The industry of coral propagation seems to be reaching a state of enlightenment where the knowledge of fundamental procedures for the simple division of reef invertebrates is becoming time-tested and even commonplace. It is wonderful to see so many corals in captivity that once were thought to be impossible to keep alive not so long ago now routinely pruned like shrubbery. In gross terms, the captive propagation of coral may be categorized by the action of the event: induced passively, naturally occurring or imposed. Passive induction would include strategies of division that neither result in the immediate production of a free-living clone, nor will they necessarily occur unassisted. Rather, such techniques are methods for spurring budding through fission. Some examples of the induced passive division include slicing or notching the periphery of the stolon mat of hardy soft corals such as Star Polyp (Pachyclavularia) or nicking the exposed and illuminated stalk of a leaning (or forcibly tilted) stalk of an Alcyoniid, which often spurs the budding growth of beautiful multi-stalked colonies. Natural strategies of captive coral propagation occur with various manipulations and/or imitations of natural dynamics of the reef environment and are being seen with increasing regularity. They are indeed some of the most interesting events to behold and the subject of another discussion altogether. Indeed, harnessed natural reproductive events like planulae harvest are the future of our trade.
For more than a few years, however, the most common coral propagation technique has been the imposed fragmentation of soft and stony reef corals through cutting, breaking or sawing. By definition, these are deliberate actions taken to asexually propagate a coral and produce divisions that are free-living clones of the parent/donor. They are the fastest and most popular way to farm corals to date, and they are the foundation of our cottage industry. Indeed, imposed fragmentary techniques will likely dominate coral farming until larval rearing techniques are refined.
Header photo found at http://www.coralvita.co/coral-farming/