family.⁽⁴⁾ 

The genus Lubricus contains the species Lumbricus terrestris, or common earthworm. Lumbricus terrestris is native to Europe but also found throughout North America and western Asia.  Interestingly, the range map for the Lumbricus terrestris does not include Japan.⁽⁵⁾

Some known earthworms found in Japan that fall under the Lumbricidae family include Aporrectodea trapezoides and Eisenia japonica.⁽⁶⁾ Other earthworms found in Japan, but not in the Lumbricidae family include Amynthas corticis and Amynthas micronarius. Both of these earthworms are in the Megascolecidae family.⁽⁶⁾ There are 79 genera listed in this family of earthworms.⁽⁷⁾

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Earthworms and Ecosystem

In 1881, Charles Darwin wrote The Formation of Vegetable Mould Through the Action of Worms. In this book, he states, “It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.”⁽⁹⁾ The “lowly organised creatures” that Darwin is talking about are of course earthworms!

Earthworms contribute to the health of our ecosystem in a few ways.

1. Earthworms are able to recycle organic material into usable nutrients. Earthworms consume plant matter and then transform it back into nutrients like nitrogen and phosphorus that can be used for other plants.^(5,9)
2. Earthworms improve soil structure. Earthworms travel through the soil by burrowing. As they are burrowing, they are consuming plant matter and creating small “pores”⁽⁹⁾ within the soil.  These pores improve soil aeration and water infiltration, which then allows nutrients to reach plant roots.^(5,9)
3. Food for Predators.  Earthworms provide a food source for many animals including birds, rats, toads, and some snails.^(5,9)  

It is quite amazing when you think about the impact that these little underground creatures have on the earth’s living systems. Just by burrowing and eating, they can transform the soil into fertile ground that can support the growth of new life and become the foundation for a healthier ecosystem.

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Poems about Earthworms

Carl Dennis published “Worms” in the May 2003 issue of Poetry Magazine.  In this poem, Dennis talks about the debt that we owe to our silent animal partners.

Aren't you glad at least that the earthworms
Under the grass are ignorant, as they eat the earth,
Of the good they confer on us, that their silence
Isn't a silent reproof for our bad manners,
Our never casting earthward a crumb of thanks
For their keeping the soil from packing so tight
That no root, however determined, could pierce it?

He then continues by wondering what would happen if the earthworms asked for some acknowledgment.

Imagine if they suspected how much we owe them,
How the weight of our debt would crush us
Even if they enjoyed keeping the grass alive,
The garden flowers and vegetables, the clover,
And wanted nothing that we could give them,
Not even the merest nod of acknowledgment.
A debt to angels would be easy in comparison,
Bright, weightless creatures of cloud, who serve
An even brighter and lighter master.

Dennis uses these verses as a setup to talk about paying gratitude to a selfless friend. You can read the complete poem and learn more about Carl Dennis by visiting PoetryFoundation.org

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Haiku about Worms

My search for haiku about earthworms was not that successful.  In fact, even the haiku that I found that mentions earthworms, is not about earthworms. 

the old dog
looks as if he's listening...
earthworms sing
-Issa

David G. Lanoue explains that according to Kiyose, a Japanese book of seasonal words: “On autumn evenings, when one says one is hearing the ‘jii-jii’ song of earthworms, in fact they are referring to mole-crickets”⁽¹⁰⁾

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Yosa Buson offers us another haiku about worms. But again, not earthworms.

Worm eaten — 
the sweet lower leaves
 of tobacco
-Buson

The worm that Buson may be referring to in this haiku is the hornworm.  The hornworm is known for eating tobacco leaves. This worm is actually a caterpillar and transforms into the tobacco hawk moth.⁽¹¹⁾

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Finally, we have a haiku by Matsuo Basho

In the moonlight a worm
silently
drills through a chestnut
-Basho 

This is a fairly well-known haiku by Basho. In this poem, Basho may be referencing the chestnut weevil. The larvae of the chestnut weevil “are white, legless grubs that can devour the entire contents of a nut.”⁽¹²⁾ With that said, I believe that Basho may also be using the worm and the chestnut as a metaphor for something related to the human condition. What do you think? Do you think that Basho is talking about more than the chestnut and the worm?

Feel free to share your interpretation of Basho’s “In the moonlight a worm” haiku in the comments below.

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Resources:

1. “Annelida”; Wikipedia
2. “Opisthopora”; Wikipedia
3. “Earthworm”; Wikipedia
4. “Lumbricidae”; Wikipedia
5. “Earthworm”; National Geographic Kids
6. Keiko Kishimoto-Yamada and Yukio Minamiya; “Earthworm species and density in semi-natural grasslands on rice paddy levees in Japanese satoyama”; Biodiversity Journal
7. Darwin quoted in “The Importance of Earthworms: Darwin’s Last Manuscript” by Jeremy Megraw: New York Public Library
8. “Megascolecidae”; Wikipedia
9. “Earthworms’ role in the ecosystem”; Science Learning Hub
10. Carl Dennis; “Worms”: Poetry Foundation
11. Kobayashi Issa; “the old dog”. Retrieved from Haiku of Kobayashi Issa by David G Lanoue 
12. “Manduca sexta”: WikipediaBruce Bordelon; “Chestnut Weevil”: Purdue University

Want to support our work? Visit the Naturalist Weekly bookstore and browse our curated lists of books of poetry and haiku. Or pick up a gift card that can be used throughout the store.   

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