''Paragoniastrea australensis'', also known as the Lesser star coral, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

stony corals 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 ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Merulinidae Merulinidae is a Family (biology), family of reef-building Scleractinia, stony corals. Characteristics All the genera in this family are colonial, reef-building corals. Skeletal structures are similar to those of Faviidae but are highly fused, w ...

. It occurs in shallow water in the Indo-Pacific region.

Description

Colonies A colony is a territory subject to a form of foreign rule, which rules the territory and its indigenous peoples separated from the foreign rulers, the colonizer, and their '' metropole'' (or "mother country"). This separated rule was often or ...

of ''Paragoniastrea australensis'' can be massive, submassive or encrusting. The

corallite A corallite is the skeletal cup, formed by an individual stony coral polyp, in which the polyp sits and into which it can retract. The cup is composed of aragonite, a crystalline form of calcium carbonate, and is secreted by the polyp. Corallit ...

s are arranged in deep valleys with steep walls. The valleys are meandroid and may be short or long, depending on the habitat in which the coral grows. The

septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

are even and regularly spaced and extend over the valley walls into the next valley. They are finely toothed and have paliform lobes, and the columella are large. This coral is quite variable in colour, most often being some shade of green or brown, with the valley floor often contrasting with the rest of the surface.

Distribution and habitat

This widespread and common species can be found in shallow or clear waters in the Indo-West Pacific (Red Sea, Gulf of Aden, Indian Ocean, Australia, Southeast Asia, Japan and China Sea).

Biology

''Paragoniastrea australensis'' is a zooxanthellate species of coral. It obtains most of its nutritional needs from the

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

s that live within its soft tissues, supplementing this with the

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic organisms caught by the polyps.

Status

This coral is a common species with a wide range and large total population size which makes it more resilient than some other species of coral. The main threats faced by corals are related to the mechanical destruction of their coral reef habitats and

climate change Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...

; these include increasing damage from extreme weather events, rising sea water temperatures and

ocean acidification Ocean acidification is the ongoing decrease in the pH of the Earth's ocean. Between 1950 and 2020, the average pH of the ocean surface fell from approximately 8.15 to 8.05. Carbon dioxide emissions from human activities are the primary cause of ...

. The

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

has assessed the conservation status of this species as being of "

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

". All corals receive protection by being listed on

CITES Appendix II 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 ...

References

External links

Corals of the world
{{Taxonbar, from=Q25382086 Merulinidae Corals described in 1857 Taxobox binomials not recognized by IUCN