Blue coral (''Heliopora coerulea'') is a species of colonial

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

. It is the only

octocoral Octocorallia, along with Hexacorallia, is one of the two extant classes of Anthozoa. It comprises over 3,000 species of marine and brackish animals consisting of colonial polyps with 8-fold symmetry, commonly referred informally as "soft cora ...

known to produce a massive skeleton. This skeleton is formed of

aragonite Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation fr ...

, similar to that of

scleractinia Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mo ...

. Individual polyps live in tubes within the skeleton and are connected by a thin layer of tissue over the outside of the skeleton.

Description

The blue coral is the only

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

with a massive skeleton, The unique octocoral species known to create a significant skeleton is coerulea. which is composed of fibrocrystalline

(calcium carbonate). It is a hermatypic

zooxanthellae Zooxanthellae (; zooxanthella) is a colloquial term for single-celled photosynthetic organisms that are able to live in symbiosis with diverse marine invertebrates including corals, jellyfish, demosponges, and nudibranchs. Most known zooxanthell ...

te species with either blue or green-grey polyps located within its skeleton, with each containing eight tentacles. Its colonies are either columnar, plate like or branched. It is a tolerant species and is used in marine aquariums. Iron salts give the skeleton of ''Heliopora coerulea'' its unique color, which allows for easy recognition in fossil outcrops. As such, it is fairly abundant within

paleontology Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure ge ...

, with fossils indicating the species has remained unchanged since the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

. Blue coral has shown a particular resistance to thermal changes in its environment and has actually grown more in warmer temperatures. Image:Heliopora coerulea, Samoa Americana.jpg, Live colony Image:Heliopora coerulea, Samoa.jpg, Close-up on live polyps (notice the 8 arms) Image:Heliopora coerulea (YPM IZ 010737.CN).jpeg, Preserved skeleton, showing the typical color Image:Blue coral - Heliopora coerulea.jpg, ''idem'' Image:Heliopora coerulea (MNHN-IK-2000-348) 001.jpeg, Close-up

Distribution

Despite being common in some areas and having a large range, the blue coral has been given the conservation status of a

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

by the IUCN. Its population is unknown but it is believed to be decreasing in line with the global destruction of coral reefs; it is threatened by aquarium harvesting, bleaching,

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, the acidification of oceans, and climate change. It is found in the eastern and western Indian Ocean, and the eastern central, western central, northwestern, and southwestern Pacific Ocean; its range includes the Great Barrier Reef, Australia, Japan and the

Ryukyu Islands The , also known as the or the , are a chain of Japanese islands that stretch southwest from Kyushu to Geography of Taiwan, Taiwan: the Ryukyu Islands are divided into the Satsunan Islands (Ōsumi Islands, Ōsumi, Tokara Islands, Tokara and A ...

. Its largest colony is believed to be located off

Ishigaki Island , also known as ''Ishigakijima'', is a Japanese island south-west of Okinawa Hontō and the second-largest island of the Yaeyama Island group, behind Iriomote Island. It is located approximately south-west of Okinawa Hontō. It is within t ...

in the

Yaeyama Islands The Yaeyama Islands (八重山列島 ''Yaeyama-rettō'', also 八重山諸島 ''Yaeyama-shotō'', Yaeyama: ''Yaima'', Yonaguni: ''Daama'', Okinawan: ''Yeema'', Northern Ryukyuan: ''Yapema'') are an archipelago in the southwest of Okinawa Pref ...

, southwestern Japan. It is found in reefs with depths below , or reefs exposed to waves, flats, intertidal regions, and sometimes in marginal habitats. The blue coral is listed under Appendix II of

CITES CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

. The world's largest deposit of blue coral is in Shiraho, Japan.Claus, C. A. 2020. Drawing the Sea Near: Satoumi and Coral Reef Conservation in Okinawa. Minneapolis: University of Minnesota Press This deposit however was threatened by the possible development of an airport in 1989. The airport was to be placed over the coral bed and would have resulted in the destruction of these rare coral. Transnational organizations such as the World Wide Fund for Nature stepped in and with public support managed to prevent the construction. The organization also constructed a field research station at the site to further study the corals. The airport was eventually built but at a location where it wouldn't harm the corals. The Fund then attempted to implement their typical procedures of creating protected areas for the coral. However, the prior support from the public disappeared. The residents of Shiraho were opposed to the creation of such areas. Conservationists thus took a different approach. They attempted to further connect the community of Shiraho with the sea, beyond just fishing, to try and inspire a desire to conserve the area. What resulted was the revitalization of sanizu. It is a local celebration where the people give back to the sea gods. The tradition had decreased in prevalence over the years due to a variety of reasons including economic pressure and other local socioeconomic conditions. The Fund was unable to initiate the celebration so instead they provided the tools and resources for it. This led to a large-scale sanizu celebration where both locals and conservationists connected with the sea.

Taxonomy

''Heliopora coerulea'' was described by Pallas in 1766.

References

External links

* {{Taxonbar, from=Q1056942 Helioporidae Corals described in 1766 Taxa named by Peter Simon Pallas