Platygyra daedalea
A common Indo-Pacific stony coral of least concern.
Platygyra daedalea, also called the lesser valley coral, is a colonial stony coral belonging to the family Merulinidae. It is found on shallow-water reefs throughout the Indo-Pacific region and is a common species. The International Union for Conservation of Nature lists its conservation status as "least concern."
This coral typically forms massive dome- or boulder-shaped colonies that can reach a meter or more in diameter, though it may also grow as flattened plates or encrusting sheets. Its polyps live in winding valleys separated by low, often perforated walls. The septa are toothed and protrude, usually with uneven or pointed tips, and a noticeable ridge called the columella runs through the center of each valley. Coloration varies, and the valleys and ridges may contrast. It can be told apart from the rarer Platygyra lamellina by its wider valleys and walls that are more vertical-sided and flat-topped.
Platygyra daedalea has a broad distribution across the Indo-Pacific, from Madagascar, the east African coast, the Red Sea, and the Gulf of Aden to Australia, Indonesia, Japan, and the South China Sea. It inhabits various reef environments, especially back reef slopes, on subtidal rocks down to about 30 meters deep. It is particularly abundant in the Gulf of Thailand and the South China Sea.
At night, the polyps extend to capture floating plankton, but the coral gets most of its nutrition from symbiotic dinoflagellates called zooxanthellae living in its tissues. These algae provide organic carbon and nitrogen through photosynthesis, which is why P. daedalea needs shallow, sunlit waters to thrive. This coral is aggressive and works to keep competitors from overshadowing it. In one study, small colonies of P. daedalea were placed next to similar-sized colonies of the less-aggressive Favites complanata. Some of P. daedalea's tentacles turned into sweeper tentacles up to 90 millimeters long—about fifteen times the normal length—and heavily armed with stinging cells. These tentacles caused extensive damage to the soft tissues of the neighboring F. complanata, exposing the skeleton in places and allowing sponges, algae, and other fouling organisms to grow. Three of the ten attacked corals eventually died.
Quick Facts
- Taxon
- Platygyra daedalea
Facts from the source article.
Lore & Background
Platygyra daedalea usually forms massive dome or boulder-shaped colonies which may be a metre or more in diameter; however, sometimes it forms flattened plates or it may be encrusting. The polyps are situated in meandering valleys with low walls between them which are often perforated. The septa are toothed and protuberant, usually with uneven or pointed tips. There is an obvious ridge, the columella, in the centre of the valley. The colour varies and there may be contrasting valleys and ridges. This coral can be distinguished from the similar but less common Platygyra lamellina by the fact that the valleys are wider and the walls between them have more vertical sides and have flatter tops.
Its range extends from Madagascar, the east coast of Africa, the Red Sea and the Gulf of Aden, to Australia, Indonesia, Japan and the South China Sea. It is present in various reef environments, particularly on back reef slopes, from subtidal rocks down to about 30 metres. It is particularly common in the Gulf of Thailand and South China Sea.
The polyps expand at night to catch planktonic particles floating by. However, this coral obtains most of its nourishment from the dinoflagellates known as zooxanthellae it houses within its tissues. These provide organic carbon and nitrogen, the products of photosynthesis, to their host. To benefit from this symbiotic arrangement, P. daedalea needs to grow in shallow, sunlit environments.
Reader's Guide
Platygyra daedalea is notable for its aggressive competitive behavior. Researchers placed small colonies of this species alongside similar-sized colonies of the less-aggressive Favites complanata. Some of the tentacles of P. daedalea developed into sweeper tentacles which then inflicted damage on the soft tissues of the adjoining F. complanata. These sweeper tentacles were up to 90 millimetres in length, about fifteen times as long as a normal tentacle, and well armed with cnidocytes. The soft tissue damage was extensive, the skeleton was laid bare in places and sponges, algae and other fouling organisms grew on it. Three of the ten corals that were attacked eventually died. This demonstrates the species' capacity to defend its space and outcompete neighboring corals, contributing to its commonness in its range. Its widespread distribution from the east coast of Africa to Japan and the South China Sea, combined with its IUCN status of least concern, underscores its ecological resilience in shallow reef environments.
Did You Know?
- Platygyra daedalea is sometimes known as the lesser valley coral.
- It can form colonies a metre or more in diameter.
- Its sweeper tentacles can reach up to 90 millimetres in length.
- It obtains most of its nourishment from symbiotic zooxanthellae.
More in Brain and Merulinid Corals 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced