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One of the advantages of modular colonial growth is the capability to recover after partial mortality. Tolerance to partial mortality is a known property of some resistant species of plants that respond to mortality with vigorous regrowth or overcompensation. It is not clear whether modular marine invertebrates such as octocorals overcompensate. This study provides evidence that following injury to colonies (by breaking apical dominance), new growth exceeds normal rates of branching, as observed in some plants, in a degree correlated to the original multi-branched network setting (e.g. the number of original branches connected to main stem), in colonies of the Caribbean gorgonian octocoral Pseudopterogorgia bipinnata. This can be explained by the network of communicating vessels and canals inside octocoral colonies, which provide the structure for effective allocation of resources to regenerating parts.

Growth rates of branches of colonies of the gorgonian Pseudopterogorgia elisabethae were monitored for 2 years on a reef at San Salvador Island, Bahamas. Images of 261 colonies were made at 6-month intervals and colony and branch growth analyzed. Branch growth rates differed between colonies and between the time intervals in which the measurements were made. Colonies developed a plumelike morphology through a pattern of branch origination and determinate growth in which branch growth rates were greatest at the time the branch originated and branches seldom grew beyond a length of 8 cm. A small number of branches had greater growth rates, did not stop growing, and were sites for the origination of subsequent "generations" of branches. The rate of branch origination decreased with each generation of branching, and branch growth rates were lower on larger colonies, leading to determinate colony growth. Although colonial invertebrates like P. elisabethae grow through the addition of polyps, branches behave as modules with determinate growth. Colony form and size is generated by the iterative addition of branches.