An undercover police officer, who had been marching with anti-police demonstrators, aims his gun at protesters after some in the crowd attacked him and his partner in Oakland, California December 10, 2014. Police said more than 100 demonstrators marched in Berkeley, California, which has a history of social activism. Under cloudy skies, turnout was smaller than earlier in the week, when demonstrators in the area threw rocks at police and shut down a major freeway. (Photo by Noah Berger/Reuters)

Arctic wolves in their new enclosure in the wildlife park in Hanau, Germany, 10 February 2015. The pack is one of the park's main attractions, which specializes in local and European breeds. (Photo by Boris Roessler/EPA)

A woman rides a mini bicycle through crowds of Santa costumes in a park during the annual SantaCon on December 10, 2016 in London, England. The event sees hundreds of people walking the streets of London and drinking alcohol in Father Christmas and other festive costumes. (Photo by PA Wire)

Nuns react at the arrival of Pope Francis at the St. Mary's school to attend a meeting of clergy and religious in Nairobi, Kenya, 26 November 2015. Pope Francis is on a six days visit that will take him to Kenya, Uganda and the Repulic of Central Africa from 25 to 30 November. (Photo by Daniel Dal Zennaro/EPA)

A sun bear is offered chocolate by a visitor in its enclosure at a zoo in Bandung on January 18, 2017. Animal rights activists on January 18 demanded the closure of an Indonesian zoo after skeletal sun bears were pictured begging for food from visitors and eating their own dung. (Photo by Timur Matahari/AFP Photo)

Visitors view Patricia Piccinini's “The Embrace” artwork during the “You Know Who” exhibition at the Abdulmecit Efendi mansion in Istanbul, Turkey, 27 September 2022. The exhibition, which by the organizers is described as questioning “the representation of the unknown in contemporary art, based on the symbolic world of the supernatural and unknown in the Byzantine period”, is shown from 20 September until 11 December 2022. (Photo by Erdem Sahin/EPA/EFE/Rex Features/Shutterstock)

Juno, a Beluga whale, greets a young viewer at the Mystic aquarium in Connecticut, USA on December 5, 2015. (Photo by Tim Clayton/Corbis)

A demonstrator is detained during May Day rallies in Santiago May 1, 2013. (Photo by Ivan Alvarado/Reuters)