Behaviour: Mammals category. Giant Gathering by Tony Wu, USA. Dozens of sperm whales mingled noisily off Sri Lanka’s northeast coast, stacked as far down as Tony could see. This was a congregation of dozens of social units, like a gathering of the clans. Aggregations like this could be a critical part of the whales’ rich social lives but are rarely reported. Some two thirds of the population was wiped out before commercial whaling was banned in 1986. This kind of major gathering could be “a sign that populations are recovering”, says Tony. (Photo by Tony Wu/Wildlife Photographer of the Year 2017)

A massive, 8 metre tall sculpture of Marilyn Monroe, frozen with her dress blowing up, was on display at a shopping mall in downtown Dalian city, northeast China's Liaoning province, on Tuesday, November 14, 2017. The sculpture is a replica of Seward Johnson's Forever Marilyn in Chicago. (Photo by Imagine China/Rex Features/Shutterstock)

Riot police clash with demonstrators protesting against proposed pension reforms outside the Congress in Buenos Aires on December 18, 2017. Protesters angry at proposed pension and welfare reforms attacked police close to Argentina's congress building in Buenos Aires on Monday, the second protest in a week to turn violent. Activists lobbed stones, bottles and firecrackers at police as huge crowds demonstrated against pension reforms proposed by the center-right government of President Mauricio Macri. (Photo by Eitan Abramovich/AFP Photo)

Khansa, an eight month old critically endangered Bornean orangutan shows off it's two front-teeth, at the Singapore Zoo on Thursday, January 11, 2018 in Singapore. The Singapore Zoo is active with its breeding programs as part of its wildlife preservation efforts. This is the Zoo's 46th successful orangutan birth. (Photo by Wong Maye-E/AP Photo)

A college girl takes part in the Holi festival celebrations in Bhopal, India, 19 March 2019. Holi is celebrated on the full moon day and marks the beginning of the spring season. Holi will be celebrated as the Hindu spring festival of colors across the country on 21 March. (Photo by Sanjeev Gupta/EPA/EFE)

Erica Daly, a District Nurse Team Leader at Mersey Care NHS, stands in front of the “Liver Bird Wings”, an artwork by Paul Curtis on a wall within Liverpool's Baltic Triangle on April 29, 2020. (Photo by Peter Byrne/PA Images via Getty Images)

Visitors browse in the starry Art Museum. Shanghai, China, May 13, 2020. The exhibition hall uses a large number of mirror devices, combined with the layout of acousto-optic, to create a visual scene and spatial effect. (Photo by Costfoto/Barcroft Media via Getty Images)

Men carry a dog, wearing a costume and seated on a stool, as a form of respect as they believe that dogs found water for their ancestors, during a local festival for the Miao ethnic minority in Jianhe county, Guizhou Province, China, August 14, 2016. (Photo by Reuters/China Daily)