Study on the embryonic and larval development of Perinereis aibuhitensis

The embryonic and larval developments of Perinereis aibuhitensis were observed in 2003 and 2004.The result was that:the fertilized egg appeared green,its size ranged from 175 to 228 μm and had lots of oily granules.The embryonic development of Perinereis aibuhitensis could be divided into 4 stages:cleavage,blastoderm,gastrule and trochophora.The larva began from 3 setiger juvenile and began to be fed at the end of 3-setiger nectochatte;the cilia annulus vanished at the end of 4 setiger juvenile;at the same time the larva began to grovel;the 10-setiger nectochatte was similar to the fully grown worm.When the water temperature was from 25 ℃ to 26 ℃,the time from fertilized egg to 4 setiger juvenile was 118 h,but when the water temperature was from 27.5 ℃ to 32 ℃,the time was 82 h.