The sea pansy, ''Renilla reniformis,'' is a species of

colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 au ...

cnidarian Cnidaria () is a phylum under kingdom Animalia containing over 11,000 species of aquatic animals found both in freshwater and marine environments, predominantly the latter. Their distinguishing feature is cnidocytes, specialized cells that th ...

in the family Renillidae, part of an

octocoral Octocorallia (also known as Alcyonaria) is a class of Anthozoa comprising around 3,000 species of water-based organisms formed of colonial polyps with 8-fold symmetry. It includes the blue coral, soft corals, sea pens, and gorgonians (sea fans ...

subclass of

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

that inhabit an expansive range of environments. It is native to warm continental shelf waters of the Western Hemisphere. It is frequently found washed ashore on North East

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...

beaches following northeasterly winds or rough surf conditions. It also can often be found living

intertidal The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

ly completely buried in the sand. Its

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill t ...

is the striped

sea slug Sea slug is a common name for some marine invertebrates with varying levels of resemblance to terrestrial slugs. Most creatures known as sea slugs are gastropods, i.e. they are sea snails (marine gastropod mollusks) that over evolutionary tim ...

, ''

Armina tigrina ''Armina tigrina'' is a species of sea slug, a nudibranch, a marine gastropod mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around ...

''. The sea pansy is a collection of

polyps A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) end i ...

with different forms and functions. A single, giant polyp up to two inches in diameter forms the anchoring stem (peduncle). This peduncle can be distended to better anchor the

colony In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state' ...

in the substrate. The pansy-like body bears many small,

anemone ''Anemone'' () is a genus of flowering plants in the buttercup family Ranunculaceae. Plants of the genus are commonly called windflowers. They are native to the temperate and subtropical regions of all continents except Australia, New Zealand an ...

-like feeding polyps. A cluster of

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

less polyps form an outlet valve that releases water to deflate the colony. If the colony is on a

sand bar In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It ...

at low tide, it usually deflates and becomes covered with a thin film of silty sand. Small white dots between the feeding polyps are polyps that act as pumps to expand the deflated colony. The feeding polyps secrete a sticky mucus to trap tiny organisms suspended in the water. The colony’s rigidity and purple color come from calcium carbonate

spicules Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

throughout the polyp’s tissues. The sea pansy is strikingly

bioluminescent Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

when disturbed because of the interplay between a

luciferase Luciferase is a generic term for the class of oxidative enzymes that produce bioluminescence, and is usually distinguished from a photoprotein. The name was first used by Raphaël Dubois who invented the words '' luciferin'' and ''luciferase'' ...

(

Renilla-luciferin 2-monooxygenase Renilla-luciferin 2-monooxygenase, Renilla luciferase, or RLuc, is a bioluminescent enzyme found in '' Renilla reniformis'', belonging to a group of coelenterazine luciferases. Of this group of enzymes, the luciferase from '' Renilla reniformi ...

) and

green fluorescent protein The green fluorescent protein (GFP) is a protein that exhibits bright green fluorescence when exposed to light in the blue to ultraviolet range. The label ''GFP'' traditionally refers to the protein first isolated from the jellyfish '' Aequore ...

(GFP). Both molecules have recently become extremely important in biology. It also produces secondary metabolites for chemical defence that may make it an interesting source of marine natural products. A draft genome of ''R. reniformis'' was sequenced in 2018, producing a haploid genome size of 172 megabases (Mb). This makes it one of the most small and compact coral genomes discovered to date

References

External links

* *
Bill Frank, Jacksonville, Florida
{{Taxonbar, from=Q288773 Renillidae Bioluminescent cnidarians Corals described in 1766 Taxa named by Peter Simon Pallas