The Hooking Hand

A signature hand-form of the Crane and Praying Mantis styles is the hook.

Crane Style hook

Mantis Style hook

These hand-forms are usually used in a defensive manner, to parry, hook, and ensnare an opponent's attack.  However, the tips of the hook, especially in the Crane form, can be used to deliver a powerful "pecking" attack with the tips of all five fingers. 

When the hand is strongly hooked (as in the Mantis Style above), the top of the wrist can be used to deliver a powerful blunt strike.

If the elbows are kept low and close to the body, the hook hand-form alone, without the thumb, can grasp an opponent's wrist with enough power to drag him into a counter-attacking strike or throw.