Dinoflagellate#sulcus

The term "dinoflagellate" is a combination of the Greek dinos and the Latin flagellum. Dinos means "whirling" and signifies the distinctive way in which dinoflagellates were observed to swim. Flagellum means "whip" and this refers to their flagella.{{cite book | vauthors = Carty S, Parrow MW |chapter=Dinoflagellates |title=Freshwater Algae of North America |publisher=Academic Press |date=2015 |pages=773–807 |doi=10.1016/B978-0-12-385876-4.00017-7 |isbn=978-0-12-385876-4}}

In 1753, the first modern dinoflagellates were described by Henry Baker as "Animalcules which cause the Sparkling Light in Sea Water",{{cite book | vauthors = Baker M |date=1753 |title=Employment for the microscope |publisher=Dodsley |location=London |oclc=722119426 |url=http://catalog.hathitrust.org/api/volumes/oclc/4322834.html |doi=10.5962/bhl.title.45920 }} and named by Otto Friedrich Müller in 1773.Müller, O.F. 1773. Vermium terrestrium et fluviatilium, seu Animalium Infusoriorum, Helmithicorum et Testaceorum, non marinorum, succincta historia, vol. 1. Pars prima. p. 34, 135. Faber, Havniae, et Lipsiae 1773.

In the 1830s, the German microscopist Christian Gottfried Ehrenberg examined many water and plankton samples and proposed several dinoflagellate genera that are still used today including Peridinium, Prorocentrum, and Dinophysis.Ehrenberg C.G. (1832) Beiträge zur Kenntnis der Organisation der Infusorien und ihrer geographischer Verbreitung, besonders in Sibirien. — Abhandlungen der Königlichen Akademie der Wissenschaften zu Berlin. Aus dem Jahre 1830. Physikalische Abhandlungen 1830: 1–88, Pls 1–8.

These same dinoflagellates were first defined by Otto Bütschli in 1885 as the flagellate order Dinoflagellida.Bütschli O. (1885) 3. Unterabtheilung (Ordnung) Dinoflagellata. – In: Dr. H.G. Bronn's Klassen und Ordnungen des Thier-Reichs, wissenschaftlich dargestellt in Wort und Bild. Erster Band Protozoa. – C.F. Winter'sche Verlagshandlung, Leipzig und Heidelberg. Pp. 906–1029; Pl. Botanists treated them as a division of algae, named Pyrrophyta or Pyrrhophyta ("fire algae"; Greek pyrr(h)os, fire) after the bioluminescent forms, or Dinophyta. At various times, the cryptomonads, ebriids, and ellobiopsids have been included here, but only the last are now considered close relatives. Dinoflagellates have a known ability to transform from noncyst to cyst-forming strategies, which makes recreating their evolutionary history extremely difficult.

File:2023 Dinoflagellate.svg membranes (3, secondary red)|

|Thylakoids, site of the light-dependent reactions of photosynthesis|

Pyrenoid, center of carbon fixation|

Trichocyst|

Alveolus, surface cavity or pit|

Thecal plate|

Sac pusule|

Vacuome|

Golgi apparatus; modifies proteins and sends them out of the cell|

Endoplasmic reticulum, the transport network for molecules going to specific parts of the cell|

Transverse flagellum|

Striated strand|

Collecting pusule|

Mitochondrion, creates ATP (energy) for the cell|

Nucleus|

Nucleolus|

Condensed chromosome|

Starch granule|

Lysosome, holds enzymes|

|Phagosome, vesicle formed around a particle|

Mastigoneme, "hairs" that attached to flagellum|

Longitudinal flagellum}}]]

{{anchor|flagellum|axoneme}}Dinoflagellates are unicellular and possess two dissimilar flagella arising from the ventral cell side (dinokont flagellation). They have a ribbon-like transverse flagellum with multiple waves that beats to the cell's left, and a more conventional one, the longitudinal flagellum, that beats posteriorly.{{cite journal |author=Taylor FJR |title=Non-helical transverse flagella in dinoflagellates |journal=Phycologia |volume=14 |pages=45–7 |date=March 1975 |issue=1 |doi=10.2216/i0031-8884-14-1-45.1 |bibcode=1975Phyco..14...45T }}{{cite journal | vauthors = Leblond PH, Taylor FJ | title = The propulsive mechanism of the dinoflagellate transverse flagellum reconsidered | journal = Bio Systems | volume = 8 | issue = 1 | pages = 33–39 | date = April 1976 | pmid = 986199 | doi = 10.1016/0303-2647(76)90005-8 | bibcode = 1976BiSys...8...33L }}{{cite journal |vauthors=Gaines G, Taylor FJ |title=Form and function of the dinoflagellate transverse flagellum |journal=J. Protozool. |volume=32 |issue=2 |pages=290–6 |date=May 1985 |doi=10.1111/j.1550-7408.1985.tb03053.x }} The transverse flagellum is a wavy ribbon in which only the outer edge undulates from base to tip, due to the action of the axoneme which runs along it. The axonemal edge has simple hairs that can be of varying lengths. The flagellar movement produces forward propulsion and also a turning force. The longitudinal flagellum is relatively conventional in appearance, with few or no hairs. It beats with only one or two periods to its wave. The flagella lie in surface grooves: the transverse one in the cingulum and the longitudinal one in the sulcus, although its distal portion projects freely behind the cell. In dinoflagellate species with desmokont flagellation (e.g., Prorocentrum), the two flagella are differentiated as in dinokonts, but they are not associated with grooves.

{{anchor|amphiesma|cortex|alveoli|theca|lorica|thecate|athecate|tabulation}}Dinoflagellates have a complex cell covering called an amphiesma or cortex, composed of a series of membranes, flattened vesicles called alveoli (= amphiesmal vesicles) and related structures.{{Cite book | vauthors = Morrill LC, Loeblich AR | title = Ultrastructure of the Dinoflagellate Amphiesma | volume = 82 | pages = 151–80 | year = 1983 | pmid = 6684652 | doi = 10.1016/s0074-7696(08)60825-6 | isbn = 978-0-1236-4482-4 | series = International Review of Cytology }}{{cite book | vauthors = Netzel H, Dürr G |title=Ch. 3: Dinoflagellate cell cortex |url=https://books.google.com/books?id=qCcgFximE8oC&pg=PA43 |pages=43–106 |isbn=978-0-3231-3813-0 |date=2012-12-02 |publisher=Academic Press |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707092010/http://books.google.com/books?id=qCcgFximE8oC&pg=PA43 |url-status=live }} In {{harvnb|Spector|1984}} In thecate ("armoured") dinoflagellates, these support overlapping cellulose plates to create a sort of armor called the theca or lorica, as opposed to athecate ("nude") dinoflagellates. These occur in various shapes and arrangements, depending on the species and sometimes on the stage of the dinoflagellate. Conventionally, the term tabulation has been used to refer to this arrangement of thecal plates. The plate configuration can be denoted with the plate formula or tabulation formula. Fibrous extrusomes are also found in many forms.

{{anchor|cingulum|epitheca|hypotheca|episoma|hyposoma|cingulim|cigulum|sulcus}}A transverse groove, the so-called cingulum (or cigulum) runs around the cell, thus dividing it into an anterior (episoma) and posterior (hyposoma). If and only if a theca is present, the parts are called epitheca and hypotheca, respectively. Posteriorly, starting from the transverse groove, there is a longitudinal furrow called the sulcus. The transverse flagellum strikes in the cingulum, the longitudinal flagellum in the sulcus.{{cite journal | vauthors = Trench RK, Blank RJ |year=1987 |title=Symbiodinium microadriaticum Freudenthal, S. goreauii sp. nov., S. kawagutii sp. nov. And S. pilosum sp. nov.: Gymnodinioid Dinoflagellate Symbionts of Marine Invertebrates |journal=Journal of Phycology |volume=23 |issue=3 |pages=469–81 |doi=10.1111/j.1529-8817.1987.tb02534.x|bibcode=1987JPcgy..23..469T |s2cid=83712799 }}{{cite journal | vauthors = Freudenthal HD |year=1962 |title=Symbiodinium gen. Nov. And Symbiodinium microadriaticum sp. nov., a Zooxanthella: Taxonomy, Life Cycle, and Morphology |journal=The Journal of Protozoology |volume=9 |issue=1 |pages=45–52 |doi=10.1111/j.1550-7408.1962.tb02579.x}}

Together with various other structural and genetic details, this organization indicates a close relationship between the dinoflagellates, the Apicomplexa, and ciliates, collectively referred to as the alveolates.{{cite book | vauthors = Cavalier-Smith T |chapter=Cell diversification in heterotrophic flagellates | veditors = Patterson DJ, Larsen J |title=The biology of free-living heterotrophic flagellates |publisher=Clarendon Press |series=Systematics Association Publications |year=1991 |isbn=978-0-1985-7747-8 |pages=113–131 |volume=45 }}

Dinoflagellate tabulations can be grouped into six "tabulation types": gymnodinoid, suessoid, gonyaulacoid–peridinioid, nannoceratopsioid, dinophysioid, and prorocentroid.{{cite book | vauthors = Medlin LK, Fensome RA | chapter = Dinoflagellate macroevolution | title = Biological and Geological Perspectives of Dinoflagellates |pages=263–274 |publisher=Geological Society of London |doi=10.1144/tms5.25 |isbn=978-1-86239-368-4 |date=2013 }}

Most Dinoflagellates have a plastid derived from secondary endosymbiosis of red algae, however dinoflagellates with plastids derived from green algae and tertiary endosymbiosis of diatoms have also been discovered.{{cite journal | vauthors = Keeling PJ | title = The endosymbiotic origin, diversification and fate of plastids | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 365 | issue = 1541 | pages = 729–748 | date = March 2010 | pmid = 20124341 | pmc = 2817223 | doi = 10.1098/rstb.2009.0103 }} Similar to other photosynthetic organisms, dinoflagellates contain chlorophylls a and c2 and the carotenoid beta-carotene. Dinoflagellates also produce the xanthophylls including peridinin, dinoxanthin, and diadinoxanthin. These pigments give many dinoflagellates their typical golden brown color. However, the dinoflagellates Karenia brevis, Karenia mikimotoi, and Karlodinium micrum have acquired other pigments through endosymbiosis, including fucoxanthin.{{cite journal | vauthors = Hackett JD, Anderson DM, Erdner DL, Bhattacharya D | title = Dinoflagellates: a remarkable evolutionary experiment | journal = American Journal of Botany | volume = 91 | issue = 10 | pages = 1523–1534 | date = October 2004 | pmid = 21652307 | doi = 10.3732/ajb.91.10.1523 }}

This suggests their chloroplasts were incorporated by several endosymbiotic events involving already colored or secondarily colorless forms. The discovery of plastids in the Apicomplexa has led some to suggest they were inherited from an ancestor common to the two groups, but none of the more basal lines has them.

All the same, the dinoflagellate cell consists of the more common organelles such as rough and smooth endoplasmic reticulum, Golgi apparatus, mitochondria, lipid and starch grains, and food vacuoles. Some have even been found with a light-sensitive organelle, the eyespot or stigma, or a larger nucleus containing a prominent nucleolus. The dinoflagellate Erythropsidinium has the smallest known eye.{{cite journal | vauthors = Schwab IR | title = You are what you eat | journal = The British Journal of Ophthalmology | volume = 88 | issue = 9 | pages = 1113 | date = September 2004 | pmid = 15352316 | pmc = 1772300 | doi = 10.1136/bjo.2004.049510 }}

Some athecate species have an internal skeleton consisting of two star-like siliceous elements that has an unknown function, and can be found as microfossils. Tappan{{cite book | vauthors = Tappan HN |title=The Paleobiology of Plant Protists |publisher=W.H. Freeman |series=Geology |year=1980 |isbn=978-0-7167-1109-4 }} gave a survey of dinoflagellates with internal skeletons. This included the first detailed description of the pentasters in Actiniscus pentasterias, based on scanning electron microscopy. They are placed within the order Gymnodiniales, suborder Actiniscineae.

The formation of thecal plates has been studied in detail through ultrastructural studies.

{{Main|Dinokaryon}}

'Core dinoflagellates' (dinokaryotes) have a peculiar form of nucleus, called a dinokaryon, in which the chromosomes are attached to the nuclear membrane. These carry reduced number of histones. In place of histones, dinoflagellate nuclei contain a novel, dominant family of nuclear proteins that appear to be of viral origin, thus are called Dinoflagellate viral nucleoproteins (DVNPs) which are highly basic, bind DNA with similar affinity to histones, and occur in multiple posttranslationally modified forms.{{cite journal | vauthors = Gornik SG, Ford KL, Mulhern TD, Bacic A, McFadden GI, Waller RF | title = Loss of nucleosomal DNA condensation coincides with appearance of a novel nuclear protein in dinoflagellates | journal = Current Biology | volume = 22 | issue = 24 | pages = 2303–2312 | date = December 2012 | pmid = 23159597 | doi = 10.1016/j.cub.2012.10.036 | doi-access = free | bibcode = 2012CBio...22.2303G }} Dinoflagellate nuclei remain condensed throughout interphase rather than just during mitosis, which is closed and involves a uniquely extranuclear mitotic spindle.{{cite book | vauthors = Spector DL |title=Dinoflagellate nuclei |url=https://books.google.com/books?id=qCcgFximE8oC&pg=PA107 |pages=107–147 |isbn=978-0-3231-3813-0 |date=2012-12-02 |publisher=Academic Press |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707091832/http://books.google.com/books?id=qCcgFximE8oC&pg=PA107 |url-status=live }} In {{harvnb|Spector|1984}} This sort of nucleus was once considered to be an intermediate between the nucleoid region of prokaryotes and the true nuclei of eukaryotes, so were termed "mesokaryotic", but now are considered derived rather than primitive traits (i. e. ancestors of dinoflagellates had typical eukaryotic nuclei). In addition to dinokaryotes, DVNPs can be found in a group of basal dinoflagellates (known as Marine Alveolates, "MALVs") that branch as sister to dinokaryotes (Syndiniales).{{cite journal | vauthors = Strassert JF, Karnkowska A, Hehenberger E, Del Campo J, Kolisko M, Okamoto N, Burki F, Janouškovec J, Poirier C, Leonard G, Hallam SJ, Richards TA, Worden AZ, Santoro AE, Keeling PJ | title = Single cell genomics of uncultured marine alveolates shows paraphyly of basal dinoflagellates | journal = The ISME Journal | volume = 12 | issue = 1 | pages = 304–308 | date = January 2018 | pmid = 28994824 | pmc = 5739020 | doi = 10.1038/ismej.2017.167 | url = http://discovery.ucl.ac.uk/10030027/ | access-date = 2018-10-23 | url-status = live | type = Submitted manuscript | bibcode = 2018ISMEJ..12..304S | archive-url = https://web.archive.org/web/20181214193922/http://discovery.ucl.ac.uk/10030027/ | archive-date = 2018-12-14 }}

{{Further|Wikispecies:Dinoflagellata}}

File:Britannica Dinoflagellata 2.jpg; 2. diagram; 3. Exuviaella; 4. Prorocentrum; 5, 6. Ceratium; 7. Warnowia; 8. Citharistes; 9. Polykrikos]]

Dinoflagellates are protists and have been classified using both the International Code of Botanical Nomenclature (ICBN, now renamed as ICN) and the International Code of Zoological Nomenclature (ICZN). About half of living dinoflagellate species are autotrophs possessing chloroplasts and half are nonphotosynthesising heterotrophs.

The peridinin dinoflagellates, named after their peridinin plastids, appear to be ancestral for the dinoflagellate lineage. Almost half of all known species have chloroplasts, which are either the original peridinin plastids or new plastids acquired from other lineages of unicellular algae through endosymbiosis. The remaining species have lost their photosynthetic abilities and have adapted to a heterotrophic, parasitic or kleptoplastic lifestyle.{{cite journal | vauthors = Gabrielsen TM, Minge MA, Espelund M, Tooming-Klunderud A, Patil V, Nederbragt AJ, Otis C, Turmel M, Shalchian-Tabrizi K, Lemieux C, Jakobsen KS | title = Genome evolution of a tertiary dinoflagellate plastid | journal = PLOS ONE | volume = 6 | issue = 4 | pages = e19132 | date = April 2011 | pmid = 21541332 | pmc = 3082547 | doi = 10.1371/journal.pone.0019132 | doi-access = free | bibcode = 2011PLoSO...619132G }}{{cite journal|doi=10.1080/09670260600961080 | volume=41 | title=Did the peridinin plastid evolve through tertiary endosymbiosis? A hypothesis | year=2006 | journal=European Journal of Phycology | pages=435–448 | vauthors = Bodył A, Moszczyński K | issue=4 | doi-access=free | bibcode=2006EJPhy..41..435B }}

Most (but not all) dinoflagellates have a dinokaryon, described below (see: Life cycle, below). Dinoflagellates with a dinokaryon are classified under Dinokaryota, while dinoflagellates without a dinokaryon are classified under Syndiniales.

Although classified as eukaryotes, the dinoflagellate nuclei are not characteristically eukaryotic, as some of them lack histones and nucleosomes, and maintain continually condensed chromosomes during mitosis. The dinoflagellate nucleus was termed 'mesokaryotic' by Dodge (1966),Dodge (1966). Cited but unreferenced in {{cite book |author1=Steidinger KA |author2=Jangen K |chapter=Dinoflagellates | veditors = Tomas CR |year=1997 |title=Identifying Marine Phytoplankton |chapter-url=https://books.google.com/books?id=8WLABHmo-K8C&pg=PA387 |publisher=Academic Press |isbn=978-0-0805-3442-8 |pages=387–584 |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707091615/http://books.google.com/books?id=8WLABHmo-K8C&pg=PA387 |url-status=live }} due to its possession of intermediate characteristics between the coiled DNA areas of prokaryotic bacteria and the well-defined eukaryotic nucleus. This group, however, does contain typically eukaryotic organelles, such as Golgi bodies, mitochondria, and chloroplasts.{{cite book |vauthors=Steidinger KA, Jangen K |chapter=Dinoflagellates |veditors=Tomas CR |year=1997 |title=Identifying Marine Phytoplankton |chapter-url=https://books.google.com/books?id=8WLABHmo-K8C&pg=PA387 |publisher=Academic Press |isbn=978-0-0805-3442-8 |pages=387–584 |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707091615/http://books.google.com/books?id=8WLABHmo-K8C&pg=PA387 |url-status=live }}

File:Динофитовая микроводоросль, выделенная из осадков Амурского залива в 2020 году.jpg]]

Jakob Schiller (1931–1937) provided a description of all the species, both marine and freshwater, known at that time.Schiller, J., 1931–1937: Dinoflagellatae (Peridinineae) in monographischer Behandlung. In: RABENHORST, L. (ed.), Kryptogamen-Flora von Deutschland, Österreichs und der Schweiz. Akad. Verlag., Leipzig. Vol. 10 (3): Teil 1 (1–3) (1931–1933): Teil 2 (1–4)(1935–1937). Later, Alain Sournia (1973, 1978, 1982, 1990, 1993) listed the new taxonomic entries published after Schiller (1931–1937).{{cite journal |author=Sournia A |title=Catalogue des espèces et taxons infraspécifiques de dinoflagellés marins actuels publiés depuis la révision de J. Schiller. I. Dinoflagellés libres |journal=Beih. Nova Hedwigia |volume=48 |pages=1–92 |year=1973 }}{{cite journal |author=Sournia A |title=Catalogue des espèces et taxons infraspécifiques de dinoflagellésmarins actuels publiés depuis la révision de J. Schiller. III (Complément) |journal=Rev. Algol. |volume=13 |pages=3–40 +erratum 13, [https://www.biodiversitylibrary.org/item/281442#page/4/mode/1up 186] |year=1978 |url=https://www.biodiversitylibrary.org/item/281428#page/4/mode/2up |issn=0035-0702}}{{cite journal |author=Sournia A |title=Catalogue des espèces et taxons infraspécifiques de dinoflagellésmarins actuels publiés depuis la révision de J. Schiller. IV. (Complément) |journal=Arch. Protistenkd. |volume=126 |issue= 2|pages=151–168 |year=1982 |doi=10.1016/S0003-9365(82)80046-8 }}{{cite journal |author=Sournia A |title=Catalogue des espèces et taxons infraspécifiques de dinoflagellésmarins actuels publiés depuis la révision de J. Schiller. V. (Complément) |journal=Acta Protozool. |volume=29 |pages=321–346 |year=1990 |issn=0065-1583}}{{cite journal |author=Sournia A |title=Catalogue des espèces et taxons infraspécifiques de dinoflagellésmarins actuels publiés depuis la révision de J. Schiller. VI. (Complément) |journal=Cryptog. Algol. |volume=14 |pages=133–144 |year=1993 |issue=2–3 |doi=10.5962/p.309374 |bibcode=1993CrypA..14..133S |issn=0181-1568 |url=https://www.biodiversitylibrary.org/part/309374 }} Sournia (1986) gave descriptions and illustrations of the marine genera of dinoflagellates, excluding information at the species level.SOURNIA, A., 1986: Atlas du Phytoplancton Marin. Vol. I: Introduction, Cyanophycées,Dictyochophycées, Dinophycées et Raphidophycées. Editions du CNRS, Paris. The latest index is written by Gómez.

English-language taxonomic monographs covering large numbers of species are published for the Gulf of Mexico,{{cite book | vauthors = Steidinger KA, Williams J |title=Dinoflagellates |publisher=Marine Research Laboratory |location=Florida |year=1970 |series=Memoirs of the Hourglass Cruises |oclc=6206528 |volume=2 }} the Indian Ocean,{{cite book | vauthors = Taylor FJ, Hart-Jones B |title=Dinoflagellates from the International Indian Ocean Expedition: A Report on Material Collected by the R.V. "Anton Bruun" 1963–1964 |publisher=E. Schweizerbart |series=Biblioteca Botanica |year=1976 |isbn=978-3-5104-8003-6 |volume=132 |oclc=3026853 }} the British Isles,{{cite book | vauthors = Dodge JD |date=1982 |title=Marine Dinoflagellates of the British Isles |publisher=Her Majesty's Stationery Office |location=London |isbn=9780112411963 |oclc=681855348 |url=http://catalog.hathitrust.org/api/volumes/oclc/9407842.html}} the Mediterranean{{cite journal |author=Gómez F |title=Checklist of Mediterranean free-living dinoflagellates |journal=Botanica Marina |volume=46 |issue=3 |pages=215–242 |date=April 2003 |doi=10.1515/BOT.2003.021 |bibcode=2003BoMar..46...21G |s2cid=84744638 }} and the North Sea.{{cite book | vauthors = Hoppenrath M, Elbrächter M, Drebes G |title=Marine phytoplankton: selected microphytoplankton species from the North Sea around Helgoland and Sylt |publisher=E. Schweizerbart'sche Verlagsbuchhandlung (Nägele und Obermiller) |location=Stuttgart |year=2009 |isbn=978-3-5106-1392-2 }}

The main source for identification of freshwater dinoflagellates is the Süsswasser Flora.{{cite book |vauthors=Popovský J, Pfiester LA |title=Dinophyceae (Dinoflagellida) |publisher=Fischer |series=Süßwasserflora von Mitteleuropa |volume=6 |year=1990 |isbn=978-3-3340-0247-6 |url=https://books.google.com/books?id=MXIVAQAAIAA }}{{Dead link|date=November 2023 |bot=InternetArchiveBot |fix-attempted=yes }}

Calcofluor-white can be used to stain thecal plates in armoured dinoflagellates.{{cite journal |vauthors=Fritz L, Triemer R |title=A rapid simple technique utilizing calcofluor white M2R for the visualization of dinoflagellate thecal plates |journal=J. Phycol. |volume=21 |issue=4 |pages=662–664 |date=December 1985 |doi=10.1111/j.0022-3646.1985.00662.x |bibcode=1985JPcgy..21..662F |s2cid=85004940 }}

Dinoflagellates are found in all aquatic environments: marine, brackish, and fresh water, including in snow or ice. They are also common in benthic environments and sea ice.

All Zooxanthellae are dinoflagellates and most of them are members within Symbiodiniaceae (e.g. the genus Symbiodinium).Freudenthal et al. 2007 The association between Symbiodinium and reef-building corals is widely known. However, endosymbiontic Zooxanthellae inhabit a great number of other invertebrates and protists, for example many sea anemones, jellyfish, nudibranchs, the giant clam Tridacna, and several species of radiolarians and foraminiferans.{{cite book | vauthors = Trench RK |chapter=Diversity of symbiotic dinoflagellates and the evolution of microalgal-invertebrate symbioses |chapter-url=http://www.reefbase.org/download/download.aspx?type=1&docid=8278 | veditors = Lessios HA, MacIntyre IG |title=Proceedings of the eighth International Coral Reef Symposium, Panama, June 24–29, 1996 |publisher=Smithsonian Tropical Research Institute |location=Balboa, Panama |year=1997 |oclc=833272061 |pages=1275–86 |volume=2 }} Many extant dinoflagellates are parasites (here defined as organisms that eat their prey from the inside, i.e. endoparasites, or that remain attached to their prey for longer periods of time, i.e. ectoparasites). They can parasitize animal or protist hosts. Protoodinium, Crepidoodinium, Piscinoodinium, and Blastodinium retain their plastids while feeding on their zooplanktonic or fish hosts. In most parasitic dinoflagellates, the infective stage resembles a typical motile dinoflagellate cell.

Three nutritional strategies are seen in dinoflagellates: phototrophy, mixotrophy, and heterotrophy. Phototrophs can be photoautotrophs or auxotrophs. Mixotrophic dinoflagellates are photosynthetically active, but are also heterotrophic. Facultative mixotrophs, in which autotrophy or heterotrophy is sufficient for nutrition, are classified as amphitrophic. If both forms are required, the organisms are mixotrophic sensu stricto. Some free-living dinoflagellates do not have chloroplasts, but host a phototrophic endosymbiont. A few dinoflagellates may use alien chloroplasts (cleptochloroplasts), obtained from food (kleptoplasty). Some dinoflagellates may feed on other organisms as predators or parasites.{{cite journal | vauthors = Schnepf E, Elbrächter M | title = Nutritional strategies in dinoflagellates: A review with emphasis on cell biological aspects | journal = European Journal of Protistology | volume = 28 | issue = 1 | pages = 3–24 | date = February 1992 | pmid = 23194978 | doi = 10.1016/S0932-4739(11)80315-9 }}

{{anchor|peduncle}}Food inclusions contain bacteria, bluegreen algae, diatoms, ciliates, and other dinoflagellates.{{cite journal |author1-link=Charles Atwood Kofoid |author2-link=Olive Swezy |vauthors=Kofoid CA, Swezy O |title=The free-living unarmoured dinoflagellata |journal=Mere. Univ. Calif. |volume=5 |pages=1–538 |year=1921 |doi=10.5962/bhl.title.24995 |url=https://www.biodiversitylibrary.org/itempdf/66471 |access-date=2019-09-24 |archive-date=2022-05-15 |archive-url=https://web.archive.org/web/20220515071419/https://ia600900.us.archive.org/14/items/freelivingunarmo00kofouoft/freelivingunarmo00kofouoft.pdf |url-status=live }}{{cite journal |author=Barker HA |title=The culture and physiology of the marine dinoflagellates |journal=Arch. Mikrobiol. |volume=6 |issue=1–5 |pages=157–181 |year=1935 |doi=10.1007/BF00407285 |bibcode=1935ArMic...6..157B |s2cid=44657010 }}{{cite journal |author=Biecheler B |title=Recherches sur les Peridiniens |journal=Bull. Biol. Fr. Belg. |volume=36 |issue=Suppl |pages=1–149 |year=1952 |issn=0994-575X}}

{{cite journal |author=Bursa AS |title=The annual oceanographic cycle at Igloolik in the Canadian Arctic. II. The phytoplankton |journal=J. Fish. Res. Board Can. |volume=18 |issue=4 |pages=563–615 |year=1961 |doi=10.1139/f61-046 }}{{cite journal |author=Norris DR |title=Possible phagotrophic feeding in Ceratium lunula Schimper |journal=Limnol. Oceanogr. |volume=14 |issue=3 |pages=448–9 |year=1969 |doi=10.4319/lo.1969.14.3.0448 |bibcode=1969LimOc..14..448N |doi-access=free }}{{cite journal |vauthors=Dodge JD, Crawford RM |title=The morphology and fine structure of Ceratium hirundinella (Dinophyceae) |journal=J. Phycol. |volume=6 |issue=2 |pages=137–149 |date=June 1970 |doi=10.1111/j.1529-8817.1970.tb02372.x |bibcode=1970JPcgy...6..137D |s2cid=84034844 }}{{cite journal |author=Elbrachter M |title=On the taxonomy of unarmored dinophytes (Dinophyta) from the Northwest African upwelling region |journal=Meteor Forschungsergebnisse |volume=30 |pages=1–22 |year=1979 }}

Mechanisms of capture and ingestion in dinoflagellates are quite diverse. Several dinoflagellates, both thecate (e.g. Ceratium hirundinella, Peridinium globulus) and nonthecate (e.g. Oxyrrhis marina, Gymnodinium sp.{{cite journal |vauthors=Frey LC, Stoermer EF |title=Dinoflagellate phagotrophy in the upper Great Lakes |journal=Trans. Am. Microsc. Soc. |volume=99 |issue= 4|pages=439–444 |year=1980 |doi=10.2307/3225654 |jstor=3225654 }} and Kofoidinium spp.{{cite journal |vauthors=Cachon PJ, Cachon M |title=Le systeme stomatopharyngien de Kofoidinium Pavillard. Comparisons avec celui divers Peridiniens fibres et parasites |journal=Protistologica |volume=10 |pages=217–222 }}), draw prey to the sulcal region of the cell (either via water currents set up by the flagella or via pseudopodial extensions) and ingest the prey through the sulcus. In several Protoperidinium spp., e.g. P. conicum, a large feeding veil—a pseudopod called the pallium—is extruded to capture prey which is subsequently digested extracellularly (= pallium-feeding).{{cite journal |vauthors=Gaines G, Taylor FJ |title=Extracellular digestion in marine dinoflagellates |journal=J. Plankton Res. |volume=6 |issue=6 |pages=1057–61 |year=1984 |doi=10.1093/plankt/6.6.1057 }}{{cite journal |vauthors=Jacobson DM, Anderson DM |title=Thecate heterotrophic dinoflagellates: feeding behavior and mechanisms |journal=J. Phycol. |volume=22 |issue=3 |pages=249–258 |date=September 1986 |doi=10.1111/j.1529-8817.1986.tb00021.x |s2cid=84321400 }} Oblea, Zygabikodinium, and Diplopsalis are the only other dinoflagellate genera known to use this particular feeding mechanism.{{cite journal |vauthors=Strom SL, Buskey EJ |title=Feeding, growth, and behavior of the thecate heterotrophic dinoflagellate Oblea rotunda |journal=Limnol. Oceanogr. |volume=38 |issue=5 |pages=965–977 |year=1993 |doi=10.4319/lo.1993.38.5.0965 |bibcode=1993LimOc..38..965S |doi-access=free }}{{cite journal |author=Naustvoll LJ |title=Growth and grazing by the thecate heterotrophic dinoflagellates Diplopsalis lenticula (Diplopsalidaceae, Dinophyceae) |journal=Phycologia |volume=37 |issue=1 |pages=1–9 |date=January 1998 |doi=10.2216/i0031-8884-37-1-1.1 |bibcode=1998Phyco..37....1N }}

Gymnodinium fungiforme, commonly found as a contaminant in algal or ciliate cultures, feeds by attaching to its prey and ingesting prey cytoplasm through an extensible peduncle.{{cite journal |author=Spero HJ |title=Phagotrophy in Gymnodinium fungiforme (Pyrrophyta): the peduncle as an organelle of ingestion |journal=J. Phycol. |volume=18 |issue=3 |pages=356–360 |date=September 1982 |doi=10.1111/j.1529-8817.1982.tb03196.x |bibcode=1982JPcgy..18..356S |s2cid=85988790 }} Two related genera, Polykrikos and Neatodinium, shoot out a harpoon-like organelle to capture prey.{{Cite web |url=https://phys.org/news/2017-04-capture-dinoflagellate-video-harpoons-prey.html |title=Researchers capture dinoflagellate on video shooting harpoons at prey |access-date=2019-05-19 |archive-date=2019-12-28 |archive-url=https://web.archive.org/web/20191228081132/https://phys.org/news/2017-04-capture-dinoflagellate-video-harpoons-prey.html |url-status=live }}

Some mixotrophic dinoflagellates are able to produce neurotoxins that have anti-grazing effects on larger copepods and enhance the ability of the dinoflagellate to prey upon larger copepods. Toxic strains of Karlodinium veneficum produce karlotoxin that kills predators who ingest them, thus reducing predatory populations and allowing blooms of both toxic and non-toxic strains of K. veneficum. Further, the production of karlotoxin enhances the predatory ability of K. veneficum by immobilizing its larger prey.{{cite journal | vauthors = Adolf JE, Krupatkina D, Bachvaroff T, Place AR |title=Karlotoxin mediates grazing by Oxyrrhis marina on strains of Karlodinium veneficum |journal=Harmful Algae |volume=6 |issue=3 |pages=400–412 |date=2007 |doi = 10.1016/j.hal.2006.12.003|bibcode=2007HAlga...6..400A }} K. armiger are more inclined to prey upon copepods by releasing a potent neurotoxin that immobilizes its prey upon contact. When K. armiger are present in large enough quantities, they are able to cull whole populations of their copepod prey.{{cite journal | vauthors = Berge T, Poulsen LK, Moldrup M, Daugbjerg N, Juel Hansen P | title = Marine microalgae attack and feed on metazoans | journal = The ISME Journal | volume = 6 | issue = 10 | pages = 1926–1936 | date = October 2012 | pmid = 22513533 | pmc = 3446796 | doi = 10.1038/ismej.2012.29 | bibcode = 2012ISMEJ...6.1926B }}

The feeding mechanisms of the oceanic dinoflagellates remain unknown, although pseudopodial extensions were observed in Podolampas bipes.{{cite book |last=Schütt |first=F. |chapter=2. Teil, Studien über die Zellen der Peridineen |title=Die Peridineen der Plankton-Expedition |publisher=Allgemeiner Theil |series=Ergebnisse der Plankton-Expedition der Humboldt-Stiftung |year=1895 |oclc=69377189 |pages=1–170 }}

Dinoflagellates possess a distinctive suite of photosynthetic pigments that allow them to survive and grow in a variety of aquatic environments. Like other phytoplankton, many dinoflagellates contain chlorophyll a and chlorophyll c, which are essential for photosynthesis and light energy capture.{{Cite book |last1=Jeffrey |first1=S. W. |url=https://figshare.utas.edu.au/articles/chapter/Microalgal_classes_and_their_signature_pigments/23056505 |title=Microalgal classes and their signature pigments |last2=Wright |first2=Simon |last3=Zapata |first3=M. |date=2011-01-01 |publisher=University of Tasmania |isbn=978-0-511-73226-3 |language=en}} However, unlike green algae and higher plants, they lack chlorophyll b. Instead, they utilize chlorophyll c2, which is more efficient for absorbing blue-green light, making them well adapted to low-light or deeper water conditions.{{Cite journal |last1=Schlüter |first1=L |last2=Møhlenberg |first2=F |last3=Havskum |first3=H |last4=Larsen |first4=S |date=2000 |title=The use of phytoplankton pigments for identifying and quantifying phytoplankton groups in coastal areas:testing the influence of light and nutrients on pigment/chlorophyll a ratios |journal=Marine Ecology Progress Series |language=en |volume=192 |pages=49–63 |doi=10.3354/meps192049 |bibcode=2000MEPS..192...49S |s2cid=56561696 |issn=0171-8630}} These pigments, along with carotenoids, contribute to the characteristic coloration of dinoflagellates, which can range from golden-brown to red.

A unique pigment in dinoflagellates is peridinin, a specialized carotenoid that plays a key role in light harvesting and energy transfer to chlorophyll a.{{Cite journal |last=Takaichi |first=Shinichi |date=2011 |title=Carotenoids in algae: distributions, biosyntheses and functions |journal=Marine Drugs |volume=9 |issue=6 |pages=1101–1118 |doi=10.3390/md9061101 |doi-access=free |issn=1660-3397 |pmc=3131562 |pmid=21747749}} Peridinin is highly efficient in capturing blue light, which penetrates deeper into the water column, giving many dinoflagellates a competitive advantage in stratified or turbid environments.{{Cite journal |last1=Jiang |first1=Jing |last2=Zhang |first2=Hao |last3=Kang |first3=Yisheng |last4=Bina |first4=David |last5=Lo |first5=Cynthia S. |last6=Blankenship |first6=Robert E. |date=July 2012 |title=Characterization of the peridinin-chlorophyll a-protein complex in the dinoflagellate Symbiodinium |journal=Biochimica et Biophysica Acta (BBA) - Bioenergetics |volume=1817 |issue=7 |pages=983–989 |doi=10.1016/j.bbabio.2012.03.027 |issn=0006-3002 |pmc=3947849 |pmid=22497797}} Additionally, dinoflagellates contain other carotenoids such as diadinoxanthin and dinoxanthin, which play important roles in photoprotection by dissipating excess light energy and preventing oxidative stress under high irradiance.{{Cite journal |last1=Lavaud |first1=Johann |last2=Rousseau |first2=Bernard |last3=van Gorkom |first3=Hans J. |last4=Etienne |first4=Anne-Lise |date=2002-07-01 |title=Influence of the Diadinoxanthin Pool Size on Photoprotection in the Marine Planktonic Diatom Phaeodactylum tricornutum |journal=Plant Physiology |language=en |volume=129 |issue=3 |pages=1398–1406 |doi=10.1104/pp.002014 |pmid=12114593 |pmc=166533 |issn=1532-2548 }} These pigments are necessary for photoacclimation, allowing dinoflagellates to survive under fluctuating light conditions.

Not all dinoflagellates rely solely on photosynthetic pigments for energy. Many species are heterotrophic or mixotrophic, meaning they can acquire nutrients through both photosynthesis and predation.{{Cite web |title=Acquired phototrophy in aquatic protists |url=https://www.researchgate.net/publication/242489569 |archive-url=https://web.archive.org/web/20180701083507/https://www.researchgate.net/publication/242489569_Acquired_phototrophy_in_aquatic_protists |archive-date=2018-07-01 |access-date=2025-02-16 |website=ResearchGate |language=en |url-status=live }} Symbiotic dinoflagellates, such as Symbiodinium, play a important ecological role by forming mutualistic relationships with corals, where their pigments drive photosynthesis and energy production that sustain coral reef ecosystems.{{Cite journal |last1=Stat |first1=Michael |last2=Carter |first2=Dee |last3=Hoegh-Guldberg |first3=Ove |date=2006-09-27 |title=The evolutionary history of Symbiodinium and scleractinian hosts—Symbiosis, diversity, and the effect of climate change |url=https://www.sciencedirect.com/science/article/abs/pii/S1433831906000035 |journal=Perspectives in Plant Ecology, Evolution and Systematics |volume=8 |issue=1 |pages=23–43 |doi=10.1016/j.ppees.2006.04.001 |bibcode=2006PPEES...8...23S |issn=1433-8319|url-access=subscription }} The unique pigment composition of dinoflagellates also contributes to large-scale phenomena such as harmful algal blooms and red tides, where high concentrations of pigmented cells cause dramatic discoloration of coastal waters and can produce toxic effects.{{Cite journal |last1=Anderson |first1=Donald M. |last2=Cembella |first2=Allan D. |last3=Hallegraeff |first3=Gustaaf M. |date=2012 |title=Progress in understanding harmful algal blooms: paradigm shifts and new technologies for research, monitoring, and management |journal=Annual Review of Marine Science |volume=4 |pages=143–176 |doi=10.1146/annurev-marine-120308-081121 |issn=1941-1405 |pmc=5373096 |pmid=22457972|bibcode=2012ARMS....4..143A }}

Dinoflagellate blooms are generally unpredictable, short, with low species diversity, and with little species succession.{{cite journal |last1=Smayda |first1=Theodore J. |author-link=Theodore J. Smayda |title=Adaptive ecology, growth strategies and the global bloom expansion of dinoflagellates |journal=Journal of Oceanography |volume=58 |issue=2 |year=2002 |pages=281–294 |issn=0916-8370 |doi=10.1023/A:1015861725470 |bibcode=2002JOce...58..281S |s2cid=55024118}} The low species diversity can be due to multiple factors. One way a lack of diversity may occur in a bloom is through a reduction in predation and a decreased competition. The first may be achieved by having predators reject the dinoflagellate, by, for example, decreasing the amount of food it can eat. This additionally helps prevent a future increase in predation pressure by causing predators that reject it to lack the energy to breed. A species can then inhibit the growth of its competitors, thus achieving dominance.{{cite journal| vauthors = Huntley M, Sykes P, Rohan S, Marin V |title=Chemically-mediated rejection of dinoflagellate prey by the copepods Calanus pacificus and Paracalanus parvus: mechanism, occurrence and significance |journal=Marine Ecology Progress Series |year=1986 |volume=28 |pages=105–120|doi=10.3354/meps028105 |bibcode=1986MEPS...28..105H |doi-access=free }}

{{Main|Harmful algal bloom}}

Dinoflagellates sometimes bloom in concentrations of more than a million cells per millilitre. Under such circumstances, they can produce toxins (generally called dinotoxins) in quantities capable of killing fish and accumulating in filter feeders such as shellfish, which in turn may be passed on to people who eat them. This phenomenon is called a red tide, from the color the bloom imparts to the water. Some colorless dinoflagellates may also form toxic blooms, such as Pfiesteria. Some dinoflagellate blooms are not dangerous. Bluish flickers visible in ocean water at night often come from blooms of bioluminescent dinoflagellates, which emit short flashes of light when disturbed.

File:Algal bloom(akasio) by Noctiluca in Nagasaki.jpg

A red tide occurs because dinoflagellates are able to reproduce rapidly and copiously as a result of the abundant nutrients in the water. They contain toxins that affect surrounding marine life and people who consume them.{{cite book | last = Faust | first = M.A. | author2 = Gulledge, R.A. | title = Identifying Harmful Marine Dinoflagellates | publisher = Department of Systematic Biology, Botany, National Museum of Natural History | location = Washington, D.C. | year = 2002 | issn = 0097-1618 | series = Contributions from the United States National Herbarium | volume = 42 | url = http://www.nmnh.si.edu/botany/projects/dinoflag/ | access-date = 2007-05-18 | archive-url = https://web.archive.org/web/20070430225920/http://www.nmnh.si.edu/botany/projects/dinoflag/ | archive-date = 2007-04-30 }} A specific carrier is shellfish, which can introduce both nonfatal and fatal illnesses. One such poison is saxitoxin, a powerful paralytic neurotoxin.{{cite journal | vauthors = Lin S, Litaker RW, Sunda WG | title = Phosphorus physiological ecology and molecular mechanisms in marine phytoplankton | journal = Journal of Phycology | volume = 52 | issue = 1 | pages = 10–36 | date = February 2016 | pmid = 26987085 | doi = 10.1111/jpy.12365 | s2cid = 206147416 | bibcode = 2016JPcgy..52...10L }}{{cite journal | vauthors = Zhang C, Luo H, Huang L, Lin S | title = Molecular mechanism of glucose-6-phosphate utilization in the dinoflagellate Karenia mikimotoi | journal = Harmful Algae | volume = 67 | pages = 74–84 | date = July 2017 | pmid = 28755722 | doi = 10.1016/j.hal.2017.06.006 | bibcode = 2017HAlga..67...74Z }}{{cite journal | vauthors = Luo H, Lin X, Li L, Lin L, Zhang C, Lin S | title = Transcriptomic and physiological analyses of the dinoflagellate Karenia mikimotoi reveal non-alkaline phosphatase-based molecular machinery of ATP utilisation | journal = Environmental Microbiology | volume = 19 | issue = 11 | pages = 4506–4518 | date = November 2017 | pmid = 28856827 | doi = 10.1111/1462-2920.13899 | s2cid = 3598741 | doi-access = free | bibcode = 2017EnvMi..19.4506L }}

Human inputs of phosphate further encourage these red tides, so strong interest exists in learning more about dinoflagellates, from both medical and economic perspectives. Dinoflagellates are known to be particularly capable of scavenging dissolved organic phosphorus for P-nutrient, several HAS species have been found to be highly versatile and mechanistically diversified in utilizing different types of DOPs. The ecology of harmful algal blooms is extensively studied.{{cite book |vauthors=Granéli E, Turner JT |title=Ecology of Harmful Algae |series=Ecological Studies: Analysis and Synthesis |url=https://books.google.com/books?id=-707tqiXoZUC |year=2007 |publisher=Springer |isbn=978-3-5407-4009-4 |volume=189 |issn=0070-8356 |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707091756/http://books.google.com/books?id=-707tqiXoZUC |url-status=live }}

File:Noctiluca scintillans.jpg, Belgium]]

File:Kayaking in the Bioluminescent Bay Vieques.webm, Vieques, Puerto Rico]]

At night, water can have an appearance of sparkling light due to the bioluminescence of dinoflagellates.{{cite book |last1=Castro |first1=Peter |first2=Michael E. |last2=Huber |title=Marine Biology |publisher=McGraw Hill |year=2010 |isbn=978-0-0711-1302-1 |pages=95 |edition=8th }}{{cite journal | vauthors = Hastings JW | title = Chemistries and colors of bioluminescent reactions: a review | journal = Gene | volume = 173 | issue = 1 Spec No | pages = 5–11 | year = 1996 | pmid = 8707056 | doi = 10.1016/0378-1119(95)00676-1 }} More than 18 genera of dinoflagellates are bioluminescent,Poupin, J., A.-S. Cussatlegras, and P. Geistdoerfer. 1999. Plancton marin bioluminescent. Rapport scientifique du Laboratoire d'Océanographie de l'École Navale LOEN, Brest, France, 83 pp. and the majority of them emit a blue-green light.{{cite book |last=Sweeney |first=B. |title=Bioluminescence and circadian rhythms}} In: {{harvnb|Taylor|1987|pp=269–281}} These species contain scintillons, individual cytoplasmic bodies (about 0.5 μm in diameter) distributed mainly in the cortical region of the cell, outpockets of the main cell vacuole. They contain dinoflagellate luciferase, the main enzyme involved in dinoflagellate bioluminescence, and luciferin, a chlorophyll-derived tetrapyrrole ring that acts as the substrate to the light-producing reaction. The luminescence occurs as a brief (0.1 sec) blue flash (max 476 nm) when stimulated, usually by mechanical disturbance. Therefore, when mechanically stimulated—by boat, swimming, or waves, for example—a blue sparkling light can be seen emanating from the sea surface.{{cite journal | vauthors = Haddock SH, Moline MA, Case JF | title = Bioluminescence in the sea | journal = Annual Review of Marine Science | volume = 2 | pages = 443–493 | date = 1 October 2009 | pmid = 21141672 | doi = 10.1146/annurev-marine-120308-081028 | s2cid = 3872860 | bibcode = 2010ARMS....2..443H }}

Dinoflagellate bioluminescence is controlled by a circadian clock and only occurs at night.{{cite journal |vauthors=Knaust R, Urbig T, Li L, Taylor W, Hastings JW |title=The circadian rhythm of bioluminescence in Pyrocystis is not due to differences in the amount of luciferase: a comparative study of three bioluminescent marine dinoflagellates |journal=J. Phycol. |volume=34 |issue=1 |pages=167–172 |date=February 1998 |doi=10.1046/j.1529-8817.1998.340167.x |bibcode=1998JPcgy..34..167K |s2cid=84990824 }} Luminescent and nonluminescent strains can occur in the same species. The number of scintillons is higher during night than during day, and breaks down during the end of the night, at the time of maximal bioluminescence.{{cite journal | vauthors = Fritz L, Morse D, Hastings JW | title = The circadian bioluminescence rhythm of Gonyaulax is related to daily variations in the number of light-emitting organelles | journal = Journal of Cell Science | volume = 95 | issue = Pt 2 | pages = 321–328 | date = February 1990 | pmid = 2196272 | doi = 10.1242/jcs.95.2.321 }}

The luciferin-luciferase reaction responsible for the bioluminescence is pH sensitive. When the pH drops, luciferase changes its shape, allowing luciferin, more specifically tetrapyrrole, to bind. Dinoflagellates can use bioluminescence as a defense mechanism. They can startle their predators by their flashing light or they can ward off potential predators by an indirect effect such as the "burglar alarm". The bioluminescence attracts attention to the dinoflagellate and its attacker, making the predator more vulnerable to predation from higher trophic levels.

Bioluminescent dinoflagellate ecosystem bays are among the rarest and most fragile,{{cite journal |author=Dybas CL |title=Bright Microbes—Scientists uncover new clues to bioluminescence |journal=Scientific American |volume=360 |issue=5 |pages=19 |date=May 2012 |doi=10.1038/scientificamerican0512-19 |bibcode=2012SciAm.306e..19D }} with the most famous ones being the Bioluminescent Bay in La Parguera, Lajas, Puerto Rico; Mosquito Bay in Vieques, Puerto Rico; and Las Cabezas de San Juan Reserva Natural Fajardo, Puerto Rico. Also, a bioluminescent lagoon is near Montego Bay, Jamaica, and bioluminescent harbors surround Castine, Maine.{{cite web |url=http://visitmaine.com/deals/castine-kayak-bioluminescent-bay-night-kayak-excursion/?uid=vtm35E9052A846C4F67E |title=Castine Kayak Bioluminescent Bay Night Kayak Excursion |date=2015 |access-date=1 July 2015 |work=visitmaine.com |author=Castine Kayak |archive-date=2 July 2015 |archive-url=https://web.archive.org/web/20150702065513/http://visitmaine.com/deals/castine-kayak-bioluminescent-bay-night-kayak-excursion/?uid=vtm35E9052A846C4F67E }} Within the United States, Central Florida is home to the Indian River Lagoon which is abundant with dinoflagellates in the summer and bioluminescent ctenophore in the winter.{{cite web |last1=Kennedy Duckett |first1=Maryellen |title=Florida by Water: Experience Bioluminescence |website=National Geographic Society |url=https://www.nationalgeographic.com/travel/florida-land-and-sea/experience-bioluminescence/ |access-date=31 July 2018 |date=2015-02-10 |archive-date=2018-07-31 |archive-url=https://web.archive.org/web/20180731123537/https://www.nationalgeographic.com/travel/florida-land-and-sea/experience-bioluminescence/}}

Dinoflagellates produce characteristic lipids and sterols.{{cite book |last=Withers |first=N. |title=Dinoflagellate sterols}} In: {{harvnb|Taylor|1987|pp=316–359}} One of these sterols is typical of dinoflagellates and is called dinosterol.

Dinoflagellate theca can sink rapidly to the seafloor in marine snow.{{cite journal |vauthors=Alldredge AL, Passow U, Haddock SH |title=The characteristics and transparent exopolymer particle (TEP) content of marine snow formed from thecate dinoflagellates |journal=J. Plankton Res. |volume=20 |issue=3 |pages=393–406 |year=1998 |doi=10.1093/plankt/20.3.393 |doi-access=free }}

Dinoflagellates have a haplontic life cycle, with the possible exception of Noctiluca and its relatives.

The life cycle usually involves asexual reproduction by means of mitosis, either through desmoschisis or eleuteroschisis. More complex life cycles occur, more particularly with parasitic dinoflagellates. Sexual reproduction also occurs,{{cite journal |author=von Stosch HA |title=Observations on vegetative reproduction and sexual life cycles of two freshwater dinoflagellates, Gymnodinium pseudopalustre Schiller and Woloszynskia apiculata sp. nov. |journal=British Phycological Journal |volume=8 |issue=2 |pages=105–34 |year=1973 |doi=10.1080/00071617300650141 |url=http://www.tandfonline.com/toc/tejp19/8/2 |access-date=2014-05-13 |archive-date=2019-02-13 |archive-url=https://web.archive.org/web/20190213005725/https://www.tandfonline.com/toc/tejp19/8/2 |url-status=live |url-access=subscription }} though this mode of reproduction is only known in a small percentage of dinoflagellates.{{cite book |last1=Pfiester |last2=Anderson |chapter=Ch. 14 |editor-last=Taylor |editor-first=F.J.R. |title=The Biology of dinoflagellates |publisher=Blackwell Scientific |year=1987 |isbn=978-0-6320-0915-2 |volume=21 |series=Botanical monographs |chapter-url-access=registration |chapter-url=https://archive.org/details/biologyofdinofla0000unse |url-access=registration |url=https://archive.org/details/biologyofdinofla0000unse }} This takes place by fusion of two individuals to form a zygote, which may remain mobile in typical dinoflagellate fashion and is then called a planozygote. This zygote may later form a resting stage or hypnozygote, which is called a dinoflagellate cyst or dinocyst. After (or before) germination of the cyst, the hatchling undergoes meiosis to produce new haploid cells. Dinoflagellates appear to be capable of carrying out several DNA repair processes that can deal with different types of DNA damage.{{cite journal | vauthors = Li C, Wong JT | title = DNA Damage Response Pathways in Dinoflagellates | journal = Microorganisms | volume = 7 | issue = 7 | page = 191 | date = July 2019 | pmid = 31284474 | pmc = 6680887 | doi = 10.3390/microorganisms7070191 | doi-access = free }}

File:Dinoflagellata Life Cycle.svg

File:Life cycle of dinoflagellates.webp Material was copied from this source, which is available under a [https://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 International License] {{Webarchive|url=https://web.archive.org/web/20110223101209/http://creativecommons.org//licenses//by//3.0// |date=2011-02-23 }}.}}]]

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{{See also|Dinocyst|Resting spore}}

The life cycle of many dinoflagellates includes at least one nonflagellated benthic stage as a cyst. Different types of dinoflagellate cysts are mainly defined based on morphological (number and type of layers in the cell wall) and functional (long- or short-term endurance) differences. These characteristics were initially thought to clearly distinguish pellicle (thin-walled) cysts from resting (double-walled) dinoflagellate cysts. The former were considered short-term (temporal) and the latter long-term (resting) cysts. However, during the last two decades further knowledge has highlighted the great intricacy of dinoflagellate life histories.

File:Resting cysts of dinoflagellates.webp (b), Protoceratium reticulatum (c), A. taylori (d), A. tamarense (e), Protoperidinium oblongum (f), Kryptoperidinium triquetrum (g), and Gymnodinium catenatum (h). Scale bar: 10 μm.]]

More than 10% of the approximately 2000 known marine dinoflagellate species produce cysts as part of their life cycle (see diagram on the right). These benthic phases play an important role in the ecology of the species, as part of a planktonic-benthic link in which the cysts remain in the sediment layer during conditions unfavorable for vegetative growth and, from there, reinoculate the water column when favorable conditions are restored.

Indeed, during dinoflagellate evolution the need to adapt to fluctuating environments and/or to seasonality is thought to have driven the development of this life cycle stage. Most protists form dormant cysts in order to withstand starvation and UV damage.{{cite journal | vauthors = Cavalier-Smith T | title = Origins of the machinery of recombination and sex | journal = Heredity | volume = 88 | issue = 2 | pages = 125–141 | date = February 2002 | pmid = 11932771 | doi = 10.1038/sj.hdy.6800034 | s2cid = 13213957 | doi-access = free }} However, there are enormous differences in the main phenotypic, physiological and resistance properties of each dinoflagellate species cysts. Unlike in higher plants most of this variability, for example in dormancy periods, has not been proven yet to be attributed to latitude adaptation or to depend on other life cycle traits.{{cite journal | vauthors = Wagmann K, Hautekèete NC, Piquot Y, Meunier C, Schmitt SE, Van Dijk H | title = Seed dormancy distribution: explanatory ecological factors | journal = Annals of Botany | volume = 110 | issue = 6 | pages = 1205–1219 | date = November 2012 | pmid = 22952378 | pmc = 3478053 | doi = 10.1093/aob/mcs194 }}{{cite journal | vauthors = Debieu M, Tang C, Stich B, Sikosek T, Effgen S, Josephs E, Schmitt J, Nordborg M, Koornneef M, de Meaux J | title = Co-variation between seed dormancy, growth rate and flowering time changes with latitude in Arabidopsis thaliana | journal = PLOS ONE | volume = 8 | issue = 5 | pages = e61075 | year = 2013 | pmid = 23717385 | pmc = 3662791 | doi = 10.1371/journal.pone.0061075 | doi-access = free | bibcode = 2013PLoSO...861075D }} Thus, despite recent advances in the understanding of the life histories of many dinoflagellate species, including the role of cyst stages, many gaps remain in knowledge about their origin and functionality.

Recognition of the capacity of dinoflagellates to encyst dates back to the early 20th century, in biostratigraphic studies of fossil dinoflagellate cysts. Paul Reinsch was the first to identify cysts as the fossilized remains of dinoflagellates.Reinsch, P.F. (1905) "Die palinosphärien, ein mikroskopischer vegetabile organismus in der mukronatenkreide". ..Cent. Miner. Geol. Palaeontol..., 402–407. Later, cyst formation from gamete fusion was reported, which led to the conclusion that encystment is associated with sexual reproduction. These observations also gave credence to the idea that microalgal encystment is essentially a process whereby zygotes prepare themselves for a dormant period.{{cite book |last1=Loeblich |first1=A.R. |last2=Loeblich |first2=L.A. |chapter=Dinoflagellate cysts |chapter-url={{GBurl|qCcgFximE8oC|p=443}} |editor-last=Spector |editor-first=D.L. |title=Dinoflagellates |publisher=Academic Press |location= |date=2012 |isbn=978-0-323-13813-0 |pages=444–474 |orig-date=1984}} Because the resting cysts studied until that time came from sexual processes, dormancy was associated with sexuality, a presumption that was maintained for many years. This attribution was coincident with evolutionary theories about the origin of eukaryotic cell fusion and sexuality, which postulated advantages for species with diploid resting stages, in their ability to withstand nutrient stress and mutational UV radiation through recombinational repair, and for those with haploid vegetative stages, as asexual division doubles the number of cells. Nonetheless, certain environmental conditions may limit the advantages of recombination and sexuality,{{cite journal | vauthors = Lenormand T, Otto SP | title = The evolution of recombination in a heterogeneous environment | journal = Genetics | volume = 156 | issue = 1 | pages = 423–438 | date = September 2000 | pmid = 10978305 | pmc = 1461255 | doi = 10.1093/genetics/156.1.423 }} such that in fungi, for example, complex combinations of haploid and diploid cycles have evolved that include asexual and sexual resting stages.{{cite journal | vauthors = Lee SC, Ni M, Li W, Shertz C, Heitman J | title = The evolution of sex: a perspective from the fungal kingdom | journal = Microbiology and Molecular Biology Reviews | volume = 74 | issue = 2 | pages = 298–340 | date = June 2010 | pmid = 20508251 | pmc = 2884414 | doi = 10.1128/MMBR.00005-10 }}

However, in the general life cycle of cyst-producing dinoflagellates as outlined in the 1960s and 1970s, resting cysts were assumed to be the fate of sexuality,{{cite journal |doi = 10.1111/j.1529-8817.1978.tb02452.x|title = Potential Importance of Benthic Cysts of Gonyaulax Tamarensis and G. Excavata in Initiating Toxic Dinoflagellate Blooms1, 2, 3|year = 1978|last1 = Anderson|first1 = Donald Mark|last2 = Wall|first2 = David|journal = Journal of Phycology|volume = 14|issue = 2|pages = 224–234| bibcode=1978JPcgy..14..224A |s2cid = 85372383}} which itself was regarded as a response to stress or unfavorable conditions. Sexuality involves the fusion of haploid gametes from motile planktonic vegetative stages to produce diploid planozygotes that eventually form cysts, or hypnozygotes, whose germination is subject to both endogenous and exogenous controls. Endogenously, a species-specific physiological maturation minimum period (dormancy) is mandatory before germination can occur. Thus, hypnozygotes were also referred to as "resting" or "resistant" cysts, in reference to this physiological trait and their capacity following dormancy to remain viable in the sediments for long periods of time. Exogenously, germination is only possible within a window of favorable environmental conditions.

Yet, with the discovery that planozygotes were also able to divide it became apparent that the complexity of dinoflagellate life cycles was greater than originally thought.{{cite journal |doi = 10.2331/suisan.57.2249|title = Life-Cycle and Its Control of Sargassum muticum (Phaeophyta) in Batch Cultures|year = 1991|last1 = Uchida|first1 = Takuji|last2 = Yoshikawa|first2 = Koji|last3 = Arai|first3 = Akemi|last4 = Arai|first4 = Shogo|journal = Nippon Suisan Gakkaishi|volume = 57|issue = 12|pages = 2249–2253|doi-access = free}}{{cite journal |doi = 10.1111/j.1440-1835.1996.tb00040.x|title = The life cycle of Gyrodinium instriatum (Dinophyceae) in culture|year = 1996|last1 = Uchida|first1 = Takuji|last2 = Matsuyama|first2 = Yukihiko|last3 = Yamaguchi|first3 = Mineo|last4 = Honjo|first4 = Tsuneo|journal = Phycological Research|volume = 44|issue = 3|pages = 119–123|s2cid = 84051080}} Following corroboration of this behavior in several species, the capacity of dinoflagellate sexual phases to restore the vegetative phase, bypassing cyst formation, became well accepted.{{cite journal |doi = 10.1111/j.1529-8817.2005.04150.x|title = Sexual Reproduction and Two Different Encystment Strategies of Lingulodinium Polyedrum (Dinophyceae) in Culture1|year = 2005|last1 = Figueroa|first1 = Rosa Isabel|last2 = Bravo|first2 = Isabel|journal = Journal of Phycology|volume = 41|issue = 2|pages = 370–379| bibcode=2005JPcgy..41..370F | hdl=10508/11133 |s2cid = 85652450|hdl-access = free}}{{cite journal |doi = 10.1111/j.1529-8817.2006.00262.x|title = Multiple Routes of Sexuality in Alexandrium Taylori (Dinophyceae) in Culture|year = 2006|last1 = Figueroa|first1 = Rosa Isabel|last2 = Bravo|first2 = Isabel|last3 = Garcés|first3 = Esther|journal = Journal of Phycology|volume = 42|issue = 5|pages = 1028–1039| bibcode=2006JPcgy..42.1028F |s2cid = 85188678}} Further, in 2006 Kremp and Parrow showed the dormant resting cysts of the Baltic cold water dinoflagellates Scrippsiella hangoei and Gymnodinium sp. were formed by the direct encystment of haploid vegetative cells, i.e., asexually.{{cite journal |doi = 10.1111/j.1529-8817.2006.00205.x|title = Evidence for Asexual Resting Cysts in the Life Cycle of the Marine Peridinoid Dinoflagellate, Scrippsiella Hangoei1|year = 2006|last1 = Kremp|first1 = Anke|last2 = Parrow|first2 = Matthew W.|journal = Journal of Phycology|volume = 42|issue = 2|pages = 400–409| bibcode=2006JPcgy..42..400K |s2cid = 84228384}} In addition, for the zygotic cysts of Pfiesteria piscicida dormancy was not essential.{{cite journal |doi = 10.1111/j.1529-8817.2004.03202.x|title = The Sexual Life Cycles of Pfiesteria Piscicida and Cryptoperidiniopsoids (Dinophyceae)1|year = 2004|last1 = Parrow|first1 = Matthew W.|last2 = Burkholder|first2 = Joann M.|journal = Journal of Phycology|volume = 40|issue = 4|pages = 664–673| bibcode=2004JPcgy..40..664P |s2cid = 83695348}}

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One of the most striking features of dinoflagellates is the large amount of cellular DNA that they contain. Most eukaryotic algae contain on average about 0.54 pg DNA/cell, whereas estimates of dinoflagellate DNA content range from 3–250 pg/cell, corresponding to roughly 3000–215 000 Mb (in comparison, the haploid human genome is 3180 Mb and hexaploid Triticum wheat is 16 000 Mb). Polyploidy or polyteny may account for this large cellular DNA content,{{cite book |first1=Carl A. |last1=Beam |first2=Marion |last2=Himes |title=Ch. 8: Dinoflagellate genetics |url=https://books.google.com/books?id=qCcgFximE8oC&pg=PA263 |pages=263–298 |isbn=978-0-3231-3813-0 |date=2012-12-02 |publisher=Academic Press |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707091932/http://books.google.com/books?id=qCcgFximE8oC&pg=PA263 |url-status=live }} In {{harvnb|Spector|1984}} but earlier studies of DNA reassociation kinetics and recent genome analyses do not support this hypothesis.{{cite journal | vauthors = Lin S, Cheng S, Song B, Zhong X, Lin X, Li W, Li L, Zhang Y, Zhang H, Ji Z, Cai M, Zhuang Y, Shi X, Lin L, Wang L, Wang Z, Liu X, Yu S, Zeng P, Hao H, Zou Q, Chen C, Li Y, Wang Y, Xu C, Meng S, Xu X, Wang J, Yang H, Campbell DA, Sturm NR, Dagenais-Bellefeuille S, Morse D | title = The Symbiodinium kawagutii genome illuminates dinoflagellate gene expression and coral symbiosis | journal = Science | volume = 350 | issue = 6261 | pages = 691–694 | date = November 2015 | pmid = 26542574 | doi = 10.1126/science.aad0408 | doi-access = free | bibcode = 2015Sci...350..691L }} Rather, this has been attributed, hypothetically, to the rampant retroposition found in dinoflagellate genomes.{{cite journal | vauthors = Song B, Morse D, Song Y, Fu Y, Lin X, Wang W, Cheng S, Chen W, Liu X, Lin S | title = Comparative Genomics Reveals Two Major Bouts of Gene Retroposition Coinciding with Crucial Periods of Symbiodinium Evolution | journal = Genome Biology and Evolution | volume = 9 | issue = 8 | pages = 2037–2047 | date = August 2017 | pmid = 28903461 | pmc = 5585692 | doi = 10.1093/gbe/evx144 }}{{cite journal | vauthors = Hou Y, Ji N, Zhang H, Shi X, Han H, Lin S | title = Genome size-dependent pcna gene copy number in dinoflagellates and molecular evidence of retroposition as a major evolutionary mechanism | journal = Journal of Phycology | volume = 55 | issue = 1 | pages = 37–46 | date = February 2019 | pmid = 30468510 | doi = 10.1111/jpy.12815 | doi-access = free | bibcode = 2019JPcgy..55...37H }}

In addition to their disproportionately large genomes, dinoflagellate nuclei are unique in their morphology, regulation, and composition. Their DNA is so tightly packed that exactly how many chromosomes they have is still uncertain.{{cite web |author=University of Queensland |date=13 May 2019 |url= https://www.sciencedaily.com/releases/2019/05/190513100546.htm |title=Understanding relationship break-ups to protect the reef |website=ScienceDaily |access-date=16 May 2019 |archive-date=13 May 2019 |archive-url= https://web.archive.org/web/20190513171043/https://www.sciencedaily.com/releases/2019/05/190513100546.htm |url-status=live}}

The dinoflagellates share an unusual mitochondrial genome organisation with their relatives, the Apicomplexa.{{cite journal | vauthors = Jackson CJ, Gornik SG, Waller RF | title = The mitochondrial genome and transcriptome of the basal dinoflagellate Hematodinium sp.: character evolution within the highly derived mitochondrial genomes of dinoflagellates | journal = Genome Biology and Evolution | volume = 4 | issue = 1 | pages = 59–72 | year = 2012 | pmid = 22113794 | pmc = 3268668 | doi = 10.1093/gbe/evr122 }} Both groups have very reduced mitochondrial genomes (around 6 kilobases (kb) in the Apicomplexa vs ~16kb for human mitochondria). One species, Amoebophrya ceratii, has lost its mitochondrial genome completely, yet still has functional mitochondria.{{cite journal | vauthors = John U, Lu Y, Wohlrab S, Groth M, Janouškovec J, Kohli GS, Mark FC, Bickmeyer U, Farhat S, Felder M, Frickenhaus S, Guillou L, Keeling PJ, Moustafa A, Porcel BM, Valentin K, Glöckner G | title = An aerobic eukaryotic parasite with functional mitochondria that likely lacks a mitochondrial genome | journal = Science Advances | volume = 5 | issue = 4 | pages = eaav1110 | date = April 2019 | pmid = 31032404 | pmc = 6482013 | doi = 10.1126/sciadv.aav1110 | bibcode = 2019SciA....5.1110J }} The genes on the dinoflagellate genomes have undergone a number of reorganisations, including massive genome amplification and recombination which have resulted in multiple copies of each gene and gene fragments linked in numerous combinations. Loss of the standard stop codons, trans-splicing of mRNAs for the mRNA of cox3, and extensive RNA editing recoding of most genes has occurred.{{cite journal | vauthors = Lin S, Zhang H, Spencer DF, Norman JE, Gray MW | title = Widespread and extensive editing of mitochondrial mRNAS in dinoflagellates | journal = Journal of Molecular Biology | volume = 320 | issue = 4 | pages = 727–739 | date = July 2002 | pmid = 12095251 | doi = 10.1016/S0022-2836(02)00468-0 }}{{cite book | vauthors = Lin S, Zhang H, Gray MW | chapter = RNA editing in dinoflagellates and its implications for the evolutionary history of the editing machinery | publisher = Wiley | editor-last = Smith | editor-first = H. | title = RNA and DNA editing: Molecular Mechanisms and Their Integration into Biological Systems | pages = 280–309 | year = 2008 | chapter-url = {{GBurl|DyFZFqG-d0QC|p=280}} | isbn = 978-0-470-26225-2 }} The reasons for this transformation are unknown. In a small group of dinoflagellates, called 'dinotoms' (Durinskia and Kryptoperidinium), the endosymbionts (diatoms) still have mitochondria, making them the only organisms with two evolutionarily distinct mitochondria.{{cite journal | vauthors = Imanian B, Pombert JF, Dorrell RG, Burki F, Keeling PJ | title = Tertiary endosymbiosis in two dinotoms has generated little change in the mitochondrial genomes of their dinoflagellate hosts and diatom endosymbionts | journal = PLOS ONE | volume = 7 | issue = 8 | pages = e43763 | year = 2012 | pmid = 22916303 | pmc = 3423374 | doi = 10.1371/journal.pone.0043763 | bibcode = 2012PLoSO...743763I | doi-access = free }}

In most of the species, the plastid genome consist of just 14 genes.{{cite journal|title=Marine parasite survives without key genes|journal = Nature Middle East|doi=10.1038/nmiddleeast.2019.63|year = 2019|last1 = Das|first1 = Biplab|s2cid = 149458671}}

The DNA of the plastid in the peridinin-containing dinoflagellates is contained in a series of small circles called minicircles.{{cite journal | vauthors = Laatsch T, Zauner S, Stoebe-Maier B, Kowallik KV, Maier UG | title = Plastid-derived single gene minicircles of the dinoflagellate Ceratium horridum are localized in the nucleus | journal = Molecular Biology and Evolution | volume = 21 | issue = 7 | pages = 1318–1322 | date = July 2004 | pmid = 15034134 | doi = 10.1093/molbev/msh127 | doi-access = free }} Each circle contains one or two polypeptide genes. The genes for these polypeptides are chloroplast-specific because their homologs from other photosynthetic eukaryotes are exclusively encoded in the chloroplast genome. Within each circle is a distinguishable 'core' region. Genes are always in the same orientation with respect to this core region.

In terms of DNA barcoding, ITS sequences can be used to identify species,{{cite journal | vauthors = Stern RF, Andersen RA, Jameson I, Küpper FC, Coffroth MA, Vaulot D, Le Gall F, Véron B, Brand JJ, Skelton H, Kasai F, Lilly EL, Keeling PJ | title = Evaluating the ribosomal internal transcribed spacer (ITS) as a candidate dinoflagellate barcode marker | journal = PLOS ONE | volume = 7 | issue = 8 | pages = e42780 | year = 2012 | pmid = 22916158 | pmc = 3420951 | doi = 10.1371/journal.pone.0042780 | doi-access = free | bibcode = 2012PLoSO...742780S | author-link5 = Mary Alice Coffroth }} where a genetic distance of p≥0.04 can be used to delimit species,{{cite journal |vauthors=Litaker RW, Vandersea MW, Kibler SR, Reece KS, Stokes NA, Lutzoni FM, Yonish BA, West MA, Black MN, Tester PA |title=Recognizing dinoflagellate species using ITS rDNA sequences |journal=J. Phycol. |volume=43 |issue= 2|pages=344–355 |date=April 2007 |doi=10.1111/j.1529-8817.2007.00320.x |bibcode=2007JPcgy..43..344W |s2cid=85929661 }} which has been successfully applied to resolve long-standing taxonomic confusion as in the case of resolving the Alexandrium tamarense complex into five species.{{cite journal | vauthors = Wang L, Zhuang Y, Zhang H, Lin X, Lin S | title = DNA barcoding species in Alexandrium tamarense complex using ITS and proposing designation of five species | journal = Harmful Algae | volume = 31 | pages = 100–113 | date = January 2014 | pmid = 28040099 | doi = 10.1016/j.hal.2013.10.013 | bibcode = 2014HAlga..31..100W }} A recent study{{cite journal | vauthors = Stephens TG, Ragan MA, Bhattacharya D, Chan CX | title = Core genes in diverse dinoflagellate lineages include a wealth of conserved dark genes with unknown functions | journal = Scientific Reports | volume = 8 | issue = 1 | pages = 17175 | date = November 2018 | pmid = 30464192 | pmc = 6249206 | doi = 10.1038/s41598-018-35620-z | ref = Stephens2018 | bibcode = 2018NatSR...817175S }} revealed a substantial proportion of dinoflagellate genes encode for unknown functions, and that these genes could be conserved and lineage-specific.

Dinoflagellates are mainly represented as fossils by dinocysts, which have a long geological record with lowest occurrences during the mid-Triassic,{{cite journal |vauthors=MacRae RA, Fensome RA, Williams GL |title=Fossil dinoflagellate diversity, originations, and extinctions and their significance |journal=Can. J. Bot. |volume=74 |issue= 11|pages=1687–94 |year=1996 |issn=0008-4026 |doi=10.1139/b96-205 |bibcode=1996CaJB...74.1687M }} whilst geochemical markers suggest a presence to the Early Cambrian.{{cite journal | vauthors = Moldowan JM, Talyzina NM | title = Biogeochemical evidence for dinoflagellate ancestors in the early cambrian | journal = Science | volume = 281 | issue = 5380 | pages = 1168–1170 | date = August 1998 | pmid = 9712575 | doi = 10.1126/science.281.5380.1168 | bibcode = 1998Sci...281.1168M }} Some evidence indicates dinosteroids in many Paleozoic and Precambrian rocks might be the product of ancestral dinoflagellates (protodinoflagellates).{{cite journal |vauthors=Moldowan JM, Dahl JE, Jacobson SR, Huizinga BJ, Fago FJ, Shetty R, Watt DS, Peters KE |date=February 1996 |title=Chemostratigraphic reconstruction of biofacies: molecular evidence linking cyst-forming dinoflagellates with Pre-Triassic ancestors |journal=Geology |volume=24 |issue=2 |pages=159–162 |bibcode=1996Geo....24..159M |doi=10.1130/0091-7613(1996)024<0159:CROBME>2.3.CO;2}}{{cite journal |vauthors=Talyzina NM, Moldowan JM, Johannisson A, Fago FJ |date=January 2000 |title=Affinities of early Cambrian acritarchs studied by using microscopy, fluorescence flow cytometry and biomarkers |journal=Rev. Palaeobot. Palynol. |volume=108 |issue=1–2 |pages=37–53 |doi=10.1016/S0034-6667(99)00032-9|bibcode=2000RPaPa.108...37T }} Dinoflagellates show a classic radiation of morphologies during the Late Triassic through the Middle Jurassic.{{Cite journal |last1=Fensome |first1=R. A. |last2=MacRae |first2=R. A. |last3=Moldowan |first3=J. M. |last4=Taylor |first4=F. J. R. |last5=Williams |first5=G. L. |date=1996 |title=The Early Mesozoic Radiation of Dinoflagellates |journal=Paleobiology |volume=22 |issue=3 |pages=329–338 |doi=10.1017/S0094837300016316 |jstor=2401092 |bibcode=1996Pbio...22..329F |s2cid=133043109 |issn=0094-8373}}{{cite journal | vauthors = Chacón J, Gottschling M | title = Dawn of the dinophytes: A first attempt to date origin and diversification of harmful algae | journal = Harmful Algae | volume = 97 | pages = 101871 | date = July 2020 | pmid = 32732051 | doi = 10.1016/j.hal.2020.101871 | s2cid = 220891202 | bibcode = 2020HAlga..9701871C }} More modern-looking forms proliferate during the later Jurassic and Cretaceous.{{Cite web |last=Fensome |first=Robert |date=8 June 2022 |title=Dinoflagellates |url=https://palynology.org/what-is-palynology/palynomorphs/dinoflagellates/?preview_id=40&preview_nonce=48130c1f50&_thumbnail_id=-1&preview=true |website=AASP-The Palynological Society }}{{Dead link|date=October 2023 |bot=InternetArchiveBot |fix-attempted=yes }} This trend continues into the Cenozoic, albeit with some loss of diversity.

Molecular phylogenetics show that dinoflagellates are grouped with ciliates and apicomplexans (=Sporozoa) in a well-supported clade, the alveolates. The closest relatives to dinokaryotic dinoflagellates appear to be apicomplexans, Perkinsus, Parvilucifera, syndinians, and Oxyrrhis.{{cite journal |author1=Saldarriaga J |author2=Taylor MFJR |author3=Cavalier-Smith T |author4=Menden-Deuer S |author-link4=Susanne Menden-Deuer|author5=Keeling PJ |title=Molecular data and the evolutionary history of dinoflagellates |journal=Eur J Protistol |volume=40 |issue=1 |pages=85–111 |year=2004 |doi=10.1016/j.ejop.2003.11.003 |hdl=2429/16056 |hdl-access=free }} Molecular phylogenies are similar to phylogenies based on morphology.{{cite journal |vauthors=Fensome RA, Saldarriaga JF, Taylor FJ |title=Dinoflagellate phylogeny revisited: reconciling morphological and molecular based phylogenies |journal=Grana |volume=38 |issue=2–3 |pages=66–80 |year=1999 |doi=10.1080/00173139908559216 |doi-access=free |bibcode=1999Grana..38...66F }}{{cite journal |vauthors=Gottschling M, Chacón J, Žerdoner Čalasan A, Neuhaus S, Kretschmann J, Stibor H, John U |title=Phylogenetic placement of environmental sequences using taxonomically reliable databases helps to rigorously assess dinophyte biodiversity in Bavarian lakes (Germany) |journal=Freshwater Biology |volume=65 |pages=193–208 |year=2020 |issue=2 |doi=10.1111/fwb.13413 |doi-access=free|bibcode=2020FrBio..65..193G }}

The earliest stages of dinoflagellate evolution appear to be dominated by parasitic lineages, such as perkinsids and syndinians (e.g. Amoebophrya and Hematodinium).{{cite journal | vauthors = Gunderson JH, Goss SH, Coats DW | title = The phylogenetic position of Amoebophrya sp. infecting Gymnodinium sanguineum | journal = The Journal of Eukaryotic Microbiology | volume = 46 | issue = 2 | pages = 194–197 | year = 1999 | pmid = 10361739 | doi = 10.1111/j.1550-7408.1999.tb04603.x | s2cid = 7836479 }}
{{cite journal | vauthors = Gunderson JH, John SA, Boman WC, Coats DW | title = Multiple strains of the parasitic dinoflagellate Amoebophrya exist in Chesapeake Bay | journal = The Journal of Eukaryotic Microbiology | volume = 49 | issue = 6 | pages = 469–474 | year = 2002 | pmid = 12503682 | doi = 10.1111/j.1550-7408.2002.tb00230.x | s2cid = 30051291 }}{{cite journal | vauthors = López-García P, Rodríguez-Valera F, Pedrós-Alió C, Moreira D | title = Unexpected diversity of small eukaryotes in deep-sea Antarctic plankton | journal = Nature | volume = 409 | issue = 6820 | pages = 603–607 | date = February 2001 | pmid = 11214316 | doi = 10.1038/35054537 | s2cid = 11550698 | bibcode = 2001Natur.409..603L }}{{cite journal | vauthors = Moon-van der Staay SY, De Wachter R, Vaulot D | title = Oceanic 18S rDNA sequences from picoplankton reveal unsuspected eukaryotic diversity | journal = Nature | volume = 409 | issue = 6820 | pages = 607–610 | date = February 2001 | pmid = 11214317 | doi = 10.1038/35054541 | s2cid = 4362835 | bibcode = 2001Natur.409..607M }}{{cite journal | vauthors = Saldarriaga JF, Taylor FJ, Keeling PJ, Cavalier-Smith T | title = Dinoflagellate nuclear SSU rRNA phylogeny suggests multiple plastid losses and replacements | journal = Journal of Molecular Evolution | volume = 53 | issue = 3 | pages = 204–213 | date = September 2001 | pmid = 11523007 | doi = 10.1007/s002390010210 | s2cid = 28522930 | bibcode = 2001JMolE..53..204S }}

All dinoflagellates contain red algal plastids or remnant (nonphotosynthetic) organelles of red algal origin.{{cite journal | vauthors = Janouskovec J, Horák A, Oborník M, Lukes J, Keeling PJ | title = A common red algal origin of the apicomplexan, dinoflagellate, and heterokont plastids | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 107 | issue = 24 | pages = 10949–10954 | date = June 2010 | pmid = 20534454 | pmc = 2890776 | doi = 10.1073/pnas.1003335107 | doi-access = free | bibcode = 2010PNAS..10710949J }} The parasitic dinoflagellate Hematodinium however lacks a plastid entirely.{{cite journal | vauthors = Gornik SG, Cassin AM, MacRae JI, Ramaprasad A, Rchiad Z, McConville MJ, Bacic A, McFadden GI, Pain A, Waller RF | title = Endosymbiosis undone by stepwise elimination of the plastid in a parasitic dinoflagellate | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 112 | issue = 18 | pages = 5767–5772 | date = May 2015 | pmid = 25902514 | pmc = 4426444 | doi = 10.1073/pnas.1423400112 | doi-access = free | bibcode = 2015PNAS..112.5767G }} Some groups that have lost the photosynthetic properties of their original red algae plastids has obtained new photosynthetic plastids (chloroplasts) through so-called serial endosymbiosis, both secondary and tertiary:

• Lepidodinium unusually possesses a green algae-derived plastid (all other serially-acquired plastids can be traced back to red algae).{{cite journal | vauthors = Dorrell RG, Howe CJ | title = Integration of plastids with their hosts: Lessons learned from dinoflagellates | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 112 | issue = 33 | pages = 10247–10254 | date = August 2015 | pmid = 25995366 | pmc = 4547248 | doi = 10.1073/pnas.1421380112 | doi-access = free | bibcode = 2015PNAS..11210247D }} The plastid is most related to free-living Pedinomonas (hence likely secondary). Two previously undescribed dinoflagellates ("MGD" and "TGD") contain a closely-related plastid.{{cite journal |last1=Sarai |first1=C |last2=Tanifuji |first2=G |last3=Nakayama |first3=T |last4=Kamikawa |first4=R |last5=Takahashi |first5=K |last6=Yazaki |first6=E |last7=Matsuo |first7=E |last8=Miyashita |first8=H |last9=Ishida |first9=KI |last10=Iwataki |first10=M |last11=Inagaki |first11=Y |title=Dinoflagellates with relic endosymbiont nuclei as models for elucidating organellogenesis. |journal=Proceedings of the National Academy of Sciences of the United States of America |date=10 March 2020 |volume=117 |issue=10 |pages=5364–5375 |doi=10.1073/pnas.1911884117 |pmid=32094181 |doi-access=free|pmc=7071878 |bibcode=2020PNAS..117.5364S }}
• Karenia, Karlodinium, and Takayama possess plastids of haptophyte origin, produced in three separate events.{{cite journal |last1=Novák Vanclová |first1=Anna MG |last2=Nef |first2=Charlotte |last3=Füssy |first3=Zoltán |last4=Vancl |first4=Adél |last5=Liu |first5=Fuhai |last6=Bowler |first6=Chris |last7=Dorrell |first7=Richard G |title=New plastids, old proteins: repeated endosymbiotic acquisitions in kareniacean dinoflagellates |journal=EMBO Reports |date=18 March 2024 |volume=25 |issue=4 |pages=1859–1885 |doi=10.1038/s44319-024-00103-y|pmid=38499810 |pmc=11014865 }}
• "Dinotoms" (Durinskia and Kryptoperidinium) have plastids derived from diatoms.{{cite journal | vauthors = Kretschmann J, Žerdoner Čalasan A, Gottschling M | title = Molecular phylogenetics of dinophytes harboring diatoms as endosymbionts (Kryptoperidiniaceae, Peridiniales), with evolutionary interpretations and a focus on the identity of Durinskia oculata from Prague | journal = Molecular Phylogenetics and Evolution | volume = 118 | pages = 392–402 | date = January 2018 | pmid = 29066288 | doi = 10.1016/j.ympev.2017.10.011 | bibcode = 2018MolPE.118..392K }}{{cite journal | vauthors = Imanian B, Keeling PJ | title = The dinoflagellates Durinskia baltica and Kryptoperidinium foliaceum retain functionally overlapping mitochondria from two evolutionarily distinct lineages | journal = BMC Evolutionary Biology | volume = 7 | issue = 1 | pages = 172 | date = September 2007 | pmid = 17892581 | pmc = 2096628 | doi = 10.1186/1471-2148-7-172 | doi-access = free | bibcode = 2007BMCEE...7..172I }}.

Some species also perform kleptoplasty:

• Dinophysis have plastids from a cryptomonad, due to kleptoplasty from a cilate prey.Kim, M., Nam, S. W., Shin, W., Coats, D. W. and Park, M. G. 2012: Dinophysis caudata (Dinophyceae) sequesters and retains plastids from the mixotrophic ciliate prey Mesodinium Rubrum. Journal of Phycology, 48: 569-579. doi:10.1111/j.1529-8817.2012.01150.x
• The Kareniaceae (which contains the three haptophyte-having genera) contains two separate cases of kleptoplasty.{{cite journal | vauthors = Gast RJ, Moran DM, Dennett MR, Caron DA | title = Kleptoplasty in an Antarctic dinoflagellate: caught in evolutionary transition? | journal = Environmental Microbiology | volume = 9 | issue = 1 | pages = 39–45 | date = January 2007 | pmid = 17227410 | doi = 10.1111/j.1462-2920.2006.01109.x | bibcode = 2007EnvMi...9...39G }}

Dinoflagellate evolution has been summarized into five principal organizational types: prorocentroid, dinophysoid, gonyaulacoid, peridinioid, and gymnodinoid.{{cite journal | vauthors = Taylor FJ | title = On dinoflagellate evolution | journal = Bio Systems | volume = 13 | issue = 1–2 | pages = 65–108 | year = 1980 | pmid = 7002229 | doi = 10.1016/0303-2647(80)90006-4 | bibcode = 1980BiSys..13...65T }}

The transitions of marine species into fresh water have been frequent events during the diversification of dinoflagellates and have occurred recently.{{cite journal | vauthors = Žerdoner Čalasan A, Kretschmann J, Gottschling M | title = They are young, and they are many: dating freshwater lineages in unicellular dinophytes | journal = Environmental Microbiology | volume = 21 | issue = 11 | pages = 4125–4135 | date = November 2019 | pmid = 31369197 | doi = 10.1111/1462-2920.14766 | doi-access = free | bibcode = 2019EnvMi..21.4125Z }}

Many dinoflagellates also have a symbiotic relationship with cyanobacteria, called cyanobionts, which have a reduced genome and has not been found outside their hosts. The Dinophysoid dinoflagellates have two genera, Amphisolenia and Triposolenia, that contain intracellular cyanobionts, and four genera; Citharistes, Histioneis, Parahistioneis, and Ornithocercus, that contain extracellular cyanobionts.{{cite journal | vauthors = Kim M, Choi DH, Park MG | title = Cyanobiont genetic diversity and host specificity of cyanobiont-bearing dinoflagellate Ornithocercus in temperate coastal waters | journal = Scientific Reports | volume = 11 | issue = 1 | pages = 9458 | date = May 2021 | pmid = 33947914 | pmc = 8097063 | doi = 10.1038/s41598-021-89072-z | bibcode = 2021NatSR..11.9458K }} Most of the cyanobionts are used for nitrogen fixation, not for photosynthesis, but some don't have the ability to fix nitrogen. The dinoflagellate Ornithocercus magnificus is host for symbionts which resides in an extracellular chamber. While it is not fully known how the dinoflagellate benefit from it, it has been suggested it is farming the cyanobacteria in specialized chambers and regularly digest some of them.{{cite journal | vauthors = Nakayama T, Nomura M, Takano Y, Tanifuji G, Shiba K, Inaba K, Inagaki Y, Kawata M | title = Single-cell genomics unveiled a cryptic cyanobacterial lineage with a worldwide distribution hidden by a dinoflagellate host | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 116 | issue = 32 | pages = 15973–15978 | date = August 2019 | pmid = 31235587 | pmc = 6689939 | doi = 10.1073/pnas.1902538116 | doi-access = free | bibcode = 2019PNAS..11615973N }}

Recently, the living fossil Dapsilidinium pastielsii was found inhabiting the Indo-Pacific Warm Pool, which served as a refugium for thermophilic dinoflagellates,{{cite journal |vauthors=Mertens KN, Takano Y, Head MJ, Matsuoka K |title=Living fossils in the Indo-Pacific warm pool: A refuge for thermophilic dinoflagellates during glaciations |journal=Geology |volume=42 |issue=6 |pages=531–534 |year=2014 |doi=10.1130/G35456.1 |bibcode=2014Geo....42..531M }} and others such as Calciodinellum operosum and Posoniella tricarinelloides were also described from fossils before later being found alive.{{cite journal |last1=Montresor |first1=M. |last2=Janofske |first2=D. |last3=Willems |first3=H. |year=1997 |title=The cyst-theca relationship in Calciodinellum operosum emend. (Peridiniales, Dinophyceae) and a new approach for the study of calcareous cysts |journal=Journal of Phycology |volume=33 |issue=1 |pages=122–131 |doi=10.1111/j.0022-3646.1997.00122.x|bibcode=1997JPcgy..33..122M |s2cid=84169394 }}{{cite journal | vauthors = Gu H, Kirsch M, Zinssmeister C, Soehner S, Meier KJ, Liu T, Gottschling M | title = Waking the dead: morphological and molecular characterization of extant †Posoniella tricarinelloides (Thoracosphaeraceae, Dinophyceae) | journal = Protist | volume = 164 | issue = 5 | pages = 583–597 | date = September 2013 | pmid = 23850812 | doi = 10.1016/j.protis.2013.06.001 }}

• Alexandrium
• Gonyaulax
• Gymnodinium
• Lingulodinium polyedrum

Image:Oxyrrhis marina.jpg|Oxyrrhis marina (Oxyrrhea)

Dinophysis acuminata.jpg|Dinophysis acuminata (Dinophyceae)

Image:Ceratium sp umitunoobimusi.jpg|Ceratium macroceros (Dinophyceae)

Image:Ceratium furca.jpg|Ceratium furcoides (Dinophyceae)

File:Dinoflagellate - SEM MUSE.tif|Unknown dinoflagellate under SEM (Dinophyceae)

Image:Pfiesteria shumwayae.jpg|Pfiesteria shumwayae (Dinophyceae)

File:Symbiodinium.png|Symbiodinium sp. (Dinophyceae): zooxanthella, a coral endosymbiont

Image:Noctiluca scintillans varias.jpg|Noctiluca scintillans (Noctiluciphyceae)

• Ciguatera
• Paralytic shellfish poisoning
• Yessotoxin
• Thin layers (oceanography)

{{Reflist}}

{{Refbegin}}

• {{cite book |first=D.L. |last=Spector |title=Dinoflagellates |url=https://books.google.com/books?id=qCcgFximE8oC |year=1984 |publisher=Academic Press |isbn=978-0-3231-3813-0 |access-date=2016-03-05 |archive-date=2014-07-07 |archive-url=https://web.archive.org/web/20140707091545/http://books.google.com/books?id=qCcgFximE8oC |url-status=live }}
• {{cite book |last=Taylor |first=F.J.R. |title=The Biology of Dinoflagellates |publisher=Blackwell Scientific |series=Botanical monographs |year=1987 |isbn=978-0-6320-0915-2 |volume=21 |url-access=registration |url=https://archive.org/details/biologyofdinofla0000unse }}

{{Refend}}

{{Commons category|Dinoflagellata}}

• [http://www.issha.org/ International Society for the Study of Harmful Algae]
• [http://www.obs-vlfr.fr/LOV/aquaparadox/html/ClassicMonographs.php Classic dinoflagellate monographs]
• [http://www.sci.hokudai.ac.jp/~horig/Dinohome/Eng-Doccumentation/Dinophyceae.html Japanese dinoflagellate site] {{Webarchive|url=https://web.archive.org/web/20130512031129/http://www.sci.hokudai.ac.jp/~horig/Dinohome/Eng-Doccumentation/Dinophyceae.html |date=2013-05-12 }}
• [https://web.archive.org/web/20080720134153/http://www.tafi.org.au/zooplankton/imagekey/dinophyta/index.html Noctiluca scintillans—Guide to the Marine Zooplankton of south eastern Australia], [https://web.archive.org/web/20080930064242/http://www.tafi.org.au/ Tasmanian Aquaculture & Fisheries Institute]
• [http://tolweb.org/Dinoflagellates/2445 Tree of Life Dinoflagellates] {{Webarchive|url=https://web.archive.org/web/20121013131322/http://tolweb.org/Dinoflagellates/2445 |date=2012-10-13 }}
• [http://www.dinophyta.org/ Centre of Excellence for Dinophyte Taxonomy CEDiT]
• [http://tolweb.org/Dinoflagellates/2445 Dinoflagellates] {{Webarchive|url=https://web.archive.org/web/20121013131322/http://tolweb.org/Dinoflagellates/2445 |date=2012-10-13 }}
• {{cite news |author=Judson O |author-link=Olivia Judson |title=A Tale of Two Flagella |newspaper=New York Times |date=5 January 2010 |url=http://opinionator.blogs.nytimes.com/2010/01/05/a-tale-of-two-flagella/}}
• {{Citation |last=Tomas |first=Carmelo K. |title=Introduction |date=1997 |work=Identifying Marine Phytoplankton |pages=585–589 |url=https://doi.org/10.1016/b978-012693018-4/50006-9 |access-date=2025-02-16 |publisher=Elsevier |doi=10.1016/b978-012693018-4/50006-9 |isbn=978-0-12-693018-4|url-access=subscription }}

{{Life on Earth}}

{{Eukaryota|D.}}

{{Alveolata}}

{{Plankton}}

{{Taxonbar|from1=Q120490|from2=Q21447509|from3=Q9358965}}

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Category:Endosymbiotic events

Category:Olenekian first appearances

Category:Extant Early Triassic first appearances