Calcareous dinoflagellate cysts or calcareous dinocysts are dinoflagellate cysts produced by a group of peridinoid dinoflagellates, called calcareous dinoflagellates.
Organisms producing calcareous structures are exclusively found in a small group of peridinoid dinoflagellates, called calcareous dinoflagellates. Such calcareous structures are either dinocysts (systematized as Calciodinelloideae [1] ), which are formed during the life cycle (i.e., mostly hypnozygotes, after sexual reproduction, or resting stages; an overview of potential cyst formations is given by [1] ) or found in vegetative stages (namely in Thoracosphaera Kamptner). The potential to produce calcareous structures has been considered as apomorphic within alveolates, [2] arguing for the monophyly of Calciodinellaceae (including Thoracosphaera [3] [4] ).
Calciodinellaceae (Peridiniales, Dinophyceae) comprise 35 extant species of calcareous dinophytes, [5] plus about 260 fossil species. [6] [7] They are distributed in cold through tropical seas of the world (neritic and pelagic). [8] Calcareous cysts are deposited in both marine sediments that are coastal [9] [10] and oceanic. [11] The first freshwater dinoflagellate that produces calcareous cysts was recently discovered. [12]
According to the fossil record, calcareous dinoflagellates originate in the Upper Triassic [4] and are highly diverse during the Cretaceous and throughout the Tertiary. [2] [13] [14]
Due to their long stratigraphic range, many fossil species (namely their cysts) have been described. By contrast, descriptions of extant species are primarily based on the motile stages (namely on the thecae, which are less diverse [13] [15] [16] ). This has led to two distinct systematics: paleontological (with four subordinate groups, primarily based on the cyst wall ultrastructure, of which the c-axes of the crystals are orientated irregularly oblique, regularly radial, regularly tangential, or regularly oblique [2] [13] ) and neontological (with the motile taxa Bysmatrum Faust and Steidinger, Ensiculifera Balech, Pentapharsodinium Indelicato and Loeblich III, and Scrippsiella [17] [18] ).
The dinoflagellates are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey.
A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living fossils commonly are of species-poor lineages, but they need not be. While the body plan of a living fossil remains superficially similar, it is never the same species as the remote relatives it resembles, because genetic drift would inevitably change its chromosomal structure.
Zooxanthellae is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus Symbiodinium, but some are known from the genus Amphidinium, and other taxa, as yet unidentified, may have similar endosymbiont affinities. The true Zooxanthella K.brandt is a mutualist of the radiolarian Collozoum inerme and systematically placed in Peridiniales. Another group of unicellular eukaryotes that partake in similar endosymbiotic relationships in both marine and freshwater habitats are green algae zoochlorellae.
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil.
Gymnodinium is a genus of dinoflagellates, a type of marine and freshwater plankton. It is one of the few naked dinoflagellates, or species lacking armor known as cellulosic plates. Since 2000, the species which had been considered to be part of Gymnodinium have been divided into several genera, based on the nature of the apical groove and partial LSU rDNA sequence data. Amphidinium was redefined later. Gymnodinium belong to red dinoflagellates that, in concentration, can cause red tides. The red tides produced by some Gymnodinium, such as Gymnodinium catenatum, are toxic and pose risks to marine and human life, including paralytic shellfish poisoning.
Dinocysts or dinoflagellate cysts are typically 15 to 100 µm in diameter and produced by around 15–20% of living dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic-walled dinocysts are often resistant and made out of dinosporin. There are also calcareous dinoflagellate cysts and siliceous dinoflagellate cysts.
Bacteriastrum is a genus of diatoms in family Chaetocerotaceae. There are more than 30 described species in genus Bacteriastrum, but many of these are not currently accepted, and new species are still added to the genus. The type species for the genus is Bacteriastrum furcatum Shadbolt.
Alexandrium fundyense is a species of dinoflagellates. It produces toxins that induce paralytic shellfish poisoning (PSP), and is a common cause of red tide. A. fundyense regularly forms massive blooms along the northeastern coasts of the United States and Canada, resulting in enormous economic losses and public health concerns.
Karenia is a genus that consists of unicellular, photosynthetic, planktonic organisms found in marine environments. The genus currently consists of 12 described species. They are best known for their dense toxic algal blooms and red tides that cause considerable ecological and economical damage; some Karenia species cause severe animal mortality. One species, Karenia brevis, is known to cause respiratory distress and neurotoxic shellfish poisoning (NSP) in humans.
Polarella is a dinoflagellate, and is the only extant genus of the Suessiaceae family. The genus was described in 1999 by Marina Montresor, Gabriele Procaccini, and Diane K. Stoecker, and contains only one species, Polarella glacialis. Polarella inhabits channels within ice formations in both the Arctic and Antarctic polar regions, where it plays an important role as a primary producer. Polarella is a thecate dinoflagellate, wherein the cell has an outer covering of cellulose plates, which are arranged in nine latitudinal series. The general morphology of Polarella is similar to that of a typical dinoflagellate. and Polarella has a zygotic life history, wherein it alternates between a motile vegetative phase and a non-motile spiny cyst. While it is thought that the cysts of Polarella have lost their ability to form fossils, the cyst life cycle stage has acted as link to extinct members of the Suessiaceae family.
Lingulodinium polyedra is a species of motile photosynthetic dinoflagellates. L. polyedra are often the cause of red tides in southern California, leading to bioluminescent displays on beaches at night.
Dinosterol is a type of steroid produced by several genera of dinoflagellates. It is a 4α-methyl sterol (4α,23,24-trimethyl-5α-cholest-22E-en-3β-ol), a derivative of dinosterane, rarely found in other classes of protists.
Alexandrium is a genus of dinoflagellates. It contains some of the dinoflagellate species most harmful to humans, because it produces toxic harmful algal blooms (HAB) that cause paralytic shellfish poisoning (PSP) in humans. There are about 30 species of Alexandrium that form a clade, defined primarily on morphological characters in their thecal plates.
Dinosporin is a macromolecular, highly resistant organic compound which forms or partly forms, the enclosing wall of fossilizable organic-walled dinoflagellate cysts.
Polykrikos is one of the genera of family Polykrikaceae that includes athecate pseudocolony-forming dinoflagellates. Polykrikos are characterized by a sophisticated ballistic apparatus, named the nematocyst-taeniocyst complex, which allows species to prey on a variety of organisms. Polykrikos have been found to regulate algal blooms as they feed on toxic dinoflagellates. However, there is also some data available on Polykrikos being toxic to fish.
Durinskia is a genus of dinoflagellate that can be found in freshwater and marine environments. This genus was created to accommodate its type species, Durinskia baltica, after major classification discrepancies were found. While Durinskia species appear to be typical dinoflagellates that are armored with cellulose plates called theca, the presence of a pennate diatom-derived tertiary endosymbiont is their most defining characteristic. This genus is significant to the study of endosymbiotic events and organelle integration since structures and organelle genomes in the tertiary plastids are not reduced. Like some dinoflagellates, species in Durinskia may cause blooms.
Coolia is a marine dinoflagellate genus in the family Ostreopsidaceae. It was first described by Meunier in 1919. There are currently seven identified species distributed globally in tropical and temperate coastal waters. Coolia is a benthic or epiphytic type dinoflagellate: it can be found adhered to sediment or other organisms but it is not limited to these substrates. It can also be found in a freely motile form in the water column. The life cycle of Coolia involves an asexual stage where the cell divides by binary fission and a sexual stage where cysts are produced. Some of the species, for example, Coolia tropicalis and Coolia malayensis, produce toxins that can potentially cause shellfish poisoning in humans.
Haplozoon (/hæploʊ’zoʊən/) are unicellular endo-parasites, primarily infecting maldanid polychaetes. They belong to Dinoflagellata but differ from typical dinoflagellates. Most dinoflagellates are free-living and possess two flagella. Instead, Haplozoon belong to a 5% minority of parasitic dinoflagellates that are not free-living. Additionally, the Haplozoon trophont stage is particularly unique due to an apparent lack of flagella. The presence of flagella or remnant structures is the subject of ongoing research.
Peridiniaceae is a family of dinoflagellates belonging to the order Peridiniales.
Palynodinium is an extinct genus of organic-walled dinoflagellate cyst. It is a fossil species of dinoflagellate cyst used to demarcate the K/Pg boundary, which marks the terminal Cretaceous and the extinction of the dinosaurs. Palynodinium grallator was among the microfossils which lead to the recent discovery of the K/Pg event record in marine sediments of the northeast Pacific.