Final answer:
corals reefs are formed by the calcium carbonate skeletons of tiny marine animals called corals, not rocks. These corals are living organisms that create large structures known as coral reefs, which are vital to marine biodiversity.
Step-by-step explanation:
The statement that coral reefs are made of tiny animals is true. Coral reefs are indeed formed by the calcium carbonate skeletons of tiny marine invertebrates known as corals, belonging to the phylum Cnidaria. These organisms are not rocks but are living creatures that form colonies composed of many individual coral polyps.
Corals build their skeletons from calcium carbonate, which contributes to the structure of coral reefs over time. Although some corals may appear rock-like or even plant-like, they are, in fact, alive and function as animal organisms. They capture their food from the water, consuming tiny organisms to obtain energy. Additionally, corals engage in a symbiotic relationship with algae, which also assists them in obtaining nutrients, especially in waters where sustenance is not abundantly available.
Coral reefs are crucial ecosystems, providing habitat for a diverse array of marine species including approximately one-third of the world's marine fish species. These sensitive environments are at risk due to factors such as unsustainable harvesting for the pet trade and environmental changes, underscoring the importance of conservation efforts to preserve these rich and vital biological communities.