Earthworm: Classification, Taxonomy, Characteristics, Reproduction and Importance For class 11th and NEET


Kingdom: Animalia

Phylum- Annelida


Order- Opisthopora

 Genus- Pheretima.  

Earthworm Taxonomy

Earthworms are categorised as animals in the Phylum Annelida Class-Clitellata Order- Opisthopora Genus- Pheretima. There are over 1800 species of earthworms in this phylum, which are divided into five families and found all over the world. Earthworms can be as small as a few millimetres long or as large as 3 feet, but the most frequent species are only a few inches long. Nightcrawlers, Field worms, Manure worms, Red worms, and some common earthworm species.


While primitive, the earthworm’s neurological, circulatory, digestive, muscular, and reproductive systems are well-developed. The ringing or segmentation of the body, which is not just external but also involves virtually all of the interior anatomy, is the most obvious external feature. The first segment of the earthworm, the anterior end or head, consists of the mouth and the prostomium, a lobe that serves as a covering for the mouth as well as a wedge to force open fissures in the dirt into which the earthworm can crawl. Setae (bristles) are little hair-like structures found on each segment. These can be extended or retracted, and their main purpose is to allow mobility. Earthworms do not have specific breathing apparatus. The respiratory exchange takes place at the surface of the organism.


Habitat and habitat: These can be found in the soil, but not in Sandy or humus-deficient soil. Mountain, clayey, and acidic soil are all good places to look for them.

Distribution: Cosmopolitan

Shape: The body is cylindrical and elongated, having a pointed anterior end and a blunt posterior end. ‘The body shape is well suited to burrowing life.’

Pigmentation: It has a dark brown pigmentation to it.

Segmentation: The body is separated into segments called metameres by transverse furrows.

The number of segments: The number of segments ranges from 100 to 120.

 Length: Approximately 150 mm in length

Breadth: 3 to 5 mm in width

Clitellum: It is a thick girdle that resembles a forwardly located area and contains only three body segments (14 to 16). It comes together to make a full ring.

 Setae: A ring of tiny covered chitinous setae can be seen ventrally in the middle of each segment using a hand lens. Setae have locomotory abilities. Setae are absent from the first segment, the last segment, and the cliteiar area.

Mouth: The mouth is a Crescentic opening in the first segment that moves ventrally to a fleshy prostomium. Two pairs of papillae (genital or copulatory) There are one pair each on the ventral surface of the 17th and 19th segments.

Female genital opening: The female vaginal entrance is located in the clitellar area on the ventral side of the 14th segment.

Male genital pore: Two are present on either side of the ventral surface on elevated genital papillae, one on each side of the ventral surface.

Spermathecal pore: The spermathecal pore is found ventral in the intersegmental grooves of segments 5/6, 6/7, 7/8, and 8/9. The anus is lying on the final segment.

Dorsal blood vessel: It extends from the anterior to the posterior end of the dorsal surface.


Although earthworms are hermaphroditic, they rarely self-mate (each individual possesses both male and female reproductive organs.). During mating, two worms share sperm. The clitellum, a prominent, girdle-like structure near the anterior end of the body, produces cocoons in which mature sperm and egg cells, as well as nourishing fluid, are deposited. The sperm cells within the cocoon fertilise the ova (eggs), which subsequently fall off the worm and land in or on the earth. After around 3 weeks, the eggs hatch, and each cocoon produces two to twenty baby worms on average.

The significance of earthworms in terms of soil productivity

The favourable impacts of earthworms on soil qualities have been noted by several researchers. There are a few significant impacts.

Earthworm in Soil

1. Earthworms help decompose organic leftovers in the soil by releasing elements including carbon, nitrogen, sulphur, and other nutrients.

2. The digestive juices and increased microbial activity in the casts (droppings) tend to solubilize inorganic plant nutrition components that are found in inorganic soil minerals.

3. The earthworm’s considerable burrowing increases soil aeration.

4. Burrowing can help boost the amount of water that gets into the soil.

5. In natural conditions, the earthworm will feed on organic litter on the surface and deposit its casts in the plant root zone. Plant nutrients are released as the partially decomposed leftovers undergo additional microbial breakdown.

6. Earthworm manure can be utilised as an organic soil amendent or fertiliser in a potting mixture. Its nutritious value will be mostly determined by the nutrient content of the organic items used, and it might be compared to compost made from the same organic waste. When worms are harvested, however, a significant amount of nutrients are taken from the leftovers.

READ ALSO: Role of Earth Worm in Soil Fertility

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