A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. [1]

Oct 15, 2024 · A coral reef is a term used to describe the collective structure of hard corals that help shape a coral reef ecosystem. “A coral reef is a reef whose main structure is made by …

Sep 25, 2025 · Coral reefs are some of the most diverse ecosystems in the world. Coral polyps, the animals primarily responsible for building reefs, can take many forms: large reef building …

Nov 27, 2025 · Coral reef, ridge or hummock formed in shallow ocean areas by algae and the calcareous skeletons of coral polyps and other coelenterates. A coral reef may grow into a …

Feb 5, 2025 · Coral reefs provide habitat for a large variety of marine life, including various sponges, oysters, clams, crabs, sea stars, sea urchins, and many species of fish. Coral reefs …

Coral reefs are the most diverse of all marine ecosystems. They teem with life, with perhaps one-quarter of all ocean species depending on reefs for food and shelter. This is a remarkable …

Coral reefs are made up of colonies of hundreds to thousands of tiny individual corals, called polyps. These marine invertebrate animals have hard exoskeletons made of calcium …

Discover how coral reefs work, why they’re vital to marine life and how tiny coral polyps build vast underwater ecosystems. Learn about symbiosis, reef biodiversity and the powerful connection …

Jun 16, 2025 · What is a Coral Reef? A coral reef is a vibrant, underwater ecosystem built from the accumulated calcium carbonate skeletons secreted by tiny animals called coral polyps.

Corals are extremely ancient animals that appeared as solitary polyps more than 400 million years ago, and evolved into modern reef-building forms over the last 25 million years. Coral reefs are …