what are coral polyps

Coral polyps are tiny animals that are related to anemones and jellyfish. They can live individually or in large colonies that comprise a coral reef. Almost all corals are colonial organisms, meaning they are composed of hundreds to hundreds of thousands of individual animals called polyps. Each polyp has a saclike body and a mouth that is encircled by stinging tentacles. The polyp uses calcium carbonate from seawater to build a hard, cup-shaped skeleton that protects the soft, delicate body of the polyp. Most corals are made up of hundreds of thousands of individual polyps, and many stony coral polyps range in size from one to three millimeters in diameter. The walls surrounding the calyx are called the theca, and the coenosarc is a thin band of living tissue that connects individual polyps to one another and helps make it a colonial organism.