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.
Two World War II shipwrecks lie two miles apart in the Gulf of Mexico. One is a German U-boat that sank an American steamer. 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.