Grad Student Finds Rare Worm

 
February 10, 2006

By Jessica Mullins – University of Idaho Argonaut   

It was confirmed on Jan. 30. The earthworm sample graduate student Yaniria Sanchez-de Leon collected was what she expected it to be: the rare giant Palouse earthworm, not seen in about 20 years.

Sanchez-de Leon, a soil science doctoral candidate, went to Washington State University’s Smoot Hill Ecological Preserve with two University of Idaho environmental science students for common earthworm sampling last spring. They dug square-foot-sized holes. When Sanchez de-Leon put her shovel in the soil to gather the last soil sample she recognized a piece of a smooth, white earthworm in the shovel.

“When I first saw it I was sad that I had cut it,” she said.

She gathered the rest of the worm with one more shovel scoop.

“I felt really excited because it was different from all the other earthworms I got there,” she said.

The length of the worm is about six inches. It can reportedly grow up to three feet long.

“Not much is known about the species at all,” said Jodi Johnson-Maynard, UI assistant professor of soil and water management.

Little is known about the worm’s burrowing habits and how widely distributed it is across the Palouse, Johnson-Maynard said. It has been found only in the Palouse, though it has relatives from Australia that can reach 10 feet.

James “Ding” Johnson, UI Plant, Soil and Entomological Sciences Department head, was one of the last scientists to document a sighting of the worm. The worm is a “biological mystery,” he said.

At a forest clearing at the edge of Moscow Mountain, Johnson and a graduate student rolled back a piece of moss in search of beetles. They uncovered several cream-colored worms.

“There was surprise and excitement,” Johnson said.

They collected two worms as the others quickly slid away. One of the odd things the worms did was spit, possibly as a defense mechanism, several times as they were handled, Johnson said.

“That was one of the moments that were unexpected,” Johnson said. “It was fun.”

They were smooth and about 12 inches long, he said. They are recorded as being lily-scented, but Johnson didn’t recall the scent.

“It was supposed to be the first time specimens were collected and preserved in we don’t know how many years,” Johnson said.

The specimen Johnson and Sanchez-de Leon found was sent to the same entomologist in Oregon, who confirmed it was the rare giant Palouse earthworm, “Driloleirus Americanus.”

When she heard of the confirmation, “I was really, really, really happy,” Sanchez-de Leon said.

The worm is considered to be rare and difficult to find. The first recorded description of the worm was in the late 1800s. There is a report from 1978, but no one has seen the specimen, making it difficult to trace.

“They dig very deep in the soil,” Sanchez-de Leon said.

It is hard to study giant earthworms because they sense vibrations and move quickly, Johnson-Maynard said.

The destruction of its habitat could be the main reason the native earthworm is rare. Johnson said about less than one percent of the Palouse remains in its natural form.

The worms may also suffer from competition of European-introduced earthworms, such as the worms that appear on the cement in the rain.

Earthworms have positive effects on soil and plant growth. They are an important species, Johnson-Maynard said.

In the spring, Sanchez-de Leon and Johnson-Maynard will search for the giant Palouse worm. A new electrical current system sampling technique will use electrical currents to bring the worms to the surface.

Sanchez-de Leon said she wants to encourage others to not look for the worm on their own. They are easy to harm and someone could easily destroy their habitat, she said.

Sanchez-de Leon, from Puerto Rico, earned her bachelor’s degree and master’s degree from the University of Puerto Rico. She received a fellowship from the national science foundation to attend UI. After she graduates next spring, she plans to look for a job in a higher academic institution or university in the United States or Puerto Rico.

The specimen she found will be kept in the entomology museum in UI’s Agricultural Science Building.