Photosynthetic gorgonians grow extremely fast in nature and in aquariums. For example the sea fan, Gorgonia ventalina can develop into a 6 in. (15 cm) tall colony within one year after settling, and fragments of the holdfast with live tissue left on the substrate grow into new fans at the same rate (J. Sprung, pers. obs.). Psendoplexaura spp. and Pseudopterogorgia acerosa may grow an inch (2.5 cm) per month per branch, and proliferate new branches that also grow at that rate (J. Sprung, pers. obs. ). However, in a five year study of gorgonians on the southwest coast of Puerto Rico, Yoshioka and Buchanan-Yoshioka (1991) found that colony heights increased on average only 2 cm/year (0.8 - 4.5 cm/yr). The growth rate varies among genera and species, and as colonies approach their maximum size the growth rate measured as height increase is slower than for small colonies. While the height may not increase much in large colonies, branches may proliferate with rapid linear extension rates.
Growth not only pertains to growth of a single specimen but also to growth of the colony as a whole. It has long been established that soft corals are quick colonizers of space and can spread quickly through asexual reproduction and movement. A colony can easily increase its size by budding and pedal laceration, and whole colony movement is also possible (LaBarre and Coll, 1982). When coupled with their allelopathic properties many soft corals can quickly cover large areas of substratum.
Members of the suborder Stolonifera spread via growth of a creeping root-like structure called a stolon. As the stolon spreads over the surface polyps then arise from it. This stolon can take the form of tube-like ribbons (e.g. Clavulavia spp.), sheet-like growths (e.g. Pacbyclavularia spp.) or as sheets connecting tubes of polyps at various levels above the substratum as in Tubipora.
There are a number of different growth forms in the suborder Alcyoniina, which we dealt with in the colony morphology section of this chapter. Growth often involves the enlargement of the colony above the bottom, achieved via increases in the column and capitulum (e.g. Sarcopbtyon); increases in the number of branches and column size (e.g. Alcyonium, Sinularia, Nephtheidae, Nidaliidae); spreading of the coenenchyme over the
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