Earthworm Characteristics and Ecology

Earthworm characteristics

• Earthworms have segmented bodies covered in sleek and slimy skin.
• Over 7,000 different species exist.
• They are found in temperate and tropical soils worldwide.
• Earthworm sizes range from one inch to 5.9 feet.
• The South African giant earthworm reached a length of 21 feet in 1967.

Earthworm diet and role in soil fertility

• Earthworms are decomposers consuming dead plants and roots in soil.
• They can consume their body weight daily.
• They excrete worm castings, nutrient-rich materials, beneficial for plant growth.
• Worm castings effectively fertilize soil.
• A recent study estimated that earthworms are responsible for 6.5% of global food production (approximately 140 million tons annually), comparable to Russia's annual grain harvest.

Earthworm impact on soil structure and water absorption

• Earthworms burrow through soil, improving aeration and mixing organic matter.
• Tunneling enhances drainage, allowing rainwater absorption.
• Earthworm burrowing creates channels that loosen and aerate the soil, allowing water to drain and be stored underground.

Consequences of earthworm disappearance

• Without earthworms, dead plant matter accumulates, reducing soil nutrient levels.
• Plant growth suffers due to nutrient deficiencies, possibly leading to food shortages.
• Soil compaction and dryness hinder plant growth without burrowing.
• Inefficient water absorption in compacted soil results in flooding.

Earthworm role in the food chain

• Earthworms are a critical food source for animals such as robins, foxes, toads, centipedes, and crayfish.
• Earthworm disappearance disrupts the food chain, impacting relying organisms.

How to explore a worm's world

• Adult supervision is recommended.
• Use a magnifying glass or phone magnification app.
• Seek out damp soil after rainfall.
• Observe a worm using magnification.
• Identify the worm's head and tail.
• Look for dead plants as food sources.
• Search for worm castings, resembling small black footballs.

Earthworm impact on plant growth

• Earthworms significantly impact plant growth, especially in developing countries.
• In Sub-Saharan Africa and Latin America, earthworms increased grain yields by 10% and 8% respectively.
• This is likely due to farmers' reliance on earthworm-rich organic matter in regions with limited chemical inputs.
• Earthworms improve nutrient availability to plants by churning soil organic matter.
• Studies show earthworms boost crop yields.

Earthworm and Microplastics

• Earthworms can protect plants from microplastic pollution.
• When present in microplastic-contaminated soil, earthworms allowed tomato plants to thrive and repel pests, possibly through strengthening plant immunity.