Instinctive behavior occurs when an animal has a particular internal state while it is in the presence of a specific external stimulation called a releaser or a sign stimulus.
How many ships did the U-boats sink? During the war the U-boats sank about 2,779 ships for a total of 14.1 million tons GRT. This figure is roughly 70% of all allied shipping losses in all theatres of the war and to all hostile action. The most successful year was 1942 when over 6 million tons of shipping were sunk in the Atlantic.
There are only four of them left--the Missouri, Wisconsin, Iowa and New Jersey--all launched during World War II, when the Navy had a total of 23 battleships. These last four survivors have in recent years been berthed at either Philadelphia or Bremerton, Wash., as part of the inactive or mothball fleet held in readiness for the next war.