In Wing Chun there is the dichotomy of the White Crane vs. the Black Snake, this is akin to the White Crane - Black Tiger dichotomy of the ancient Bubishi.
In the Black Tiger as well as the Black Snake, the Blood vessels, organs and circulation are the main target, (White Crane attacks mainly the Nerves and Nerve Systems). Both the Black Tiger and Snake, as they focus on the Blood, take longer to get a dysfunctional affect on an opponent. The differences lay in the methods of attack, with the Tiger using strength to tear, crush or split anatomical targets and the Snake, uses more focused attacks to cause a chain reactionary dysfunction through damage that "poisons" the body, via lymph, bile, etc.
To learn the method, targets and see the affect in real time, the extended films are located at these links: