Mr. Ben, a pygmy slow loris, is administed anesthetic during one of Bristol Zoo's in-house veterinary clinic routine health check-up and teeth clean as part of the Zoo's standard animal husbandry and welfare procedure at Bristol Zoo on June 18, 2009 in Bristol, England. (Photo by Matt Cardy/Getty Images)

A woman looks at traditional Ukrainian Easter eggs “Pysanka”, installed as part of the upcoming celebrations of Easter, in central Kiev, Ukraine, April 29, 2016. A pysanka is a Ukrainian Easter egg, decorated with traditional Ukrainian folk designs using a wax-resist (batik) method. The word pysanka comes from the verb pysaty, “to write”, as the designs are not painted on, but written with beeswax. Many other eastern European ethnic groups decorate eggs using wax resist for Easter. These include the Belarusians, Bulgarians, Croats, Czechs, Hungarians, Lithuanians, Poles, Romanians, Serbs, Slovaks, Slovenes and Sorbs. (Photo by Valentyn Ogirenko/Reuters)

Photo taken on September 19, 2015 shows a baby Brazilian opossum at the “Parque Estoril” zoo in Sao Bernardo do Campo of Sao Paulo, Brazil. According to local press, the “Parque Estoril” zoo houses currently 23 orphan cubs of wild animals rescued in the south region of Sao Paulo, victims of illegal wildlife trade or problems caused by urban growth. According to the zoo, all the animals arrived in the last three months, and many of them, not being able to be reintroduced to their natural habitat, will be used as examples in environmental education classes. (Photo by Rahel Patrasso/Xinhua via ZUMA Wire)

Two hippopotamus are fed with pumpkins at the Hanoi Zoo, in Hanoi, Vietnam, 25 October 2018. The zoo has been the home for more than 800 animals of over 90 different species, including three hippopotamus, since it was built in 1976. (Photo by Luong Thai Linh/EPA/EFE)

A zoo employee carries three-month-old female giant panda cub, born to mother Liang Liang and father Xing Xing, on display to the public for the first time at the national zoo in Kuala Lumpur, Malaysia, November 17, 2015. (Photo by Olivia Harris/Reuters)

A Capybara bathes in the hot spring water at the Saitama Children's zoo in Higashi Matsuyama city, Saitama prefecture on December 21, 2014. Seven capybaras in the zoo, originally from South America, enjoyed the hot spring water on the chilly winter day in Japan. (Photo by Toshifumi Kitamura/AFP Photo)

Buyan, a male Siberian brown bear, is given a shower by a zoo employee in his enclosure at the Royev Ruchey zoo in Russia's Siberian city of Krasnoyarsk June 24, 2014. The Siberian city has been experiencing temperatures of around 30 degrees Celsius over the last week. (Photo by Ilya Naymushin/Reuters)

A polar bear fast asleep at London Zoo. (Photo by Fox Photos/Getty Images). 1961