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.
The mystery is why we allowed it to happen. The Golden Gate Bridge, with its mythic beauty, easy access, and promise of near-certain death, kills an average of 30 lost souls every year, making it among the most popular suicide sites on Earth. Unattached, middle-aged white men are the most frequent victims.