The manipulation of water flow is also important to
determine coral shape. Although choosing the most attractive coral shape is debatable, the most popular corals are
usually branching corals, with a branchlike or arborescent/
bush form. It has been suggested that plasticity in branch
spacing represents a means of acclimatizing to the characteristics of the local flow environment (Sebens et al.1997;
Kaandorp & Kubler 2001; Todd 2008). These studies
showed that particle capture increased with branch spacing
in low flows, but decreased with branch spacing in higher
flows. As space between coral branches affects colony compactness, compact colony forms are generally found in
environmental conditions with large exposure to water
movement, and the growth forms often gradually change
into a more open branching shape when the amount of
water movement decreases (Kaandorpet al.1996). Moreover, thickness of coral branches is higher in high-flow conditions, as observed for the stony symbiotic coral
Pocillopora damicornis (Lesser et al. 1994) and Pocillopora verrucosa(Chindapolet al.2013). Overall, high-density branching can be obtained with high-flow conditions,
whereas low-density branching can be achieved with lowflow conditions. However, it is important to note that
changes in coral shape associated with water flow are slow,
that is, usually take more than 6 months (Todd 2008)