The lobe coral is a common reef-building coral that grows very large and builds large coral reefs throughout its range. This species is one of relatively few that live throughout the tropics, across the entire Indo-Pacific Ocean basin, from the Red Sea to the tropical eastern Pacific, where it is one of the most important reef-building species.
This species forms large structures that can reach several meters across. Though they appear to be very large, only the outer few millimeters represent living tissue, while the rest is a calcium carbonate skeleton. Lobe coral structures only grow a few centimeters each year and may be hundreds of years old. Each structure is actually a colony of several genetically identical animals living together. In some areas, several colonies grow together to form a nearly continuous stretch of lobe corals that may be tens of meters (or more) long. Unlike many species of corals, lobe corals are either male or female, not both. They reproduce via broadcast spawning, where several individuals release their eggs or sperm into the water column at the same time. This method increases the likelihood that eggs become fertilized and reduces the danger from egg predators near the reef surface. Within a few days after the eggs hatch, larvae settle onto the reef surface and begin to form new colonies.
Like most shallow-water corals, lobe corals have symbiotic algae living within their cells, providing the corals with excess energy that they make via photosynthesis (the use of sunlight to convert carbon dioxide into food/energy). Nearly all species of shallow-water corals and several other groups of reef invertebrates have symbiotic relationships with these algae, so it is important that they live in clear, shallow water. Lobe corals also filter feed and eat small zooplankton and other prey from the water column. This food provides them with additional energy and provides their symbiotic algae with the necessary nutrients to continue to generate food.
Though lobe corals are fairly common and live across a very large geographic range, they are depleted in some areas as a result of a combination of local stressors and climate change. Scientists believe that this species is near threatened with extinction.
Engage Youth with Sailors for the Sea
Oceana joined forces with Sailors for the Sea, an ocean conservation organization dedicated to educating and engaging the world’s boating community. Sailors for the Sea developed the KELP (Kids Environmental Lesson Plans) program to create the next generation of ocean stewards. Click here or below to download hands-on marine science activities for kids.