Two chimpanzees share a piece of watermelon at Taronga Zoo on December 23, 2010 in Sydney, Australia. The festive foods were given to the animals as part of the regular enrichment program in place to encourage the animals to forage for food and help improve hunting abilities. (Photo by Rick Stevens/Taronga Zoo via Getty Images)

A tree kangaroo eats slices of watermelon at Taronga Zoo on December 23, 2010 in Sydney, Australia. (Photo by Rick Stevens/Taronga Zoo via Getty Images)

A Chimpanzee eats a slice of watermelon in it's new home at Taronga Zoo on December 2, 2009 in Sydney, Australia. (Photo by Cameron Spencer/Getty Images)

A ten year old polar bear called Tonki eats watermelon and other fruits at the Everland Amusement Park on July 14, 2005 in Yongin, South Korea. (Photo by Chung Sung-Jun/Getty Images)

A ring-tailed coati cools down as it eats a watermelon given to it by its keeper at ZSL London Zoo on July 9, 2010 in London, England. (Photo by Oli Scarff/Getty Images)

A six-year-old male orangutan called Allan eats a piece of watermelon at the Everland Amusement Park on July 14, 2005 in Yongin, South Korea. (Photo by Chung Sung-Jun/Getty Images)