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.
Unfortunately, the U.S. Merchant Marine has no official historians and researchers, and statistics for WWII vary: 1  Mariners killed at sea direct result of enemy action or as POW on American flag ships Coast Guard: 5,662. 2  Mariners killed at sea from war causes, compiled by Captain Arthur Moore: 6,847.