The Coral Reef uses water to drink, eat, keeping clean, playing, and others. I am going to try to list at least one example in each category.
Category 1: Drinking and eating- Corals also eat by catching tiny floating animals called zoo-plankton. At night, coral polyps come out of their skeletons to feed, stretching their long, stinging tentacles to capture critters that are floating by.
Category 2: Keeping Clean- They don't clean themselves.
Category 3: Swimming- They swim freely in the open ocean amidst other plankton. Only later do they find a suitable place to settle down and get on with the adult business of reef construction.
Category 4: Hunting or Playing- Coral don't hunt. They just eat. Coral play by swaying in the water.
Category 5: Going to the Bathroom- I think the coral just go to the bathroom no matter where they are.