The San Diego Zoo is a zoo in Balboa Park, San Diego, California housing over 3,700 animals of more than 650 species and subspecies. Its parent organization, San Diego Zoo Global, is the largest zoological membership association in the world, with more than 250,000 member households and 130,000 child memberships, representing more than a half million people. San Diego Zoo pioneered the concept of open-air, cageless exhibits that re-create natural animal habitats. It is one of the few zoos in the world that houses the giant panda.