A white Bengal tiger cub plays with its mother in a zoo in the Siberian city of Novosibirsk, about 2,800 kilometers (1,750 miles) east of Moscow, Russia, Tuesday, April 21, 2015. Two blue-eyed Bengal tiger cubs were born in March to a couple of white tigers at Novosibirsk zoo. (Photo by Ilnar Salakhiev/AP Photo)

14 week-old twin polar bear cubs play during their first presentation to the media in Hellabrunn zoo on March 19, 2014 in Munich, Germany. The male and female twins were born on December 9, 2013 in the zoo. (Photo by Alexandra Beier/Getty Images)

An adult chimp plays with a young chimp at Chimp Haven in Keithville, La., Monday, February 18, 2013. One hundred and eleven chimpanzees will be coming from a south Louisiana laboratory to Chimp Haven, the national sanctuary for chimpanzees retired from federal research. (AP Photo/Gerald Herbert)

An actor carries a cross as he plays the role of Jesus Christ in a re-enactment of the Via Crucis (Way of the Cross) during a Holy Week procession, in preparation for Good Friday celebrations, in Luque, Paraguay, on March 27, 2013. Holy Week is celebrated in many Christian traditions during the week before Easter. (Photo by Jorge Adorno/Reuters)

Swedish brown bears “Fred” and “Frode” play in the snow on January 30, 2014 at the Natur- und Umweltpark (NUP) animal park in Guestrow, northeastern Germany. Despite of icy temperatures, the bear brothers took a break from their winter rest. (Photo by Bernd Wuestneck/AFP Photo/DPA)

A man playing the part of a zombi pretends to rise from the dead from inside a coffin at a Carnival parade in Jacmel, Haiti, Sunday, February 23, 2014. The pre-Lent festival began in the streets of this town known for its arts to kick off Haiti’s Carnival festivities. (Photo by Dieu Nalio Chery/AP Photo)

Turkana boys play with rifles in a village inside the Turkana region of the Ilemi Triangle, northwest Kenya December 21, 2014. The Ilemi Triangle is a disputed region in East Africa, claimed by South Sudan and Kenya, bordering also Ethiopia. The dispute arose from unclear wording of a 1914 treaty which tried to allow free movement of the Turkana people, nomadic herders who had traditionally grazed the area. (Photo by Goran Tomasevic/Reuters)

A winter swimmer, wearing a Santa Claus hat to celebrate the upcoming Christmas, reacts as he plays on a frozen lake at a park in Shenyang, Liaoning province, December 22, 2014. The characters on the hat read: “Shenyang Winter Swimming”. (Photo by Reuters/Stringer)