welcome to another episode of marine science facts today we will explore the different types of coral reefs and their formation coral reefs are formed through the accumulation and growth of coral polyps tiny marine organisms that belong to the phylum night area different types of coral reefs form in varying environmental conditions here are the three main types of coral reefs and how they form fringing reefs fringing reefs are the most common type and form along the coastline of land masses or Islands they develop close to the shore extending directly from the coastline into the shallow Coastal Waters fringing reefs often grow on volcanic or rocky substrates initially Coral larva settle on hard surfaces such as rocks or old Coral skeletons over time as more Coral polyps attach and build their skeletons The Reef structure grows vertically gradually forming a fringing reef parallel to the coastline barrier reefs barrier reefs are similar to fringing reefs but are separated from the mainland by a lagoon they develop farther offshore and usually run parallel to the coastline barrier reefs are often found in areas with deep water close to the coast they form when a fringing reef grows and extends further away from the shore due to a combination of factors such as changes in sea level subsidence of the land or tectonic activity as the fringing reef continues to grow and build upwards it eventually forms a barrier reef atolls atolls are circular or horseshoe-shaped coral reefs that surround a central Lagoon they are typically found in open ocean areas and often occur as remnants of volcanic islands that have subsided beneath the water surface at all formation starts with the establishment of a fringing reef around a volcanic island over time the volcanic island subsides either due to tectonic activity or natural processes while the coral continues to grow upwards as the island sinks the coral reef forms a ring-shaped structure enclosing a lagoon resulting in the formation of an atoll it's important to note that all coral reefs rely on the symbiotic relationship between coral polyps and photosynthetic algae called zoazantheli the zoazanthelli provide corals with nutrients through photosynthesis while the corals offer the algae a protected environment the availability of sunlight warm water temperatures and Clear Water free from sedimentation are crucial for Coral growth and reef development I hope you enjoyed today's video if you want to learn more interesting facts about the Marine environments don't forget to subscribe and hit that notification Bell feel free to leave a comment for any video recommendations