Both hard and soft corals have one most efficient and unique nutritional modes in the oceans.  They are successful and voracious predators.  They use different methods to capture their prey.  The coral's tentacles that capture the prey, are large and very poisonous.  The most characteristic of the coral's feeding habit is that they retract their tentacles during the day and feed only at night.  This is because the zooplakton on which they feed is more abundant during the night.  During the day  the zooxanthellae that harbor within their cells can use sunlight to cover water and carbon into food.  The elements that they lack they receive from the waste products of the polyp.  since the corals feed during the night they are carnivorous specialists.  Because of the zooxanthellae they do not need the sunlight to feed and therefore the two become and efficient feeding system with extreme efficiency.