View source for Biology:Halimeda tuna

{{Short description|Species of alga (seaweed)}}
{{Speciesbox
| image         = Capo Gallo 021.jpg
| image_caption = ''Halimeda tuna'' on the Sicilian coast
| image_alt     = Halimeda tuna
| genus         = Halimeda
| species       = tuna
| authority     = (J. Ellis & Solander) J. V. Lamouroux, 1816<ref name=WoRMS>{{cite WoRMS |author=Guiry, Michael D. |year=2019 |title=''Halimeda tuna'' (J.Ellis & Solander) J.V.Lamouroux, 1816 |id=144483 |accessdate=12 June 2019}}</ref>
| synonyms      = 
* ''Corallina tuna''<small> J.Ellis & Solander, 1768</small>
* ''Halimeda platydisca''<small> Decaisne, 1842</small>
* ''Halimeda tuna f. albertisii''<small> (Piccone) De Toni, 1889</small>
* ''Halimeda tuna f. platydisca''<small> (Decaisne) E.S.Barton, 1901</small>
* ''Halimeda tuna var. albertisii''<small> Piccone, 1883</small>
* ''Halimeda tuna var. platydisca''<small> (Decaisne) Børgesen, 1911</small>
| synonyms_ref  = <ref name=WoRMS/>
}}

'''''Halimeda tuna''''' is a species of [[Earth:Calcareous|calcareous]] green [[Biology:Seaweed|seaweed]] in the order [[Biology:Bryopsidales|Bryopsidales]]. It is found on reefs in the Atlantic Ocean, the Indo-Pacific region and the Mediterranean Sea. ''Halimeda tuna'' is the [[Biology:Type species|type species]] of the genus ''[[Biology:Halimeda|Halimeda]]'' and the type locality is the Mediterranean Sea. The specific name "tuna" comes from the Taíno language, meaning "cactus" and referring to the resemblance of the [[Biology:Thallus|thallus]] to the growth form of an ''[[Biology:Opuntia|Opuntia]]'' cactus.<ref>{{cite web |url=http://www.algaebase.org/search/species/detail/?species_id=1223 |title=''Halimeda tuna'' (J.Ellis & Solander) J.V.Lamouroux |author=Guiry, M.D. |publisher=AlgaeBase |accessdate=13 June 2019}}</ref>

== Description ==
''Halimeda tuna'' is a [[Earth:Calcareous|calcareous]] green seaweed, attached to the seabed by a [[Biology:Holdfast|holdfast]].<ref name=Ballesteros/> Each individual [[Biology:Thallus|thallus]] (frond) consists of a single [[Biology:Cell|cell]] forming a tube with multiple [[Biology:Cell nucleus|cell nuclei]]. The [[Biology:Cytoplasm|cytoplasm]] is mobile and the nuclei, [[Biology:Chloroplast|chloroplast]]s and other cell contents are free to move around inside the [[Biology:Cell wall|cell wall]].<ref>{{cite journal |author=Day, Robert |year=1996 |title=The Cell Biology of the Bryopsidales |journal=Seascope |volume=13 |url=http://www.angelfire.com/ri/skibizniz/bryopsidales.html}}</ref> The tube has flattened, disc-like segments connected by flexible joints. The surface of these segments have swollen areas called utricles which together make a tabular "cellular pavement". Below and between these utricles, there are gaps and it is here that the fluid is saturated with [[Chemistry:Calcium carbonate|calcium carbonate]] and crystalline needles of [[Chemistry:Aragonite|aragonite]] form. These stiffen the segments and make the seaweed unpalatable to fish. When the seaweed dies, this skeletal material breaks down into "sand". Members of this genus are likely to be one of the most important agents of calcification in the marine environment, considerably more productive in tropical seas than [[Biology:Scleractinia|stony corals]].{{cn|date=August 2020}}

== Distribution ==
This species is found in the tropical and subtropical Indo-Pacific region, the Mediterranean Sea and the western Atlantic Ocean. It grows on rocky reefs from the shallow subtidal zone down to depths of about {{convert|70|m|ft|0|abbr=on}}.<ref>{{cite web |url=https://www.sealifebase.ca/summary/Halimeda-tuna.html |title=''Halimeda tuna'' (J. Ellis & Solander) J.V. Lamouroux |work=SeaLifeBase |accessdate=12 June 2019}}</ref> In the Mediterranean Sea it occurs in two separate habitat types; shallow, warm lagoons and sheltered places in the central Mediterranean and deep water ({{convert|18|m|ft|-1|abbr=on}}) rocky habitats in the northwest Mediterranean.<ref name=Ballesteros>{{cite journal |author=Ballesteros, E. |s2cid=84207037 |year=1991 |title=Seasonality of Growth and Production of a Deep-water Population of ''Halimeda tuna'' (Chlorophyceae, Caulerpales) in the North-western Mediterranean |journal=Botanica Marina |volume=34 |issue=4 |pages=291–391 |doi=10.1515/botm.1991.34.4.291}}</ref> Similarly, in the Florida Keys, it is the dominant green alga in shallow back reef locations and in much deeper, less well lit, reef slope habitats.<ref name=Vroom>{{cite journal |author=Vroom, Peter S. |author2=Smith, Celia M. |author3=Coyer, James A. |author4=Walters, Linda J. |author5=Hunter, Cynthia L. |author6=Beach, Kevin S. |author7=Smith, Jennifer E. |s2cid=24672217 |year=2003 |title=Field biology of ''Halimeda tuna'' (Bryopsidales, Chlorophyta) across a depth gradient: comparative growth, survivorship, recruitment, and reproduction |journal=Hydrobiologia |volume=501 |issue=1–3 |pages=149–166 |doi=10.1023/A:1026287816324}}</ref>

== Ecology ==
The thallus of this seaweed is often overgrown by [[Earth:Epiphyte|epiphyte]]s which are at their maximum abundance in summer. The segments are sometimes damaged by storms, but are replaced by new growth which occurs with rising temperatures and increasing amounts of irradiation and dissolved nutrients.<ref name=Ballesteros/> In the deepwater habitats in the Mediterranean, it is the dominant species and is often found in association with the encrusting red alga ''[[Biology:Mesophyllum|Mesophyllum]] lichenoides''. In this habitat it tends to grow on vertical walls, under overhangs and in positions where it receives little sunlight. Its adaptation to dim light is assisted by its containing two accessory photosynthetic pigments, the green-absorbing [[Biology:Carotenoid|carotenoid]]s siphonein and siphonaxanthin, as well as [[Chemistry:Chlorophyll a|chlorophyll a]] and [[Chemistry:Chlorophyll b|chlorophyll b]].<ref>{{cite journal |author=Ballesteros, E. |year=1991 |title=Structure of a deep-water community of Halimeda tuna (Chlorophyceae, Caulerpales) from the North-Western Mediterranean |journal= Collectanea Botanica|volume=5 |pages=5–21 |url=https://www.researchgate.net/publication/45087051 |doi=10.3989/collectbot.1991.v20.72 |doi-access=free |hdl=10261/27800 |hdl-access=free }}</ref> In Florida, reproductive events occurred simultaneously across the reef, with up to 5% of thalli developing [[Biology:Gametangium|gametangia]]. Asexual reproduction also occurred through [[Medicine:Fragmentation (reproduction)|fragmentation]] or the growth of vegetative [[Biology:Stolon|stolon]]s.<ref name=Vroom/>

== Human uses ==
This seaweed has been described as pleasant to eat with oil, vinegar, and salt.<ref name="Bauhin">{{cite book|last1=Bauhin|first1=Jean|last2=Cherler|first2=Johann Heinrich|title=Historia plantarum [...] Tomus III|date=1651|publisher=Ebroduni|oclc=495081149|page=803|chapter-url=http://bibdigital.rjb.csic.es/ing/Libro.php?Libro=4182&Pagina=1015|accessdate=15 February 2018|language=Latin|chapter-format=PDF|chapter=Liber XXXIX|quote={{lang|la|Nà[m] Theophraftus (1. cap. hist. c. 12) scribit circa Opuntem herbulam effe quandam, quae ex foliis radicem mittat, ac cum suauitate mandi possit. Plinius verò ipsum sequutus (lib. 21.cap.17) circa Opuntem, inquit, Opuntia est herba, etiam homini-dulcis: mirúmque è folio ejus radicem fieri, ac sic eam nasci. Et certè credibile est hanc plantam recentem cum aceto, sale, & oleo, vel etiam sine sale, non minùs suauiter edi posse quàm Portulacae marinae & sìmilium folia.}}|archive-date=16 February 2018|archive-url=https://web.archive.org/web/20180216030323/http://bibdigital.rjb.csic.es/ing/Libro.php?Libro=4182&Pagina=1015|url-status=dead}}</ref><ref name="Hills-Colinvaux">{{Cite book|last1=Hills-Colinvaux|first1=Llewellya|editor1-last=Baxter|editor1-first=J.H.S.|editor2-last=Russell|editor2-first=Frederick S.|editor3-last=Yonge|editor3-first=Maurice|title=Ecology and Taxonomy of ''Halimeda'': Primary Producer of Coral Reefs|journal=Advances in Marine Biology|date=27 May 1980|volume=17 |pages=17–18 |url=https://books.google.com/books?id=rgPCtSt15roC&dq=Halimeda%20salt%20vinegar%20oil&pg=PA17 |accessdate=15 February 2018|publisher=Academic Press |language=English |format=PDF |isbn=9780080579405|oclc=476214112}}</ref>

== References ==
{{Reflist|30em}}

== External links ==

{{Taxonbar|from=Q3021618}}

[[Category:Bryopsidales]]

{{Sourceattribution|Halimeda tuna}}