The Berlin Zoological Garden () is the oldest surviving and best-known zoo in Germany. Opened in 1844, it covers and is located in Berlin's Tiergarten. With about 1,380 different species and over 20,200 animals, the zoo presents one of the most comprehensive collections of species in the world. The zoo and its aquarium had more than 3.5 million visitors in 2017. It is the most-visited zoo in Europe and one of the most popular worldwide. Regular animal feedings are among its most famous attractions. Globally known animals like Knut, the polar bear, and Bao Bao, the giant panda have contributed to the zoo's public image. The zoo collaborates with many universities, research institutes, and other zoos around the world. It maintains and promotes European breeding programmes, helps safeguard several endangered species, and participates in several species reintroduction programs. History Opened on 1 August 1844, the Zoologischer Garten Berlin was the second zoo in Germany after the short-lived "Thiergarten" in Hamburg-Horn. The aquarium opened in 1913. The first animals were donated by Frederick William IV, King of Prussia, from the menagerie at Pfaueninsel island and pheasantry of the Tiergarten. The nearby U-Bahn station was opened in 1882. Third Reich In 1938, the Berlin Zoo got rid of Jewish board members and forced Jewish shareholders to sell their stocks at a loss, before re-selling the stocks in an effort to "Aryanize" the institution. Starting in 1939, Jews were also prevented from visiting the zoo. Zoo director Lutz Heck was named chief of the Oberste Naturschütz Behörde im Reichsforstamt (highest nature preservation agency in the state department of forestry) by his friend Hermann Göring in the summer of 1938 and in this capacity he was the senior responsible person for the entire nature management. World War II During World War II, the zoo area was hit by Allied bombs for the first time on 8 September 1941. Most damage was done during the bombardments on 22 and 23 November 1943. In less than 15 minutes, 30% of the zoo population was killed on the first day, and on the second day the aquarium building was completely destroyed by a direct hit. Of the eight elephants, only one survived, the bull Siam, and 2-year-old hippo bull Knautschke was saved from the gunfire in his animal house. Most damage was done during the Battle of Berlin: from 22 April 1945 onwards, the zoo was under