Excess of 4,000 different animals and around 500 animal species, including African elephants, Amur tigers, Grant`s zebras, Masai giraffes, monkeys, polar bears, ring-tailed lemurs, sea lions and sea otters, along with birds, reptiles and invertebrates galore. Pittsburgh Zoo`s outstanding PPG Aquarium opened as recently as the year 2000 and features state-of-the-art tanks and aquariums, with sharks and a marine environment within its Ocean Tank, a Stingray tunnel, and a flooded Amazon rainforest exhibit.