Coral can reproduce sexually or asexually. Sexual reproduction of coral has the advantages of strong reproduction, high genetic diversity and no damage to the mother coral. Coral eggs and sperm are produced by gonads on the diaphragm and discharged into the sea through the mouth. Fertilization usually occurs in seawater and sometimes in the gastric circulation cavity. Usually fertilization only occurs between eggs and sperm of different individuals. The fertilized egg develops into a floating larva, which is covered with cilia and can swim. After a few days to weeks, it will be fixed on the solid surface and develop into a hydra. It can also be propagated by budding, which will not be separated from the original hydra after budding. New buds keep forming and growing, so they breed into groups. When the new hydra grows and develops, the old hydra under it dies, but the skeleton remains in the population. Soft corals, gorgonian corals and blue corals live in groups.

Coral is a marine invertebrate of Polypodiaceae among echinoderms. Characterized by calcareous, horny or leathery endoskeleton or exoskeleton. The word coral also refers to the bones of these animals, especially calcareous ones. Coral body consists of two layers of germ layers: the outer cell layer is called ectoderm; The cell layer inside is called endoderm. There is a thin mesothelium between endoderm and ectoderm, and there is no cell structure. Food enters through the mouth and food residue is discharged from the mouth. This animal has no head and trunk, no nerve center, only a diffuse nervous system. When stimulated by the outside world, the whole animal body will react. Its lifestyle is free floating or fixed in the seabed habitat.