People visit the Underwater Beauty exhibit at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year. (Photos: Xinhua)

A visitor learns about anemones at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

People visit the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

A beluga whale comes up for a breath at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

Sharks are seen at the Wild Reef exhibit at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

People look at the Wild Reef exhibit at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

People visit the Wild Reef exhibit at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

Visitors take a selfie at the Wild Reef exhibit at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

People visit the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.

Magellanic penguins get fed at the Shedd Aquarium in Chicago, the United States, on Feb. 17, 2020. The aquarium contains 32,000 animals and attracts around 2 million visitors every year.