Question

Hard corals secrete an _____ of calcium carbonate around themselves. These animals can form coral reefs in shallow waters in the tropics, because they contain symbiotic photosynthetic _____.

Answer 1

Hard corals create an exoskeleton of calcium carbonate that forms coral reefs. They rely on symbiotic unicellular algae for nutrition, which requires sunlight for photosynthesis, necessitating their presence in shallow waters. This relationship is vital for coral survival in nutrient-poor tropical waters.

Step-by-step explanation:

Hard corals secrete an exoskeleton of calcium carbonate around themselves. These animals can form coral reefs in shallow waters in the tropics because they contain symbiotic photosynthetic unicellular algae known as zooxanthellae.

Corals exist as colonies of polyps in the phylum Cnidaria. They catch plankton with their tentacles for nourishment and rely heavily on their symbiotic relationship with algae. The algae require sunlight to conduct photosynthesis, making it essential for corals to reside in the shallow, sunlit waters of the tropics. Over time, the secreted calcium carbonate builds up, forming the reef structures that protect coastal regions and support high biodiversity.

Photosynthetic algae, such as zooxanthellae within the coral polyps, provide essential nutrition and energy through their photosynthetic activities. This mutualistic relationship allows corals to thrive in nutrient-poor tropical waters. However, corals are sensitive to changes in their environment and are at risk of coral bleaching if their symbiotic algae are lost.