An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida . They occur worldwide where soil, water, and temperature allow.  Earthworms are commonly found in soil, eating a wide variety of organic matter. This organic matter includes plant matter, living protozoa , rotifers , nematodes , bacteria , fungi  and other microorganisms.

Earthworms are commonly referred to as "creepy crawlies" and aren't always thought of as the cutest creatures. But what if you discovered that earthworms have a significant impact on life on the planet?

Earthworms, which feed on soil bacteria, have been found to have a positive impact in the fight against climate change in studies. These microorganisms eat decaying debris and release carbon dioxide into the atmosphere as part of the digestive process. When earthworms eat these microorganisms, the decomposition process produces less carbon than the microbes do. This is significant because global warming raises soil temperatures, which speeds up the decomposition process and releases more carbon into the soil.

Major role of earthworms in environmental protection

1. Earthworms are recycling machines. Simply by eating and pooping, they play an important role in breaking down organic materials and fertilizing the soil (about 1.5 times their body weight a day). The worm cast that emerges from the other end is rich in nutrients and microbes that are good to plants. In comparison to adjacent soil, scientists have found that worm casts contain up to five times the amount of critical nutrients.

A research in Hawaii revealed that substituting vermicompost (compost made from worm casts) for a part of normal fertilizer enhanced tomato and strawberry yields by 30%. Of course, producing large quantities of worm cast is difficult, and vermicompost is still more expensive than commercial fertilizer. However, it's a fascinating example of how earthworms may assist humans.

2. Earthworms are excellent "soil builders." Earthworms loosen and mix up the soil as they move through it, helping to aerate and drain it. This helps minimize flooding and erosion by bringing nutrients to the surface and making the soil more fertile.

3. Earthworms are indicators of soil toxicity and health. They're extremely vulnerable to soil pollutants like pesticide residues or undesired heavy metals (zinc, lead, and other metals), and they're negatively impacted by land use changes like deforestation to make room for intensive farming. As a result, the health of local worms is proving to be a useful tool for determining the impact of various land uses and contaminants.

4.Earthworms are a vital source of nutrition. They are high in protein and nourish a variety of animals, including the European badger.

Reference :

https://www.downtoearth.org.in/news/environment/earthworms-are-more-important-than-pandas-if-you-want-to-save-the-planet-57480