JoAnne Skelly
Worms are one of nature’s mind-boggling creatures. There are around 2,700 different kinds of earthworms worldwide. There can be more than a million earthworms in one acre of land and according to Illinois University Extension, “the largest earthworm ever found was in South Africa and measured 22 feet from its nose to the tip of its tail” and “The Australian Gippsland Earthworm grows to 12 feet long and can weigh 1.5 pounds” (IUE). Can you imagine finding one of these in your yard?
For more, go to https://web.extension.illinois.edu/worms/facts/
Worms have both female and male reproductive organs (hermaphrodites). They mate by joining a swollen area near their heads called a clitella. Sperm is exchanged during this process. Then, each worm forms eggs. Baby worms hatch from cocoons. To survive and thrive, worms need food — eating huge amounts of topsoil each year — as well as moisture, oxygen, and a favorable temperature. They can eat their body weight every day.
Obviously, worms have no legs, but did you know they don’t have eyes either? And yet they can sense light, primarily from their front (anterior) end. They “become paralyzed if exposed to light for too long (approximately one hour)” (IUE). Worms have the amazing ability to replace lost body segments, except for the head in rare instances. This extent of segment replication varies with the species of worm.
These cold-blooded invertebrates are important for agriculture and soil productivity. They are renowned for their tunneling, which aerates the soil, improves porosity and water infiltration. Tunneling also brings up subsoil as they go, mixing it with topsoil. Worms provide nitrogen, phosphorus, potassium and calcium to plants as they move through the soil oozing slime and excreting worm castings. Micronutrients, such as zinc and boron, are highly available in the casts as well. I have often written of the benefits of soil microbes and earthworms excrete high concentrations of these beneficial critters. Additionally, their slime is good for holding soil particles together, which improves soil structure. Besides soil improvement, the slime protects the worm’s skin from drying out, which can kill it.
Worms were a favorite research topic for Charles Darwin, who, according to IUE, spent 39 years studying them. For excellent information on worms see Penn State University Extension’s publication “Earthworms” at https://extension.psu.edu/earthworms.
JoAnne Skelly is Associate Professor & Extension Educator Emerita University of Nevada Cooperative Extension. Reach her at skellyj@unr.edu
