SANYA, May 10 (Xinhua) -- Researchers have discovered several rare species of whales and dolphins in the South China Sea during a scientific investigation that ended Friday.

Researchers have found rare sperm whales and striped dolphins in the area after a 14-day investigation covering 2,500 km. Mother and baby sperm whales and beaked whales have been observed, which indicates a possible habitat.

The investigation was conducted in an area about 400 km long and 200 km wide offshore of south China's island province of Hainan.

Li Songhai, a researcher with the Institute of Deep-sea Science and Engineering, Chinese Academy of Sciences, said the investigation aims to gain insight into the formation, distribution and living habits of the whales in this area.

The researchers spotted 27 groups of whales, including seven identified species of whales and dolphins, Li said. The other two species are yet to be identified.

Li said the investigation results show the biodiversity of the whales in the South China Sea, which is of great significance to the study and protection of whales.