Earthworms are simple, commonplace creatures, are of greater economic value to human beings in different ways. Our earth would be an afar different place without them. They have both useful and harmful aspects of mankind.
Useful effects of Earthworm
- They are beneficial but sometimes they may damage the young and tender plants.
- They are good friends to the gardener and framers as they are continually plowing and manuring the soil.
- They improve the fertility of the soil in different ways because of their habit to burrow and swallow the earth.
- Their burrow and swallow permit both aeration and quick absorption of water which makes it easier downwards growth of the root.
- They also bring subsoil to the surface which is still finer and rich in organic matters.
- Grinding of soil in their gizzards constitutes an effective kind of soil ‘cultivation’.
- Earthworms are continuously dragging dead leaves into their burrows, partly to eat and partly to make the underground retreat more comfortable. They are only partially digested, and their remains are mixed with casting (adding humus to soil).
- Excretory wastes and other secretion of earthworm contains nitrate, calcium, magnesium, potassium, and phosphorous which forms the important plant food.
- Charles Darwin has estimated that an acre of the earth is inhabited by nearly 50,000 earthworms which may bring about 18 tons of deeper soil to the surface in 1 year.
- They reduce the alkalinity and acidity of the soil to provide better conditions for plant growth.
- After their death and decomposition, they increase the organic constituents of the soil.
- Thus, they are known as natural plowmen and tillers of the soil.
As a bait and food
- They are used as bait in fishing all over the world.
- Various methods are used to drive them out for burrows for making large collections.
- Various methods include jarring soil by beating a stick driven into it, pouring poisonous chemical solutions, and also using electric current.
- Best food for fish in aquaria.
- A small white earthworm (Enchytraeus albidus) are used to feed fish and small laboratory animals.
- They were used as food by uncivilized people in many parts of the world.
- They are eagerly hunted as food by some birds, notably robins and chickens.
- They are eaten upon by frogs, toads, moles, lizards, small snakes, centipedes, and other predatory invertebrates.
- They were used variously as medicine in the past.
- Ayurvedic and Unani system of therapy suggests that they were used as medicine to cure disease like bladder stones, jaundice, pyorrhea, piles, rheumatism etc.
- Even these days the Chinese, the Japanese, and the Indians are said to use earthworm in various fancy medicine.
- Many people earn their livelihood by catching these worms and supplying to scientific laboratories.
- They are easily obtained ad are a convenient size for dissections.
- They are universally employed for class studies and for investigation in general and comparative physiology.
Harmful effects of Earthworm
- In some cases, they are harmful.
- They may damage the young and tender plants by eating them bit by bit.
- Exceptionally, their burrow may cause loss of water by seepage from ditches in irrigated lands.
- They may also damage the grasslands by making tunnels in the ground when they are present in huge numbers.
- Their casting on sloppy lands tends to be washed away by rain and thus may contribute to soil erosion to a lesser extent.
- Certain species live as external parasites of frogs and man.
- They bring the disease-germs as they bury in the dead bodies of buried animals sometimes.
- They act as intermediate hosts for the completion of life stages of some parasites, such as Tapeworm and gapeworm of chicken and lung nematode of pigs which are directly or indirectly harmful to the mankind
- Some species of earthworm become pests of plants.
- Pheretima elongata is suspected to damage the roots of piper betel in Coimbatore.
- A species of perionyx damages cardamom stem grown on Anamalai Hills.
Video: Economic Importance & Harmful Aspect of Earthworm By Studio Biology.
- Kotpal RL. 2017. Modern Text Book of Zoology- Invertebrates. 11th Edition. Rastogi Publications.
- Jordan EL and Verma PS. 2018. Invertebrate Zoology. 14th Edition. S Chand Publishing.