How do earthworms move underground?

Earthworms are quite familiar creatures, especially in rural areas. On average, earthworms are 10-35 cm long. Earthworms play an important role in agriculture because they loosen the soil and increase soil fertility. In addition, earthworms are also food for livestock and poultry. Although they are invertebrates, they are still able to move underground. So how do earthworms move?

Earthworms are invertebrates but they can still move easily.

Worms ready to crawl

Earthworms have a tube-within-a-tube body structure, segmented externally with corresponding internal segments, and typically have setae on all segments.

First, the earthworm must extend the front of its body using its muscles. As the front lengthens, bristle-like structures (called setae) protrude from the front of the worm and anchor themselves in the soil. The setae now act as an anchor for the earthworm to pull its rear end forward.

Shrink to puff out the head, shrink the tail

When the hind part of the body has moved forward, the earthworm retracts the setae in the front part, and inserts the setae from its hind part into the soil. Now, the setae from the hind part act as an anchor for the earthworm to push its hind part forward. This process is repeated to help the earthworm move. It can be seen that the earthworm moves in the soil thanks to the elasticity of its body, combining the silk rings and the whole body.

Characteristics of earthworms

Earthworms feed on organic matter including plants, protozoans, larvae, rotifers, nematodes, bacteria, fungi and other microorganisms. Earthworms have the following external characteristics: bilaterally symmetrical body, with a formal body cavity. The body is long, with many segments, developed muscles for elasticity, the head has a mouth, and the tail has an anus.

At the head, there is a ring of silk around each segment, used to press against the soil when crawling (earthworms do not have legs). The worm's body has mucus, a thin layer of skin, the skin is always moist to exchange gases through the skin and reduce friction when crawling in the soil. When searching for food, if the soil is dry and hard, the worm secretes mucus to soften the soil and then swallows the soil into the mouth. The worm's eyes are reduced, adapting to life crawling in the soil.

Worms are hermaphrodites. Each worm has both male reproductive organs (testes) and female reproductive organs (ovaries). When reproducing, two worms touch their heads and exchange semen. After the two bodies have been separated for 2-3 days, the genital girdle peels off and slides forward, picking up eggs and semen along the way. When it slides off the body, the girdle ties together at both ends to form a cocoon. Within the cocoon, after a few weeks, the eggs hatch into young worms.

Effects of earthworms on soil and plants

Earthworms are considered as “workers” that help loosen the soil, helping the soil retain water better. At the same time, thanks to earthworms, the space in the soil allows plant roots to be exposed to more oxygen. Earthworm waste is a very good natural fertilizer for plants. Earthworm excrement can help plants avoid some harmful insects.

Tuyet Anh (Source: Synthesis)

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