Final answer:
Coral reefs are found in shallow tropical waters, typically within 30 degrees of the equator, where they rely on sunlight and a symbiotic relationship with algae for nutrients.
Step-by-step explanation:
Coral reefs are typically found in shallow tropical waters within the photic zone of the ocean.
Coral reefs are ocean ridges formed by marine invertebrates, mainly consisting of cnidarians and mollusks, which thrive in warm, shallow marine areas, usually within 30° north and south of the equator. One of the most famous examples is the Great Barrier Reef, located off the coast of Australia. These biological structures require sunlight, hence they are typically found at depths of around 60 meters (about 200 feet) or less, in waters that are nutrient-poor. Corals engage in a symbiotic relationship with photosynthetic unicellular algae, which provides them with essential nutrients. This mutualistic relationship is crucial for their survival and the development of large coral structures. Although there are some deep-sea corals, they do not form the reef systems associated with tropical shallow waters.