The earthworms have been made into two parts, why are they still alive?

Earthworms are this kind of bug. Headless and tailless. If a very long earthworm breaks it into ten pieces, it will not die.

The earthworm is cut into two pieces and still alive.

After the earthworm is cut in two, the muscle tissue on the section will contract strongly, and some muscle tissue will quickly dissolve, and then form a new cell mass. At this time, the white blood cells contained in the blood are also concentrated on the cut surface at the same time, forming a special embolism, which allows the wound to close quickly.

Moreover, its mesoderm cells also have a very strong ability to differentiate, when it has a wound, the original cells that are originally located in the diaphragm in the body cavity have not yet differentiated, quickly move to the wound section, and connect with their own dissolved muscle cells, forming a nodular-like bulge on the section surface, which is called regeneration bud.

Morphological structure of earthworms:

The body is segmented but not divided, the verrucous feet are vestigial, and the body surface is bristled. Hermaphroditic, 1-2 pairs of gonads, reproductive ducts of body cavity origin, rings (clitellum) appear on the body surface when sexually mature, mutual insemination can be done during mating, eggs are laid in the rings, and after falling off, egg cocoons are formed, and they develop directly.

The bristles are simple, 8, sometimes many, arranged in a ring, 1-2 pairs of sperm nests, usually at 10-11 nodes, male reproductive pores one pair, located on 2 or more somites after the posterior sperm nest, i.e. after 14 nodes. A pair of ovaries, located in the 13th segment, with a thicker annular band and less yolk.

The chromosome 2n=22 chromosome of the earthworm has been used to identify the chromosomal karyotype analysis method in China, which is exactly the same as the artificially bred earthworms "Taiping No. 2" and "Beixing No. 2".

Why doesn't the earthworm die after the earthworm is split into two segments?

The earthworm is a special regenerative animal, and after the earthworm is divided into two segments, each part will grow into a complete individual. Many lower animals have a strong ability to regenerate. Planarians are cut in half or earthworms are cut into many segments, each of which grows into a complete individual.

In distress, geckos will cut off their tails to survive, crabs will cut off their limbs and abandon their chelas, and these lost parts will grow back after a period of time, and have the same function as the original limbs. The earthworm breaks into two segments that contain the "reproductive ring" and regenerates a complete individual, and it does not matter whether the section containing the "reproductive ring" is the head or the tail. Generally, the body segment of earthworms begins to regenerate in about 10 days, and it has the ability to regenerate from beginning to end.

However, the regeneration ability of earthworms in different body segments is different, and the regeneration rate of body segments without head and tail is faster than that of body segments without heads and tails. Among them, the head and tail of the headless and tailless earthworm body segment can be regenerated, but the regeneration rate of the tail is significantly higher than that of the head. The number of earthworm segments left after shearing has a great impact on the survival rate of earthworms, and the higher the number of segments left, the lower the mortality rate of earthworm segments.