renilla

{{Automatic taxobox

| image = Sea pansy.png

| image_caption = Renilla reniformis

| parent_authority = Gray, 1870

| taxon = Renilla

| authority = Lamarck, 1816

}}The following species are recognized:{{Cite web|url=http://marinespecies.org/aphia.php?p=taxdetails&id=267800|title=WoRMS - World Register of Marine Species - Renilla Lamarck, 1816|website=marinespecies.org|language=en|access-date=2018-04-09}}

• Renilla amethystina Verrill, 1864
• Renilla koellikeri Pfeffer, 1886
• Renilla muelleri Kölliker, 1872
• Renilla musaica Zamponi & Pérez, 1996
• Renilla octodentata Zamponi & Pérez, 1996
• Renilla reniformis (Pallas, 1766)
• Renilla tentaculata Zamponi, Perez & Capitali, 1996

File:Natural history of animals; (1895) (14596299417).jpgRenilla has a distinctive heart shaped colony with a violet or red color.{{Cite web |last=Onishi |first=Takako |title=Renilla koellikeri |url=https://animaldiversity.org/accounts/Renilla_koellikeri/ |access-date=2025-04-14 |website=Animal Diversity Web |language=en}} Pennatulaceans, in the order Pennatulacea, are soft corals in the subclass Octocorallia. But Pennatulaceans have different structures and functions from other octocorals.{{Cite journal |last1=Schoch |first1=Conrad L. |last2=Ciufo |first2=Stacy |last3=Domrachev |first3=Mikhail |last4=Hotton |first4=Carol L. |last5=Kannan |first5=Sivakumar |last6=Khovanskaya |first6=Rogneda |last7=Leipe |first7=Detlef |last8=Mcveigh |first8=Richard |last9=O'Neill |first9=Kathleen |last10=Robbertse |first10=Barbara |last11=Sharma |first11=Shobha |last12=Soussov |first12=Vladimir |last13=Sullivan |first13=John P. |last14=Sun |first14=Lu |last15=Turner |first15=Seán |date=2020-01-01 |title=NCBI Taxonomy: a comprehensive update on curation, resources and tools |journal=Database: The Journal of Biological Databases and Curation |volume=2020 |pages=baaa062 |doi=10.1093/database/baaa062 |issn=1758-0463 |pmc=7408187 |pmid=32761142}} They form one main polyp, oozooid, which anchors itself onto the seabed using a stalk, peduncle, instead of forming a large colony like most soft corals. The top of this oozooid grows into a rachis which is the central structure. From the rachis the Pennatulaceans can grow smaller polyps which have 2 functions; the autozooids which do the feeding, and the siphonozooids which are smaller and aid in movement. The Renilla genus and some other pennatulaceans have structures called polyp leaves. These polyp leaves, which hold many autozooids, are extensions that give Renilla a feather-like appearance. Which is where their common name of Pennatulacea “sea pen” comes from, as these polyp leaves resemble the writing quills. They consist of bilateral symmetry and a soft outer body, the coelenchyme, with three tissue layers: an outer layer called the epidermis, an inner layer called the gastrodermis, and a middle layer called the mesoglea, a jelly-like layer. Inside of a mesoglea, a wide variety of skeletal elements called sclerites are formed.

Sea pansies are geographically worldwide, from the polar seas to the equatorial tropics. And they extend across depths from the shallow shores of intertidal flats to the deep ocean trenches of 6100 meters. Most Renilla often anchor to soft sediment like sand or mud, but some can even anchor to rocky surfaces. Benthic marine environments are where the sea pansies thrive. Some examples include: continental shelves and slopes, shallow coastal areas, coral reefs, deep-sea plains, and hadal zones which are deep ocean trenches. They can live in all of these environments because of the peduncle, which helps them anchor into soft sediment. You can find them in abundance in the Gulf, Atlantic ocean, and the coasts of Southern California.

Renilla are predatory filter feeders.{{Citation |last1=Palomares |first1=Maria L. D. |title=Organizing and disseminating marine biodiversity information: the FishBase and SeaLifeBase story |date=2011-03-03 |work=Ecosystem Approaches to Fisheries |pages=24–46 |url=https://doi.org/10.1017/cbo9780511920943.005 |access-date=2025-04-20 |publisher=Cambridge University Press |isbn=978-0-511-92094-3 |last2=Bailly |first2=Nicolas|doi=10.1017/cbo9780511920943.005 }} Their diet consists of other small animals and larvae. This is accomplished by stinging their prey and capturing them in the mucus they secret on their surface. Which helps pre-digest their prey for swallowing. Once inside, the food is digested through septal filaments and intracellular digestion. Renilla are colonial, but they still exhibit some interesting behaviors; bioluminescence, contraction of their rachis, and polyp withdrawal, which are all thought to be responses of “fear” to external environmental stimuli. Their life cycle consists of  a zygote which develops into planktonic larva. Metamorphosis involves the formation of tentacles, pharynx, and a septa. Then the larval settlement forms at the aboral end of the Renilla. They use sexual and asexual reproductions through the budding of secondary polyps on their surface. They are eaten by the Loggerhead Turtle, Caretta caretta.{{Cite web |title=Isolation and Structure Elucidation of Feeding Deterrent Diterpenoids from the Sea Pansy, Renilla reniformis |url=https://eol.org/pages/46549617 |access-date=2025-04-14 |website=doi.org}} Sea pansies use their calcified sclerites to give their body structure and to defend against predators. Sclerites are formed in the mesoglea and they aid in the composition of the colonies. Research{{Cite journal |last1=Clavico |first1=Etiene E. G. |last2=De Souza |first2=Allan T. |last3=Da Gama |first3=Bernardo A. P. |last4=Pereira |first4=Renato C. |date=October 2007 |title=Antipredator Defense and Phenotypic Plasticity of Sclerites From Renilla muelleri , a Tropical Sea Pansy |url=https://www.journals.uchicago.edu/doi/10.2307/25066629 |journal=The Biological Bulletin |language=en |volume=213 |issue=2 |pages=135–140 |doi=10.2307/25066629 |jstor=25066629 |pmid=17928520 |issn=0006-3185}} shows that they alter the colonies in response to external stimuli in the environment like predation and water motion. The smaller sclerites provide resistance and stiffness, while the larger sclerites contribute to ward off predators. In a research observation, field assays of sea pansies and their sclerites were conducted at three depths. It was concluded that the consumption of sea pansies were greatly reduced, due to the sclerites of the Renilla.

File:Renilla reniformis 6256818.jpgRenilla reniformis are model organisms for studying bioluminescence.{{Cite journal |last1=Loening |first1=Andreas Markus |last2=Fenn |first2=Timothy David |last3=Gambhir |first3=Sanjiv Sam |date=December 2007 |title=Crystal Structures of the Luciferase and Green Fluorescent Protein from Renilla reniformis |journal=Journal of Molecular Biology |language=en |volume=374 |issue=4 |pages=1017–1028 |doi=10.1016/j.jmb.2007.09.078 |pmc=2700051 |pmid=17980388}} They produce a protein called luciferase.{{Cite journal |last1=Anderson |first1=James |last2=Charbonneau |first2=Harry |last3=Cormier |first3=Milton |date=1974-03-01 |title=Mechanism of Calcium Induction of Renilla Bioluminescence. Involvement of a Calcium-Triggered Luciferin Binding Protein |url=https://pubs.acs.org/doi/abs/10.1021/bi00703a602 |journal=Biochemistry |language=en |volume=13 |issue=6 |pages=1195–1200 |doi=10.1021/bi00703a602 |pmid=4149963 |issn=0006-2960}} This protein involves a calcium triggered reaction which breaks down a chemical called coelenterazine in the presence of oxygen to form coelenteramide, carbon dioxide, and light. Because of this, luciferase can be used as a reporter gene in experiments with cell culture and small animal imaging. As for the Renilla themselves, there are plenty of hypothesized reasons why they use bioluminescence. It could serve as a mechanism of defense, an escape response, a way to deter predators, and plenty of other reasons. But no definitive reason has been backed by substantial scientific and statistically significant evidence. Examples of some other bioluminescent animals include fireflies, some bacteria, and sharks.{{Cite journal |last1=Satterthwaite |first1=William H. |last2=Cordoleani |first2=Flora |last3=O'Farrell |first3=Michael R. |last4=Kormos |first4=Brett |last5=Mohr |first5=Michael S. |date=2018-04-16 |title=Central Valley Spring-Run Chinook Salmon and Ocean Fisheries: Data Availability and Management Possibilities |url=https://doi.org/10.15447/sfews.2018v16iss1/art4 |journal=San Francisco Estuary and Watershed Science |volume=16 |issue=1 |doi=10.15447/sfews.2018v16iss1/art4 |issn=1546-2366}}

The phylogeny of sea pansies are still being studied, but there are a few difficulties. The genus Renilla and their order Pennatulacea does not have many distinctive physical traits for analysis.{{Cite journal |last1=Kushida |first1=Yuka |last2=Imahara |first2=Yukimitsu |last3=Wee |first3=Hin Boo |last4=Fernandez-Silva |first4=Iria |last5=Fromont |first5=Jane |last6=Gomez |first6=Oliver |last7=Wilson |first7=Nerida |last8=Kimura |first8=Taeko |last9=Tsuchida |first9=Shinji |last10=Fujiwara |first10=Yoshihiro |last11=Higashiji |first11=Takuo |last12=Nakano |first12=Hiroaki |last13=Kohtsuka |first13=Hisanori |last14=Iguchi |first14=Akira |last15=Reimer |first15=James Davis |date=2022-09-21 |title=Exploring the trends of adaptation and evolution of sclerites with regards to habitat depth in sea pens |url=https://peerj.com/articles/13929 |journal=PeerJ |language=en |volume=10 |pages=e13929 |doi=10.7717/peerj.13929 |doi-access=free |issn=2167-8359|pmc=9508890 }} And with the traits they do have, the sea pansies are really delicate. A lot of preserved samples, as fresh specimens are hard to collect, are  too damaged for DNA analysis. But there are some evolutionary histories which we can take note of. Sea pansies have traits like bilateral symmetry and polyp leaves which are features that were definitely modified and evolved features. And there are a lot of similarities between the Pennatulacea and Ellisellidea.

There was research done as a part of project MEcHa-SBSS where they studied 3 species in the genus Renilla, Renilla muelleri, Renilla musaica, and Renilla tentaculata.{{Cite journal |last1=La Nafie |first1=Yayu A. |last2=de los Santos |first2=Carmen B. |last3=Brun |first3=Fernando G. |last4=Mashoreng |first4=Supriadi |last5=van Katwijk |first5=Marieke M. |last6=Bouma |first6=Tjeerd J. |date=August 2013 |title=Biomechanical response of two fast-growing tropical seagrass species subjected to in situ shading and sediment fertilization |url=https://linkinghub.elsevier.com/retrieve/pii/S0022098113002086 |journal=Journal of Experimental Marine Biology and Ecology |language=en |volume=446 |pages=186–193 |doi=10.1016/j.jembe.2013.05.020|bibcode=2013JEMBE.446..186L |hdl=2066/117299 |hdl-access=free }} They were found in Southern Brazil along the continental shelf between latitudes 28°S and 34°S. These Renilla have a big influence on the ecology of that environment such as type of sediment, water temperature, and salinity. But the populations of the Renilla species are affected by their predators (turtles),  competitors (sand dollars), and human interactions with their habitats. In the study, significant numbers of young Renilla colonies were observed, so they concluded that these interactions with biotic stimuli are not inhibiting reproduction and growth at an alarming rate. Research done by Charbonneau and Cormier studied LBP, a luciferin-binding protein, which has a big part in the bioluminescent process in Renilla reniformis.{{Cite journal |last1=Charbonneau |first1=H. |last2=Cormier |first2=M.J. |date=February 1979 |title=Ca2+-induced bioluminescence in Renilla reniformis. Purification and characterization of a calcium-triggered luciferin-binding protein. |journal=Journal of Biological Chemistry |language=en |volume=254 |issue=3 |pages=769–780 |doi=10.1016/S0021-9258(17)37872-9|doi-access=free }} The LBP is compact with globular shape and a disulfide bond. When calcium binds to LBP, the protein changes shape exposing the coelenterazine, which is a luciferin, to the luciferase enzyme producing light. This reaction is hypothesized to be a response to external stimuli like touch or changes to the environment for defense and/or communication.

{{Reflist}}{{Taxonbar|from1=Q5296120|from2=Q10359435}}

Category:Renillidae

Category:Octocorallia genera

Category:Bioluminescent cnidarians

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