At a water temperature of 21-24°C, the fertilized egg undergoes the first cleavage in approximately 0.5 hour; in 12 hours it develops to the blastocyst stage and rises to the surface; in 20 hours, the blastocyst ruptures; in the 24 hours to the gastrulation After the second day to the four-wool larval stage, the digestive system is complete, and begins to feed, and it develops to eight wrists in 10 days. On the 13th day, the urchin primordium appears; on the 20th day, three fork spines appear. The batch of 5 tubes stretched out. This meant that the embryonic period of sea urchins was over and entered the larval stage.
In the sea urchin primordia, in addition to the internal growth and differentiation, the most easily observed is the appearance of the first batch of five tubes that grow into the body and penetrate the body surface out of the body. The juvenile sucks the end of the tube and sucks it on the bottom. As a new movement organ, the sea urchin begins to live in camp life. The structure of the wrists and other structures of the larvae gradually shrinks as the metamorphosis progresses, eventually forming a five-radiation juvenile sea urchin that develops from fertilized eggs to complete metamorphosis and forms juvenile sea urchins. The time is about 20 days.
In the sea urchin primordia, in addition to the internal growth and differentiation, the most easily observed is the appearance of the first batch of five tubes that grow into the body and penetrate the body surface out of the body. The juvenile sucks the end of the tube and sucks it on the bottom. As a new movement organ, the sea urchin begins to live in camp life. The structure of the wrists and other structures of the larvae gradually shrinks as the metamorphosis progresses, eventually forming a five-radiation juvenile sea urchin that develops from fertilized eggs to complete metamorphosis and forms juvenile sea urchins. The time is about 20 days.