Earthworms, commonly known as earthworms, also known as eels, are representative of the phylum Oligochaeta. Earthworms are camping carrion life animals, living in a moist environment, to corrupt organic matter for food, living environment is full of a large number of microorganisms but rarely get sick, this number of earthworms in the body of the unique antimicrobial number of the immune system is related to

In the scientific classification, they belong to the order of the unidirectional earthworms. The body is cylindrical (as opposed to the cylindrical shape of the nematodes), symmetrical on both sides, and segmented: it consists of more than 100 segments, each of which, after the eleventh, has a dorsal pore in the center of the back; it has no skeleton and is an invertebrate, with a bare body surface and no cuticle. All segments of the body, except the first two, have setae. Male and female, heterozygous fertilization, reproduction by the ring band to produce egg cocoons, reproduction of the next generation. Currently known earthworms are more than 2,500 species, Darwin in 1881 has pointed out that earthworms are the world's most important animal groups in the history of evolution