The only giant panda twins in the US were officially named Ya Lun and Xi Lun at the cubs' 100-day naming celebration on Monday at Zoo Atlanta.

Ya means "elegant", and Xi means "happy". Lun honors Lun Lun, mother of the twins. Together, the monikers mean "Lun Lun's elegant and happy daughters".

The winning names are from among seven sets supplied by conservation partners in Chengdu, in Southwest China's Sichuan province.

Ya Lun (Cub A) and Xi Lun (Cub B) earned just over 11,000 of the more than 23,400 votes cast by panda fans around the world from Nov 21 to Dec 4.

"We're thrilled to announce two beautiful and meaningful names for two healthy, thriving, 100-day-old giant panda cubs," said Raymond King, president and CEO of Zoo Atlanta.

"This is a celebration we share with the City of Atlanta, our longtime partners at the Chengdu Research Base of Giant Panda Breeding in China, and with our Zoo Atlanta family, which includes friends and fans from around the world. As we wish Ya Lun and Xi Lun well today, we celebrate the future of their species together," King continued.

The 100-day celebration, which has been followed with all seven Atlanta-born giant pandas, is an ancient Chinese tradition that holds when a child reaches the 100th day of life, he or she has survived the fragility of infancy and may be considered on track for a successful future.

Ya Lun's and Xi Lun's festivities opened with a performance by the Wesley International School Choir. The name revelation was followed by a traditional lion dance by the Chien Hong School of Kung Fu.

Born on Sept 3, 2016, the twins are the second set of twins for Lun Lun and the sixth and seventh offspring of Lun Lun and Yang Yang.

Ya Lun and Xi Lun play important individual roles in one of Zoo Atlanta's longest-term conservation collaborations. Giant pandas represent the Zoo's most significant financial investment in wildlife conservation, with more than $10 million contributed in sustained support for wild giant pandas.

According to Rachel Davis, director of communications at Zoo Atlanta, all of the giant pandas at all four US zoos housing them are owned by China.

"As part of our loan agreement with China, all of the offspring of our adult pair, Lun Lun and Yang Yang, do eventually travel to China when they are around 3 years old," Davis said.

"A total of five giant pandas that were born to Lun Lun at Zoo Atlanta have traveled to China thus far: Mei Lan, Xi Lan, Po, and twins Mei Lun and Mei Huan. The new twin cubs will eventually travel to China as well, although they will have a few years to grow up with us here in Atlanta before it's time for them to do that."

Due to a conservation effort in China and around the world at institutions such as Zoo Atlanta, the International Union for the Conservation of Nature (IUCN) downgraded the giant panda's status from "endangered" to "vulnerable" in September, according to the zoo.

However, the species remains heavily reliant on conservation programs. Fewer than 1,900 giant pandas are estimated to remain in the wild in Sichuan, Shaanxi and Gansu provinces, where they face continuing threats from habitat fragmentation. Habitat loss as a result of deforestation and other human activities.

More than 1,200 of China's remaining wild giant pandas live inside nature reserves, eight of which are supported by Zoo Atlanta.

Xie Fei, culture counselor from the Chinese Consulate General in Houston, attended the ceremony and praised Zoo Atlanta for its conservation efforts:

"The zoo has over the years provided valuable support and expertise for the conservation of the giant panda and its habitats in China, which is highly appreciated by the Chinese government and people. The giant panda program exemplifies the China-US cooperation."

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