Editing Dinoflagellate (section)

==Ecology and physiology==
===Habitats===
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.

===Endosymbionts===
All [[Zooxanthellae]] are dinoflagellates and most of them are members within Symbiodiniaceae (e.g. the genus ''[[Symbiodinium]]'').<ref>Freudenthal et al. 2007</ref> The association between ''Symbiodinium'' and reef-building [[coral]]s 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]].<ref>{{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 }}</ref> 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.

===Nutritional strategies===
Three nutritional strategies are seen in dinoflagellates: [[phototroph]]y, [[mixotroph]]y, and [[heterotroph]]y. Phototrophs can be [[photoautotroph]]s or [[Auxotrophy|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.<ref>{{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 }}</ref>

{{anchor|peduncle}}Food inclusions contain bacteria, bluegreen algae, diatoms, ciliates, and other dinoflagellates.<ref>{{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 }}</ref><ref name="ReferenceA">{{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 }}</ref><ref>{{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}}
</ref><ref name="ReferenceB">{{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 }}</ref><ref>{{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 }}</ref><ref name="ReferenceC">{{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 }}</ref><ref>{{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 }}</ref>

Mechanisms of capture and ingestion in dinoflagellates are quite diverse. Several dinoflagellates, both thecate (e.g. ''Ceratium hirundinella'',<ref name="ReferenceC"/> ''Peridinium globulus''<ref name="ReferenceB"/>) and nonthecate (e.g. ''Oxyrrhis marina'',<ref name="ReferenceA"/> ''Gymnodinium'' sp.<ref>{{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 }}</ref> and ''Kofoidinium'' spp.<ref>{{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 }}</ref>), 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 [[Extracellular digestion|extracellularly]] (= pallium-feeding).<ref>{{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 }}</ref><ref name="JacAnd">{{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 }}</ref> ''Oblea'', ''Zygabikodinium'', and ''Diplopsalis'' are the only other dinoflagellate genera known to use this particular feeding mechanism.<ref name="JacAnd"/><ref>{{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 }}</ref><ref>{{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 }}</ref>
''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.<ref>{{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 }}</ref> Two related genera, ''Polykrikos'' and ''Neatodinium'', shoot out a harpoon-like organelle to capture prey.<ref>{{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 }}</ref>

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.<ref>{{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 }}</ref> ''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.<ref>{{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 }}</ref>

The feeding mechanisms of the oceanic dinoflagellates remain unknown, although pseudopodial extensions were observed in ''Podolampas bipes''.<ref>{{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 }}</ref>

=== Pigments in dinoflagellates ===
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.<ref>{{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}}</ref> 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.<ref>{{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}}</ref> 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.<ref>{{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}}</ref> 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.<ref>{{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}}</ref> 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.<ref>{{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 }}</ref>  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.<ref>{{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 }}</ref> 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.<ref>{{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}}</ref> 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.<ref>{{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 }}</ref>

===Blooms===
====Introduction====
Dinoflagellate blooms are generally unpredictable, short, with low species diversity, and with little species succession.<ref name="Smayda2002">{{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}}</ref> 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.<ref name="HuntleySykes1986">{{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 }}</ref>

====Harmful algal blooms====
{{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 [[dinotoxin]]s) 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 [[bioluminescence|bioluminescent]] dinoflagellates, which emit short flashes of light when disturbed.
[[File:Algal bloom(akasio) by Noctiluca in Nagasaki.jpg|thumb|Algal bloom (''akasio'') by ''Noctiluca'' spp. in Nagasaki]]
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 [[toxin]]s that affect surrounding marine life and people who consume them.<ref>{{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 }}</ref> A specific carrier is [[shellfish]], which can introduce both nonfatal and fatal illnesses. One such poison is [[saxitoxin]], a powerful [[paralytic]] [[neurotoxin]].<ref name= Lin>{{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 }}</ref><ref name=Zhang>{{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 }}</ref><ref name= Luo>{{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 }}</ref>

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.<ref name= Lin/><ref name=Zhang/><ref name= Luo/> The ecology of [[harmful algal bloom]]s is extensively studied.<ref>{{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 }}</ref>

===Bioluminescence===
[[File:Noctiluca scintillans.jpg|thumb|Long exposure image of bioluminescence of ''N. scintillans'' in the yacht port of [[Zeebrugge]], Belgium]]
[[File:Kayaking in the Bioluminescent Bay Vieques.webm|thumb|thumbtime=55|Kayaking in [[Vieques, Puerto Rico#Bioluminescent Bay|the Bioluminescent Bay]], Vieques, Puerto Rico]]
At night, water can have an appearance of sparkling light due to the bioluminescence of dinoflagellates.<ref>{{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 }}</ref><ref>{{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 }}</ref> More than 18 genera of dinoflagellates are bioluminescent,<ref>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.</ref> and the majority of them emit a blue-green light.<ref>{{cite book |last=Sweeney |first=B. |title=Bioluminescence and circadian rhythms}} In: {{harvnb|Taylor|1987|pp=269–281}}</ref> These species contain [[scintillons]], individual cytoplasmic bodies (about 0.5&nbsp;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&nbsp;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.<ref name="haddock">{{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 }}</ref>

Dinoflagellate bioluminescence is controlled by a circadian clock and only occurs at night.<ref>{{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 }}</ref> 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.<ref>{{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 }}</ref>

The luciferin-luciferase reaction responsible for the bioluminescence is pH sensitive.<ref name="haddock"/> When the pH drops, luciferase changes its shape, allowing luciferin, more specifically tetrapyrrole, to bind.<ref name="haddock"/> 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.<ref name="haddock"/>

Bioluminescent dinoflagellate ecosystem bays are among the rarest and most fragile,<ref>{{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 }}</ref> with the most famous ones being the Bioluminescent Bay in [[Lajas, Puerto Rico|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.<ref>{{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 }}</ref> 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.<ref>{{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/}}</ref>

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

===Transport===

Dinoflagellate [[theca]] can sink rapidly to the seafloor in [[marine snow]].<ref>{{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 }}</ref>