A zookeeper feeds a hippopotamus with a watermelon in its enclosure in Belgrade's zoo, Serbia, July 20, 2015. Temperatures in Serbia have risen up to 40 degrees Celsius (104 degrees Fahrenheit), according to official meteorological data. (Photo by Marko Djurica/Reuters)

Newborn sea lion “Kaya” crawls at the enclosure at the zoo in Wuppertal, Germany July 23, 2015. Kaya was born on July 4, 2015 in the zoo, officials said. (Photo by Ina Fassbender/Reuters)

“My name is In Cherl Kim. I'm a PR manager of Samsung Everland. Everland is a largest theme park in South Korea. Everland has a variety of attractions and flower garden and entertainment. Among other things, Everland zoo is very unique place!” – In Cherl Kim. Photo: Ring tailed lemur. (Photo by In Cherl Kim)

Baby clouded leopards, born early in March 2015, are presented by zoo keepers at the Olmense Zoo in Olmen, Belgium, April 16, 2015. The clouded leopard is an endangered species with only some 10,000 specimen remaining on earth, said Robby Van der Velden, a biologist at the Olmense Zoo. (Photo by Yves Herman/Reuters)

“The National Portrait Gallery, London's annual photographic portrait prize was established in 2003 as the Schweppes Photographic Portrait Prize. In the years 2006 and 2007 it was referred to simply as the Photographic Portrait Prize, while from 2008 new sponsors have resulted in the name, Taylor Wessing Photographic Portait Prize”. – Wikipedia. Photo: “Tic Tac and Tootsie (twin sisters Carrol and Shelly McKean)”. Taylor Wessing photographic portrait prize 2010. (Photo by Jeffrey Stockbridge)

The first jaguar litter since 1975 was born at the Milwaukee County Zoo to Stella and Pat on November 13, 2013. The litter was on public display for the first time on March 13 when the jaguar baby's names were released. Belize schoolchildren named one Zean, which is the end of Belizean, and a public contest named the other B'alam, which means "great and powerful king" in Mayan. Photo: Stella the mother and her cub Zean rest together at The Milwaukee County Zoo. (Photo by Rick Wood)

Azalea, whose Korean name is “Dalle”, a 19-year-old female chimpanzee, lights a cigarette at the Central Zoo in Pyongyang, North Korea on Wednesday, October 19, 2016. According to officials at the newly renovated zoo, which has become a favorite leisure spot in the North Korean capital since it was re-opened in July, the chimpanzee smokes about a pack a day. They insist, however, that she doesn’t inhale. (Photo by Wong Maye-E/AP Photo)