AppearancePlatygyra sinensis is a widespread coral that typically forms large, domed colonies up to a metre or more in diameter. The diameter of its colonies often decreases with increasing water depth, and the colonies may sometimes also be flat.
Platygyra sinensis is often known as a ‘brain coral’ due to the meandering, brain-like pattern of ridges, or walls, across its surface. In this species, the walls are relatively thin and are usually separated by short ‘valleys’, although longer, meandering valleys do also sometimes occur. The colonies of Platygyra sinensis display a wide range of colours, with some being dull and others quite bright.
As in all corals, the colonies of Platygyra sinensis consist of numerous, anemone-like animals known as polyps, which have a sac-like body and a central ‘mouth’, surrounded by tentacles. The polyps secrete a hard skeleton, with the skeleton of an individual polyp being known as a ‘corallite’. In Platygyra sinensis, each corallite has internal projections, known as septa, which in this species are thin, evenly spaced, and have tooth-like indentations along their edges.
The corallites of Platygyra sinensis share common walls, and the mouths of the polyps are aligned along the colony’s valleys, with most valleys only having one mouth, but more elongated valleys sometimes having several.
DistributionPlatygyra sinensis is widespread in the Indian Ocean, including the Red Sea and Arabian Gulf, as well as in the western and central Pacific Ocean.
HabitatMost reef environments, especially back reef margins. Usually found at depths of up to 30 metres, Platygyra sinensis occurs in most types of reef habitat. However, it particularly favours the margins of back reefs, which are the more sheltered, shallower parts of the reef closest to the shore
ReproductionLike other corals, Platygyra sinensis is able to reproduce asexually by a process known as ‘budding’, in which a polyp divides into two or more new polyps. Corals also reproduce sexually, usually by releasing large numbers of eggs and sperm into the water column, where the eggs are fertilised and develop into larvae. The larvae eventually settle onto the substrate and develop into polyps, starting new colonies.
Relatively little information is available on reproduction in Platygyra sinensis, but it is reported to have pink eggs and is hermaphroditic, with each polyp producing both eggs and sperm. In the Great Barrier Reef, off the coast of Australia, Platygyra sinensis has been recorded taking part in mass spawning events with other coral species, with most colonies releasing their eggs and sperm over a number of consecutive nights. Spawning in this region has been recorded in spring, between October and November, and usually occurs after a full moon. Platygyra sinensis has been found to spawn around three to four hours after sunset
FoodPlatygyra sinensis is a zooxanthellate coral, meaning that it obtains most of its nutrients from symbiotic algae, known as zooxanthellae, which live within its tissues. The zooxanthellae provide the coral with nutrients through photosynthesis, but this restricts corals such as Platygyra sinensis to living in relatively clear, warm, shallow waters where photosynthesis can take place. In return for nutrients, the coral provides the zooxanthellae with a safe, stable environment in which to live.
In addition to receiving nutrients in this way, Platygyra sinensis is able to supplement its diet with tiny zooplankton, which it catches using stinging cells on its tentacles. The tentacles of this species are usually only extended for feeding at night, and are retracted during the day.
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