A girl reacts as she receives polio vaccine drops during a house-to-house vaccination campaign in Yemen's capital Sanaa, November 10, 2015. (Photo by Khaled Abdullah/Reuters)

A West African Slender-snouted Crocodile is pictured in its enclosure at the zoo of Abidjan, Ivory Coast September 9, 2016. (Photo by Luc Gnago/Reuters)

In this image made available by France's Marine Nationale, the cargo ship TK Bremen sits stranded on a beach near Erdeven, France, on December 16, 2011, spilled fuel oil fouling the water. (AP Photo/Mael Prigent, Marine Nationale)

Australian Aboriginal hunter Marcus Gaykamangu of the Yolngu people, carries an Australian native lizard called a goanna over his shoulder as he walks away from a billabong near the “out station” of Yathalamarra, located on the outksirts of the community of Ramingining in East Arnhem Land November 22, 2014. (Photo by David Gray/Reuters)

An army tank fires during a firefight against militants linked to al Qaeda near the southern Yemeni city of Zinjibar May 30, 2012. (Photo by Reuters/Yemen's Defence Ministry)

Performer Zhang Yashu from a Chinese ballet company perform during a photo shoot in front of the Australia's iconic landmarks Opera House (L) and Habour Bridge in Sydney on February 17, 2014. One of China's celebrated dance campanies is bringing one of the country's biggest ballet production to Australia for a series of performances in Sydney and Melbourne. (Photo by Saeed Khan/AFP Photo)

Russia's Maria Stavitskaia performs during the ladies short program at the Rostelecom Cup ISU Grand Prix of Figure Skating in Moscow November 14, 2014. (Photo by Grigory Dukor/Reuters)

A visitor feeds a food pellet to a giraffe in the Giraffe Centre in Nairobi, Kenya January 15, 2017. (Photo by Goran Tomasevic/Reuters)