As the Hong Kong-Zhuhai-Macao Bridge opened on Tuesday, a group of special guests were spotted by a patrol vessel of the Guangdong Maritime Safety Administration near this world's longest sea-crossing bridge. These special guests - nicknamed the “giant panda of the sea” - are the rare Chinese white dolphin. 

The Chinese white dolphin is under first-class state protection in China. Researchers have identified more than 2,000 Chinese white dolphins in the Pearl River Estuary, the main habitat of this rare species, since 2011.

Although the name might suggest that the animal's color is white, the adult dolphins are usually pink. When the dolphin is first born, their skin is dark grey, and as they grow older, they turn into a lighter grey color and eventually become pink. The pink color is due to the blood vessels underneath the skin.  It is not because of the color in the skin.  

These adorable animals love to live in warm water with temperatures above 15 degree Celsius and a depth of 20 meters on average. Home to the majority of Chinese white dolphins is in China's Pearl River Estuary, which provides them with a comfortable environment as well as abundant food resources. They are often spotted swimming after fishing boats for hours, catching the fish that drop out of the net.

At the same time, the busy water traffic, alongside with pollution at the estuary posed a threat to this vulnerable species. The Chinese government has been putting great efforts in preserving natural habitats for the Chinese white dolphins. Although the Hong Kong-Zhuhai-Macao Bridge is built near the reserve for the Chinese white dolphins, numerous protections have been established in controlling the ecological impact of the bridge.

According to an article posted on ECNS, during the construction period, researchers tracked the species more than 300 times, took over 300,000 photos, identified more than 1,000 Chinese white dolphins, and organized 29 training sessions for a total of 2,544 participants. The number of the bridge's piers was reduced from 318 to 224 amid engineering efforts to protect the creatures.

As a result, the dolphins were not harmed during the construction of the bridge, according to the Hong Kong-Zhuhai-Macao Bridge Administration.