''Millepora platyphylla'' is a species of

fire coral Fire corals (''Millepora'') are a genus of colonial marine organisms that exhibit physical characteristics similar to that of coral. The name coral is somewhat misleading, as fire corals are not true corals but are instead more closely related ...

, a type of hydrocoral, in the family

Milleporidae Fire corals (''Millepora'') are a genus of colonial marine organisms that exhibit physical characteristics similar to that of coral. The name coral is somewhat misleading, as fire corals are not true corals but are instead more closely related ...

. It is also known by the common names blade fire coral and plate fire coral. It forms a calcium carbonate skeleton and has toxic, defensive polyps that sting. It obtains nutrients by consuming plankton and via symbiosis with photosynthetic algae. The species is found from the Red Sea and East Africa to northern Australia and French Polynesia. It plays an important role in reef-building in the Indo-Pacific region. Depending on its environment, it can have a variety of different forms and structures.

Description

From class

Hydrozoa Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specializ ...

, ''Millepora platyphylla'' is not a true coral, distinguishing it from the stony corals and soft corals in class

Anthozoa Anthozoa is a subphylum of marine invertebrates which includes the sea anemones, Scleractinia, stony corals and Alcyonacea, soft corals. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as part of the plank ...

. Like other species of fire coral, it can have diverse growth forms, including branches, fans, plates, blades, or encrusting forms. However, they are generally characterized as plate-like or blade-like, which differentiates them from other species, such as ''

Millepora dichotoma ''Millepora dichotoma'', the net fire coral, is a species of hydrozoan, consisting of a colony of polyps with a calcareous skeleton. Description ''M. dichotoma'' is a colonial hermatypic coral with a calcareous endoskeleton. They form colonie ...

'' and '' Millepora exaesa''. The morphologies of these corals vary based on the habitats they inhabit. While encrusting forms are better able to resist wave activity, exposed sheet tree forms coupled with the action of breaking waves may facilitate the coral's reproduction through fragmentation. Similar to other reef-building corals, ''M. platyphylla'' constitutes colonies and possesses stinging cells called

nematocysts A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this c ...

. The presence of these stinging cells is what gives these fire corals their name, as contact with them leads to a burning sensation in humans. The coral has two types of polyps: gastrozooids for feeding and dactylozooids for defense. The structures of the polyps are specialized for their function. The gastrozooid consists of a circular perimeter of short tentacles around an oral cavity, while the dactylozooid lacks the cavity and instead has longer tentacles used for defensive purposes. These polyps occupy gastropores and dactylopores, respectively, arranged as cyclosystems. They have

gonophore A gonophore is a reproductive organ in Hydrozoa that produces gametes. It is a sporosac, a medusa or any intermediate stage. The name is derived from the Greek words (, that which produces seed) and (, -bearing). Gonophores are borne on branch ...

s for reproductive organs. The size of ''M. platyphylla'' colonies can be highly variable, though they often have diameters ranging from 200 to 300 centimeters and heights up to 200 centimeters. The corals can exhibit a yellow-green color or a light-brown color, though their tips may be white.

Distribution

''Millepora platyphylla'' has a wide geographic range, especially compared with those of other species like ''Millepora latifolia'' and '' Millepora tenera''. It is commonly found in the Indo-Pacific, which encompasses the Red Sea and French Polynesia. Researchers have studied the species in Indonesia, Egypt, and Moorea, French Polynesia. For a period of time, it was presumed that the species no longer existed in the Eastern Pacific due to bleaching events. However, researchers have confirmed that its range now extends back to that location. The species is found in the shallows of the reef crest, typically below 5 meters in depth, but they may also be found there at depths up to 10 meters. They can be found at the surf zone and spur and groove zone at depths up to 10 meters. They experience strong wave action around these depths.

Biology

''Millepora platyphylla'' obtains energy from a combination of zooplankton predation and symbiosis with photosynthetic

zooxanthellae Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus ''Sy ...

. The mouths of the gastrozooids open and close in response to the presence of food. The hairs of the fire coral facilitate the feeding process. Zooxanthellae live within the coral tissue, providing it with nutrients via photosynthesis and in turn receiving adequate shelter and better access to sunlight. Reproduction occurs sexually or asexually. As a species that exhibits

gonochorism In biology, gonochorism is a sexual system where there are only two Sex, sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochor ...

, ''Millepora platyphylla'' releases medusoid reproductive buds, which in turn release gametes into the water for external fertilization. The resulting planula larvae calcify into a polyp after 1 day. Asexual reproduction occurs through the process of fragmentation. While adults are sessile, planula larvae have the ability to swim or crawl before settling on substrate and undergoing metamorphoses. Fragments of existing colonies can disperse in turbulent waters, colonizing nearby reef areas.

References

{{Taxonbar, from=Q2429205 Milleporidae Corals described in 1834 Taxa named by Christian Gottfried Ehrenberg Taxa named by Wilhelm Hemprich