QINGDAO, April 7 (Xinhua) -- Scientists led by the Ocean University of China have completed the genome sequencing of the scallop, which may help find crucial clues for people to understand animals' origin and evolution.

According to Bao Zhenmin, a professor with the Ocean University of China, about 99 percent of animals on earth are bilaterian, including the scallop. Scientists believed that all bilaterians might have a common ancestor. Due to a lack of fossil records, however, the origin and evolution of bilaterians are disputable.

The sequencing project started in 2012. The scallop was found to have preserved many bilaterian ancestral genes and ancestral groups.

"A near-perfect correspondence was found between 19 scallop chromosomes and the 17 presumed ancestral bilaterian linkage groups, suggesting that scallop may have a karyotype close to that of the bilaterian ancestor," said scientists in an article, which was published on the website of Nature.

"Molluscs have existed for 500 million years," Bao said. "Further investigation of the scallop genome has provided insight into the evolution of the body plan and the eye."

Foreign researchers from Rutgers University of America and Sars International Center for Marine Molecular Biology, Norway, were involved in the study.