There are two different types of coral that you can choose from to add to your coral reef. These types of coral include hard and soft coral. While they are both useful in the coral reef, more people like soft coral because it looks more appealing and unique. Soft corals are most often referred to as corals that have a soft or leathery feel to them. Hard coral, on the other hand, has a hard calcium skeleton. Soft types of coral do not have a 'hard' calcium skeleton but do utilize small amounts of calcium, called spicules, to give themselves some rigidity. Their polyps vary in size and some are retractable whereas others are not.
There are many characteristics that are unique with different types of coral. Soft corals, in general, are very sensitive to their surrounding neighbors and when threatened will retract and produce heavy amounts of mucous for protection. If the mucous is not swept away, it can encourage bacteria or protozoan infections that can cause the death of the coral. For this reason, soft types of coral require medium to slightly high water flow. In addition, leather corals tend to produce a occasional smooth mucous coating (which aids in cleansing themselves) that is shed after one to two weeks and flow helps them 'slough' this coating.
Most types of coral are also sensitive to the amount of light that is presented to them. Their lighting requirements vary from simple fluorescents to strong metal halide. When adding new types of coral to your tank, determine what light intensity the coral was under previously and after an acclimation period slowly increase the intensity. The amount of light presented to the coral will help it to acclimate to their new environment. In the end, having the right conditions for the different types of coral will help you to create the perfect environment for the entire tank.
