From the St. Louis Zoo website: A saddened staff at the Saint Louis Zoo bid farewell to "Hope," a polar bear at the Saint Louis Zoo. Hope was humanely euthanized on March 30, 2009 after exploratory surgery showed advanced signs of liver cancer. Hope was 23½ years old, a popular mainstay at the Zoo since she arrived here in 1986. She was born at Cleveland Metroparks Zoo in November, 1985. In the wild, polar bears live an average life span of 15 to 18 years, and in zoos, the average life span is 20 to 22 years. Zoo veterinarians anesthetized Hope on March 30 because she had shown decreased appetite and activity in the past several days. When an ultrasound showed various-sized masses in her abdomen, she underwent surgery. Liver cancer was advanced and inoperable. "Hope was a longtime favorite of her animal care staff and our visitors," said Steve Bircher, curator of carnivores . "She will be greatly missed. She truly enjoyed swimming in her pool, playing with her boomer ball and other enrichment activities and her 4 p.m. feeding. "We know that Hope held a special place in our community," he added. "We are all saddened by her death."