A giant river otter, the world's largest otter species, looks out of its enclosure at the newly completed River Safari in Singapore, on March 25, 2013. (Photo by Wong Maye-E/Associated Press)

Meerkats are weighed and measured during the ZSL London Zoo 's annual weigh-in on August 22, 2012 in London, England. The height and mass of every animal in the zoo, of which there are over 16,000, needs to be recorded. The measurements are collated in the Zoological Information Management System, from which zoologists can use the data to compare information on thousands of endangered species. (Photo by Oli Scarff)

Rosie the elephants proves to be heavier than her companion and tips the park bench when she tries to sit down. (Photo by Mike Lloyd/Getty Images). 1977

“The Baja California Pronghorn or Peninsular Pronghorn (Antilocapra americana peninsularis) is a critically endangered pronghorn, endemic to Mexico. The wild population is estimated at 200”. – Wikipedia

Photo: Two rare Peninsular pronghorns, male twins was born at the Los Angeles Zoo on April 24, 2009 in Los Angeles, California. Only 250 antelope-like Peninsular pronghorns are believed to exist in the wild. (Photo by David McNew/Getty Images)

Two brown bear cubs born at Whipsnade Zoo. (Photo by Evening Standard/Getty Images). 1970

An Afghan vendor selling birds to be kept as pets wait for customers in his shop in Kabul on December 11, 2021. (Photo by Ahmad Sahel Arman/AFP Photo)

Ellesse Janda welcomes a spring rainbow at Cresswell in Northumberland, United Kingdom on March 17, 2023. (Photo by Ian Sproat/Picture Exclusive)