Final answer:
The coral reef, occupying less than one percent of ocean space while supporting 25% of all marine organisms, is found in the photic zone of shallow ocean ecosystems and represents a critical habitat for marine biodiversity.
Step-by-step explanation:
The area where an estimated 25% of all marine organisms live, which comprises less than one percent of the available ocean space, is referred to as the coral reef. Coral reefs are found in the photic zone of the ocean, which is characterized by enough sunlight for photosynthesis to occur. These reefs are located within 30° north and south of the equator and are some of the most diverse ecosystems on Earth. Coral reefs are particularly prevalent in shallow ocean ecosystems, housing around 4,000 species of marine fish. The intricate relationship between corals and the photosynthetic algae that live within their structures is essential for the survival of these ecosystems, which are often found at depths of approximately 60 meters (or about 200 feet). As such, coral reefs represent a critical habitat for a myriad of aquatic life forms, despite their relatively small spatial footprint in the vast oceans.