Coral Reef

ocean · ecosystem · colorful

Built by tiny animals. Coral reefs are made by little creatures called coral polyps. Even though each one is tiny, millions team up to build a giant reef.

Natural stone builders. Polyps make hard skeletons out of calcium carbonate, the same stuff found in seashells and chalk. Over time these skeletons stack up into a reef.

Underwater cities. Reefs are packed with life, giving food and shelter to fish, sea turtles, crabs and countless other ocean animals.

Stony coral champs. Most reefs are built from stony corals, whose polyps cluster together in big groups to form the reef's solid structure.