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.
Story highlights. 1  Two World War II shipwrecks lie two miles apart in the Gulf of Mexico. 2  One is a German U-boat that sank an American steamer. 3  Nazis sank about 50 American ships in the Gulf during the war.  Exploration Vessel Nautilus conducted dives in July to learn more about 1942 incident.