August 5, 2015

British scientists reported that earthworms have “detergent” in their digestive systems that enables them to dine on poisonous plants without harm. Earthworms, also called night crawlers, are common worms found in moist, warm soil throughout the world. Earthworms are important decomposers—that is, living things that break down dead plant material into simple nutrients. The nutrients go back into the soil and are used by plants.

Researchers at Imperial College, London, isolated several unique chemical compounds from the digestive tracts of 14 earthworm species. The scientists used a technique called imaging mass spectrometry (IMS) to examine cross sections of earthworms at an extremely small scale. They identified several unique chemical compounds in earthworms called surfactants. Surfactants consist of molecules that attach themselves to and surround and isolate dirt and certain other molecules until they can be excreted or washed away. Most common detergents and soaps use surfactants as cleaning agents.

The earthworm’s body is made up of segments. World Book diagram by Margaret Estey

Scientists found that these surfactants in earthworms neutralize and counteract toxic compounds called polyphenols made by plants. Plant polyphenols have many functions. Some polyphenols are produced by plants to help defend against plant-eating animals. These polyphenols interfere with digestion in a plant-eating animal’s gut. Dead plants retain these chemicals even as they fall to the ground. This makes even the remains of poisonous plants unpleasant eating for most animals. The surfactants in the earthworm’s gut, however, enable the worm to dine on these remains without harm.

Other World Book articles:

• Soil
• Worm