Newly Discovered Earthworms: Freshwater Species of the Week

As any gardener or farmer should be able to tell you, earthworms can play an important role in ecosystems, by churning up soils, leaving copious amounts of nutrient-rich waste, and serving as food for a wide range of wildlife. Many young students dissect earthworms in biology 101, but there is still a lot we don’t know about this industrious group of Annelids (“everyone’s favorite” phylum according to UC Berkeley).

A study published this week in ZooKeys (an open-access, peer-reviewed journal of biodiversity) identified 10 new species of semi-aquatic, freshwater earthworms. The worms, all in the genus Glyphidrilus, inhabit the fringes of rivers, steams, ponds, and canals in Thailand. Each species seems to inhabit only a single water basin, which is another piece of motivation for protecting a wide array of habitat.

Glyphidrilus earthworms in Thailand, newly described species. Photo: Somsak Panha / 3.0 CC-By

The researchers suggest that Thailand’s monsoonal climate contributed to the proliferation of worm species, since the unevenly shifting weather may have helped drive micro-climate variation, which in turn led to greater adaption and specialization among the related worms.

The worms burrow u-shaped cavities into moist soil. Then they stick their posterior, square-tipped ends out, above the surface. They also have “wings,” flaps of extra skin near the tip. Scientists aren’t sure what the wings are for, but theories include aids in copulation and larger surfaces for oxygen exchange.freshwater species of the week

These Glyphidrilus worms often make their homes in Thai rice paddies, where they help improve farmers’ yield by aerating the soil and depositing nutrients (aka poop). (See “Talking Poop With Author of ‘The Origin of Feces.'”)

Study author Somsak Panha from Bangkok’s Chulalongkorn University said in a statement, “The worms will survive in areas using chemical fertilizers but not those using chemical pesticides. However, the worms did well in areas of organic farming and so are likely to be sensitive to modern agrochemical contamination of the environment. They may play an important role in organic rice farming.”

News of these 10 new species of earthworms is a reminder that there is still a great deal science does not know about freshwater biodiversity. Many of these worms make their homes in rice fields that are regularly tended by people, yet they were long overlooked–even though they may play an important role in soil health.


Brian Clark Howard covers the environment for National Geographic. He previously served as an editor for and E/The Environmental Magazine, and has written for Popular Science,,,, Yahoo!, MSN, and elsewhere. He is the co-author of six books, including Geothermal HVACGreen LightingBuild Your Own Small Wind Power System, and Rock Your Ugly Christmas Sweater.