Favites complanata
A near-threatened stony coral of the Indo-Pacific region.
Favites complanata, commonly called the larger star coral, is a stony coral belonging to the family Merulinidae. Its range covers the Indo-Pacific, from the Red Sea and Indian Ocean across to the western and central Pacific. This coral is not common, and its numbers appear to be dropping; the IUCN lists it as near threatened.
Colonies of this species grow into solid, dome-shaped mounds. The corallites—the cups that house the polyps—are large, somewhat angular, and separated by thick, rounded walls. Each cup measures between 8 and 12 millimeters across. Inside, the septa (stony ridges) are arranged in two whorls, with four or five teeth per ridge. The first whorl has distinct paliform lobes, and the central columella is large. The ridges continue between corallites as costae, often forming three-pointed stars where three walls meet. The coral is typically a dull brown, though the polyps’ oral discs may be green or grey.
This species lives across the western and central Indo-Pacific, from Madagascar, the Seychelles, and the Red Sea to India, the Maldives, Australia, Japan, and the East China Sea. It occupies various reef habitats down to about 30 meters deep.
The polyps extend their tentacles to capture plankton, but most of the coral’s nutrition comes from symbiotic zooxanthellae living in its tissues. These single-celled dinoflagellates produce organic compounds through photosynthesis. When stressed—for instance, by high water temperatures above 30°C—the coral may expel its zooxanthellae, turning white in a process known as bleaching.
Quick Facts
- Taxon
- Favites complanata
Facts from the source article.
Lore & Background
Favites complanata forms colonies as solid domes or mounds. Its corallites are large and somewhat angular, with thick, rounded walls. The calyces measure 8 to 12 millimetres in diameter. The septa are arranged in two whorls, each with four or five teeth, and the paliform lobes are distinct on the first whorl. The columella at the centre of each corallite is large. Costae continue between corallites and often form three-pointed stars where three corallite walls meet. The coral is usually a dull brown colour, with oral discs of the polyps sometimes being a contrasting green or grey.
Its range extends from Madagascar, the Seychelles and the Red Sea to India, the Maldives, Australia, Japan and the East China Sea. It inhabits various reef habitats at depths down to about 30 metres. The polyps expand tentacles to catch plankton, but much of its nutrition comes from symbiotic zooxanthellae within its tissues. When stressed by high temperatures above 30 °C, the coral may expel these algae and become bleached white.
Reader's Guide
Favites complanata is notable as a near-threatened species of stony coral within the family Merulinidae. Its conservation status, assessed by the International Union for Conservation of Nature, reflects a decreasing abundance across its Indo-Pacific range. The species is ecologically significant as a reef-building coral that relies on symbiotic zooxanthellae for most of its nutritional needs, making it vulnerable to bleaching events triggered by water temperatures above 30 °C. Its distribution spans from the Red Sea and Indian Ocean to the western and central Pacific, including diverse reef habitats down to about 30 metres depth. The coral's physical characteristics—large angular corallites, two-whorled septa with teeth, distinct paliform lobes, and three-pointed star formations at wall junctions—aid in field identification. Its dull brown colour with occasional green or grey oral discs further distinguishes it. As an uncommon species showing signs of decline, Favites complanata serves as an indicator of reef health and thermal stress in the Indo-Pacific region.
Did You Know?
- Favites complanata is sometimes called the larger star coral.
- Its corallite walls often form three-pointed stars where three corallites meet.
- Bleaching occurs in this species when water temperature rises above 30 °C (86 °F).
- The International Union for Conservation of Nature lists it as near threatened.
Frequently Asked Questions
What is Favites complanata?
Favites complanata, widely known as the larger star coral, is a stony (scleractinian) coral species classified within the family Merulinidae. It is a relatively uncommon Indo-Pacific reef builder that forms solid, dome-shaped colony mounds.
What do Favites complanata corallites look like?
The polyp cups (corallites) are notably large—roughly 8 to 12 millimetres across—with a somewhat angular shape set apart by thick, rounded skeletal walls. Inside each cup, stony ridges called septa line the interior, giving the corallite a distinctive internal architecture.
Where does Favites complanata live and how deep can it be found?
Its natural range stretches from the Red Sea and Indian Ocean across to the western and central Pacific. Populations have been recorded down to approximately 30 metres (about 100 feet) on reef slopes and flats.
What is the conservation status of Favites complanata?
The IUCN currently lists the species as Near Threatened, reflecting a noticeable decline in observed numbers across its Indo-Pacific range. It is not yet classified as threatened, but its rarity and downward trend make it a species of growing concern for reef managers.
What environmental factor most directly threatens Favites complanata?
Sustained water temperatures above roughly 30 °C (86 °F) push the coral past its bleaching threshold, causing it to expel its symbiotic algae and risk mortality. Combined with its already low population density, this thermal sensitivity makes the species especially vulnerable to climate-driven warming events.
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