The dinoflagella are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well; their populations are distributed depending on temperature, salinity, or depth. About half of all dinoflagellates are photosynthetic, and these make up the largest group of eukaryotic algae aside from the diatoms. Being primary producers make them an important part of the aquatic food chain. Some species, called zooxanthellae, are endosymbionts of marine animals and protozoa, and play an important part in the biology of coral reefs. Other dinoflagellates are colorless predators on other protozoa, and a few forms are parasitic (see for example Oodinium, Pfiesteria). Flagellata from Ernst Haeckels Artforms of Nature, 1904 Parasitic excavate (Giardia lamblia) Green alga (Chlamydomonas) Flagellates are cells with one or more whip-like organelles called flagella. ... Typical phyla Chromalveolata Chromista Heterokontophyta Haptophyta Cryptophyta (cryptomonads) Alveolata Dinoflagellata Apicomplexa Ciliophora (ciliates) Cabozoa Excavata Euglenozoa Percolozoa Metamonada Rhizaria Radiolaria Foraminifera Cercozoa Archaeplastida (in part) Rhodophyta (red algae) Glaucophyta (basal archaeplastids) Amoebozoa Choanozoa Many others; classification varies Protists (IPA: (RP); (GenAm)), Greek protiston -a meaning the (most) first of all... Marine is an umbrella term for things relating to the ocean, as with marine biology, marine geology, and as a term for a navy, etc. ... Photomontage of plankton organisms Plankton are any drifting organism that inhabits the water column of oceans, seas, and bodies of fresh water. ... For the village on the Isle of Wight, see Freshwater, Isle of Wight. ... Annual mean sea surface temperature for the World Ocean. ... Annual mean sea surface salinity for the World Ocean. ... The leaf is the primary site of photosynthesis in plants. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative phylogeny Unikonta Opisthokonta Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... Zooxanthellae are golden-brown intracellular endosymbionts of various marine animals and protozoa, especially anthozoans. ... An endosymbiont is any organism that lives within the body or cells of another organism, i. ... Extant Subclasses and Orders Alcyonaria    Alcyonacea    Helioporacea Zoantharia    Antipatharia    Corallimorpharia    Scleractinia    Zoanthidea [1][2]  See Anthozoa for details For other uses, see Coral (disambiguation). ... A parasite is an organism that spends a significant portion of its life in or on the living tissue of a host organism and which causes harm to the host without immediately killing it. ... Species Oodinium limneticum Oodinium pillularis Oodinium pouchetii Oödinium (also known as Piscinoodinium) is a genus of microscopic parasitic dinoflagellates. ... Species Pfiesteria piscicida Pfiesteria shumwayae Pfiesteria is a genus of dinoflagellates. ...

Morphology

Most dinoflagelates are unicellular forms with two dissimilar flagella. One of these extends towards the posterior, called the longitudinal flagellum, while the other forms a lateral circle, called the transverse flagellum. In many forms these are set into grooves, called the sulcus and cingulum. The transverse flagellum provides most of the force propelling the cell, and often imparts to it a distinctive whirling motion, which is what gives the name dinoflagellate refers to (Greek dinos, whirling). The longitudinal acts mainly as the steering wheel, but providing little propulsive force as well.

Dinoflagellates have a complex cell covering called an amphiesma, composed of flattened vesicles, called alveoli. In some forms, these support overlapping cellulose plates that make up a sort of armor called the theca. These come in various shapes and arrangements, depending on the species and sometimes stage of the dinoflagellate. Fibrous extrusomes are also found in many forms. Together with various other structural and genetic details, this organization indicates a close relationship between the dinoflagellates, Apicomplexa, and ciliates, collectively referred to as the alveolates. Species Amphiesma beddomei Amphiesma khasiense Amphiesma modestum Amphiesma monticola Amphiesma nicobariense Amphiesma parallelum Amphiesma pealii Amphiesma platyceps Amphiesma sieboldii Amphiesma stolatum Amphiesma vibakari Amphiesma xenura . ... This article or section is in need of attention from an expert on the subject. ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Extrusomes are membrane-bound structures in some eukaryotes which, under certain conditions, discharge their contents outside the cell. ... Classes & Subclasses Aconoidasida Haemosporasina Piroplasmasina Blastocystea Conoidasida Coccidiasina Gregarinasina The Apicomplexa are a large group of protozoa, characterized by the presence of a unique organelle called an apical complex. ... Classes Karyorelictea Heterotrichea Spirotrichea Litostomatea Phyllopharyngea Nassophorea Colpodea Prostomatea Oligohymenophorea Plagiopylea See text for subclasses. ... The alveolates are a major line of protists. ...

The chloroplasts in most photosynthetic dinoflagellates are bound by three membranes, suggesting they were probably derived from some ingested algae, and contain chlorophylls a and c and either peridinin or fucoxanthin, as well as various other accessory pigments. However, a few have chloroplasts with different pigmentation and structure, some of which retain a nucleus. This suggests that chloroplasts were incorporated by several endosymbiotic events involving already colored or secondarily colorless forms. The discovery of plastids in Apicomplexa have led some to suggest they were inherited from an ancestor common to the two groups, but none of the more basal lines have them. Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that encapsulate the cell. ... Chlorophyll gives leaves their green color Space-filling model of the chlorophyll molecule Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... Natural Ultramarine pigment in powdered form. ... HeLa cells stained for DNA with the Blue Hoechst dye. ...

All the same, the dinoflagellate still 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 light sensitive organelle such as the eyespot or a larger nucleus containing a prominent nucleolus.

Life-cycle

Dinoflagellates have a peculiar form of nucleus, called a dinokaryon, in which the chromosomes are attached to the nuclear membrane. These lack histones and remained condensed throughout interphase rather than just during mitosis, which is closed and involves a unique external spindle. This sort of nucleus was once considered to be an intermediate between the nucleoid region of prokaryotes and the true nuclei of eukaryotes, and so were termed mesokaryotic, but now are considered advanced rather than primitive traits. HeLa cells stained for DNA with the Blue Hoechst dye. ... Figure 1: A representation of a condensed eukaryotic chromosome, as seen during cell division. ... Schematic representation of the assembly of the core histones into the nucleosome. ... Mitosis is the process in which a cell duplicates its chromosomes to generate two identical cells. ... Prokaryotes (pro-KAR-ee-oht) (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative phylogeny Unikonta Opisthokonta Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ...

In most dinoflagellates, the nucleus is dinokaryotic throughout the entire life cycle. They are usually haploid, and reproduce primarily through fission, but sexual reproduction also occurs. This takes place by fusion of two individuals to form a zygote, which may remain mobile in typical dinoflagellate fashion or may form a resting dinocyst, which later undergoes meiosis to produce new haploid cells. Haploid (meaning simple in Greek) cells have only one copy of each chromosome. ... Binary fission Binary fission is the form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size, used by most prokaryotes. ... It has been suggested that Biparental zygote be merged into this article or section. ... Around 10% of living Dinoflagellates produce Dinocysts as a dormant zygotic stage of their lifecycle. ... Not to be confused with miosis. ...

However, when conditions become unfavourable, usually when nutrients become depleted or there is insufficient light, some dinoflagellate species alter their life cycle dramatically. Two vegetative cells will fuse together forming a planozygote. Next, is a stage not much different from hibernation called hypnozygote when the organism takes in excess fat and oil. At the same time its shape is getting fatter and the shell gets harder. Sometimes even spikes are formed. When the weather allows it, these dinoflagellates break out of their shell and are in a temporary stage, planomeiocyte, when they quickly reforms their individual thecae and return to the dinoflagellates at the beginning of the process.

Image of bioluminescent red tide event of 2005 at a beach in Carlsbad California showing brilliantly glowing crashing waves containing billions of Lingulodinium polyedrum dinoflagellates. The phenomenon is thought to have something to do with quorum sensing.

Image File history File links Download high-resolution version (1024x371, 206 KB) Summary Long exposure image of red tide bioluminescence taken at midnight at a Carlsbad, California beach during the 2005 red tide event. ... Image File history File links Download high-resolution version (1024x371, 206 KB) Summary Long exposure image of red tide bioluminescence taken at midnight at a Carlsbad, California beach during the 2005 red tide event. ... A red tide off the coast of La Jolla, California. ... Quorum sensing is the ability of bacteria to communicate and coordinate behavior via signaling molecules. ...

Ecology and fossils

Dinoflagellates sometimes bloom in concentrations of more than a million cells per millilitre. Some species produce neurotoxins, which in such quantities kill fish and accumulate in filter feeders such as shellfish, which in turn may pass them 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. It should be noted that not all dinoflagellate blooms are dangerous. Bluish flickers visible in ocean water at night often come from blooms of bioluminescent dinoflagellates, which emit short flashes of light when disturbed. Algal blooms can present problems for ecosystems and human society An algal bloom is a relatively rapid increase in the population of (usually) phytoplankton algae in an aquatic system. ... A neurotoxin is a toxin that acts specifically on nerve cells – neurons – usually by interacting with membrane proteins such as ion channels. ... Cooked mussels Shellfish is a term used to describe shelled molluscs and crustaceans used as food. ... Algal blooms can present problems for ecosystems and human society An algal bloom is a relatively rapid increase in the population of (usually) phytoplankton algae in an aquatic system. ... Species Pfiesteria piscicida Pfiesteria shumwayae Pfiesteria is a genus of dinoflagellates. ... Bioluminescence is the production and emission of light by a living organism as the result of a chemical reaction during which chemical energy is converted to light energy. ...

Dinoflagellate cysts are found as microfossils from the Triassic period, and form a major part of the organic-walled marine microflora from the middle Jurassic, through the Cretaceous and Cenozoic to the present day. Because some species are adapted to different surface water conditions, these fossils from sediments can be used to reconstruct past surface ocean conditions (Sluijs et al., 2005). Arpylorus, from the Silurian of North Africa was at one time considered to be a dinoflagellate cyst, but this palynomorph is now considered to be part of the microfauna (Arthropoda). It is possible that some of the Paleozoic acritarchs also represent dinoflagellates. The Triassic is a geologic period that extends from about 251 ± 0. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ... The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... The Cenozoic Era (IPA pronunciation: ); sometimes Caenozoic Era or Cainozoic Era (in the United Kingdom), meaning new life (Greek (kainos), new, and (zoe), life), is the most recent of the three classic geological eras. ... The Silurian is a major division of the geologic timescale that extends from the end of the Ordovician period, about 443. ... The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... Acritarchs are small organic structures found as fossils. ...

Cautions

The same Red Tide mentioned above is more specifically produced when dinoflagellates are able to reproduce rapidly and copiously on account of the abundant nutrients in the water. Although the resulting red waves are a miraculous sight, they, again, contain toxins that not only affect all marine life in the ocean but the people who consume them as well. A specific carrier is shellfish. This can introduce both non-fatal and fatal illnesses. Human inputs of phosphate further encourage these red tides, and consequently there is a strong interest in learning more about dinoflagellates, from both medical and economic perspectives. A red tide off the coast of La Jolla, California. ... This article or section does not cite any references or sources. ... Cooked mussels Shellfish is a term used to describe shelled molluscs and crustaceans used as food. ... Above is a ball-and-stick model of the inorganic hydrogenphosphate anion (HPO42−). Colour coding: P (orange); O (red); H (white). ...

Classification

In 1753 the first modern dinoflagellates were described by Baker and named by Muller in 1773. The term derives from the Greek word δεινός (deinos), meaning terrible or formidable and Latin flagrum a diminutive term for a whip or scourge.

These same dinoflagellates were first defined by Otto Bütschli in 1885 as the flagellate order dinoflagellida. Botanists treated them as a division of algae, named Pyrrhophyta ("fire algae"; Greek pyrrhos, fire) after the bioluminscent 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 evolve from non-cyst to cyst forming strategies which makes it nearly impossible to recreate their evolutionary history. Otto Bütschli (1848-1920) was a German zoologist and professor at the University of Heidelberg. ... Typical genera Campylomonas Chilomonas Chroomonas Cryptomonas Falcomonas Geminigera Goniomonas Guillardia Hemiselmis Plagioselmis Proteomonas Storeatula Rhodomonas Teleaulax The cryptomonads are a small group of flagellates, most of which have chloroplasts. ... A protist. ...

See also

• Algal bloom
• Ciguatera
• Paralytic shellfish poisoning (PSP)
• Red tide

Algal blooms can present problems for ecosystems and human society An algal bloom is a relatively rapid increase in the population of (usually) phytoplankton algae in an aquatic system. ... Chemical structure of the ciguatoxin CTX1B Ciguatera is a foodborne illness poisoning in humans caused by eating marine species whose flesh is contaminated with a toxin known as ciguatoxin, which is present in many micro-organisms (particularly, the micro-algae Gambierdiscus toxicus) living in tropical waters. ... 4 distinct shellfish-poisoning syndromes have been identified: Paralytic shellfish poisoning (PSP) Neurologic shellfish poisoning (NSP) Diarrheal shellfish poisoning (DSP) Amnestic shellfish poisoning (ASP) All 4 syndromes share some common features and primarily are associated with bivalve mollusks (eg, mussels, clams, oysters, scallops). ... A red tide off the coast of La Jolla, California. ...

References

• Faust, M.A.; Gulledge, R.A. (2002). Identifying Harmful Marine Dinoflagellates, Contributions from the United States National Herbarium 42. Washington, DC: Department of Systematic Biology, Botany, National Museum of Natural History, 144 p. Retrieved on 2007-05-18. 
• Hoek, C. van den; Mann, D.G. and Jahns, H.M. (1995). Algae : An introduction to phycology. Cambridge, UK: Cambridge University Press, XIV, 623 p. ISBN 0-521-30419-9. 
• Dinoflagellates. MIRACLE. URL accessed on 5 February 2006.
• Sluijs, A.; Pross, J. and Brinkhuis, H. (2005). "From greenhouse to icehouse; organic-walled dinoflagellate cysts as paleoenvironmental indicators in the Paleogene". Earth-Science Reviews 68 (3-4): 281-315. DOI:10.1016/j.earscirev.2004.06.001. ISSN 0012-8252. 
• Rapport, Josh. "Dinoflagellate reproduction." DinoflagellateHabitat, Ecology, and Behavior (05 Jan. 2005). URL accessed on 5 February 2006.