Animal Kings: Ants, like these workers carrying eggs to a plant's leaf after rain flooded their nest, have a combined biomass estimated in the billions of tons. Gurinder Osan/AP hide caption itoggle caption Gurinder Osan/AP The Two-Way Along With Humans, Who Else Is In The 7 Billion Club? November 3, 2011 There are now 7 billion people, according to the U.N.'s population division. That prompts a question: Who else is in the 7 Billion Club? To learn which other animals had reached that plateau, we asked wildlife experts — who said it's a tough call.