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In this paper, we investigated the age distribu-9 tion and dynamics of polyps in the slow-growing and long-10 lived gorgonian Corallium rubrum (the Mediterranean red 11 coral), applying an a posteriori demographic approach by 12 considering each colony as a population of polyps. In the 13 Mediterranean red coral, new polyps emerge from the 14 coenenchyme in different regions of the colony and their 15 budding rate depends on the age of branches. The age of 16 polyps, branches and colonies were estimated using the 17 organic-matter-staining dating method on thin sections of 18 the colony skeleton. The median age and maximum life 19 span of polyps were 4 and 12 years suggesting the presence 20 of senescence processes: thus a colony renews several 21 times its polyps during life cycle. Polyps were divided into 22 annual age classes, and their mortality rates calculated. The 23 polyp age distribution was then used to construct a mor-24 tality table and an algebraic transition matrix based on the 25 age at death of 234 polyps. Finally, the polyp budding rate 26 of a young, unbranched colony was calculated, and polyp 27 temporal dynamics simulated. These findings represent the first steps for developing demographic models able to describe polyp dynamics of old and highly branched colonies.