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Research explains earthworm digestion

Worms play a vital ecological role in returning organic matter to the soil.

By Brooks Hays
Research explains earthworm digestion
Earthworms and their unique digestive system play a vital ecological role, returning decaying plant matter and its leftover nutrients to the soil. Photo by Oksana Bratanova/Shutterstock

LONDON, Aug. 4 (UPI) -- It's one of science's great mysteries: How do the entrails of earthworms process all that plant matter?

Now, thanks to new research out of the Imperial College London, we now know how worms eat all those leaves. The key, scientists say, is a class of molecules called drilodefensins.

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Plants produce a class of molecules called polyphenols, which protect plants from UV rays, give them their colors and serve as infection-shielding antioxidants. They're also toxic to many herbivores, keeping plants from being eaten.

Drilodefensins are able to counteract the toxicity of polyphenols.

When studying the molecular makeup of earthworm guts using advanced imaging technology, researchers found that the more polyphenols included in a worm's diet that greater the amount of drilodefensins produced.

Worms play a vital ecological role in returning organic matter to the soil.

"Without drilodefensins, fallen leaves would remain on the surface of the ground for a very long time, building up to a thick layer," researcher Jake Bundy said in a press release. "Our countryside would be unrecognisable, and the whole system of carbon cycling would be disrupted."

Bundy is co-author of a new study on the subject, published this week in the journal Nature Communications.

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"We've established that earthworms, referred to as 'nature's ploughs' by Charles Darwin, have a metabolic coping mechanism to deal with a range of leaf litter diets," added Dave Spurgeon, researcher at the Center for Ecology and Hydrology. "In this role, drilodefensin support the role of earthworm as key 'ecosystem engineers' within the carbon cycle."

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