The word tantra had a special meaning as applied to the temples of Kerala. It is both a science and an art. It deals with structural and functional aspects of the temples and images, the dedication and consecration of the idol. The expert in tantra is called Tantri.
Puzhakkara Chennas Namboodiri is the hereditary Tantri of Guruvayur. The Tantra Samuchaya according to which temples rites and rituals are performed in most of the temples in Kerala was written by Chennas Narayanan Namboodiri, born in 1427.
When Punnathur chief submitted to the Zamorin, Chennas also joined the Zamorins' party in the Koorumatsaram and its senior most member became the Zamorins' spiritual adviser and supervisor of the temples in the empire. The Tantri lives in the tantrimadam near the temple. He offers Utsava bali (offerings to the celestial attendants) on Utsava days and takes part in all special worships during the Mandalam.
Derived from the Malayalam word 'oothuka'- to recite the Vedas. The othikkan is a person who chants as well as teaches the Veda. From the ancient times, Guruvayur has been having four othikkans, known from their house names, as Pazhayam, Munnoolam, Pottakuzhi and Kakkad .They assist the Melsanthi by performing the Pantheeradi pooja (the worship when the sun's shadow measures 12 feet). The Othikkans officiate for the Tantri during the utsavam and other festivals and also when the tantri is not available due to sickness or so.
The Melsanthi (Chief Priest) is appointed for six months at a time. In Guruvayur, the Melsanthi has to observe strict brahmacharya and has to live within the temple premises. He is now appointed by the Managing Committee. Before taking the charge of the office, he has to undergo a fortnight's probation under the Tantri and Othikkans. The Tantri imparts to him, the Dhyanasloka, the litany and deity worshipped forms and schools him in 'Moolamantra' or the secret syllables associated with deity. The Othikkans instruct him in ancient practices of the temple.
The Keezhsanthis are the subordinate temple priests. The Melsanthi is assisted by two Keezhsanthis. They prepare everything for the daily worship and attend to the daily chores such as bringing water, making sandal paste, cooking the nivedyam (offerings for the Lord). They also distribute the prasadam such as worshipped flowers, sandal paste and the idol anointed oil.
He takes the Utsava vigraha on the elephant's back for seevelis. They perform the annual Chempakasseri and Desavarma sradham on behalf of the Lord. They cannot however act for the Melsanthi, neither can the Keezhsanthis touch the Moolavigraha ( the main idol). Since the return of the vigraha of the Lord , the duties of the Keezhsanthis are being performed by fourteen Namboodiri illams of Karisseri (Puzhavy) by turn, two illams (houses) performing the various services month by month.