Earthworms: Unique Gut Metabolites Protect Them From Plant Toxins

Earthworms seem relatively harmless. Reddish-gray in color, the night crawlers are indigenous to Europe but are now abundant in North America and even parts of Western Asia, too. Furthermore, they're typically only seen at night, stretching out at just about 7 or 8 centimeters in length.

New findings published in Nature Communications show that these tube-shaped insects actually eat decaying plants. What would be considered a normally hazardous amount of toxins for other insects is actually possible in earthworms as certain guttural molecules actually protect them.

"Earthworms possess a class of unique surface-active metabolites in their gut, which we term ‘drilodefensins', researchers noted, in a news release.

In this study, researchers found drilodefensins in the guts of 14 earthworm species. However, they did not find similar results in leeches and sewage worms.

Researchers noted how this insect comes equipped with a specific kind of molecule that protects it from dead and decaying plants that carry toxins that would make normal insects unable to digest them or even kill them. Earthworms, on the other hand, can live normally, returning carbon to the soil in which they dwell.

Plants make up chemicals known as polyphenols that act as antioxidants and give them their colors. However, they also act as a shield that inhibits digestion in herbivores.

Fortunately, for earthworms, they can munch up fallen leaves and other plant material without it harming them, meanwhile helping to give back carbon to the soil.

"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," study co-author Dave Spurgeon, of the Centre for Ecology and Hydrology, said in the release. "In this role, drilodefensin support the role of earthworm as key "ecosystem engineers" within the carbon cycle."

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