In Hasthalakshanadeepika, the classical text on the dances of Kerala, there are 24 basic mudras or hand signs mentioned. These Mudras are used in the classical dance dramas of Kerala, like Kathakali, Kutiyattam, Nangiarkoothu, Mohiniyattam and Ottanthullal.

Bending the index finger like a hook, folding the other three fingers into the palm and touching the middle finger with tip of the thumb is Shukathunda. 

Shukathunda using both palms indicates :
Bird and elephant hook. Though in practice, the eyebrow and certainty are also indicated in Shukathunda mode. According to the Hastalakshanadeepika, the eyebrow should be in the Suchikaamukha mode and while certainty in the Shukathunda mode.