Introductory Chapter: Earthworms - The Ecological Engineers of Soil

Abstract

Intimacy of human with earthworm has a long history. Hunter-gatherer mode of life style of primitive human faced the challenge of uncertainty of food for the alleviation of hunger. Primitive societies are thought to be solely dependent on collection of natural resources from forest, river, and other water bodies for survival. Such resources included both plants and animals with nutritional and medicinal significance. Early human invented, learnt, and improvised agricultural technologies in different regions of the planet. They observed that the silted river plains with adequate moisture content are extremely fertile for the growth of various crops. While practicing agriculture, they might have observed these moist bodied worms of soil and their casting heaps along the soil surface. During tilling, they unearthed and observed these worms, which are able to penetrate soil without much effort as and when necessary. They befriended these ‘down to earth’ worms, which were innocuous and beneficial for agricultural practice. Earthworms are the true friends of farmers and are capable of increasing porosity and fertility of agricultural soil by their natural activity. Traditional farmers rely on their indigenous knowledge base and experience, and care these worms for their professional interest. These slow moving, yet highly dynamic soil annelids are considered as one of the beneficial animals to human and an indicator of the general health of soil. Earthworms did not evolve vision and still are uniquely sensitive to microlevel shift in the quality of soil and other environmental parameters. Their sensitivity toward soil contaminants and selected ecological cues enabled them to act as source of biomarkers of toxin exposure to soil and water.