Coolia | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Clade: | Diaphoretickes |
Clade: | SAR |
Clade: | Alveolata |
Phylum: | Myzozoa |
Superclass: | Dinoflagellata |
Class: | Dinophyceae |
Order: | Gonyaulacales |
Family: | Ostreopsidaceae |
Genus: | Coolia Meunier |
Coolia is a marine dinoflagellate genus in the family Ostreopsidaceae. It was first described by Meunier in 1919. [1] There are currently seven identified species distributed globally in tropical and temperate coastal waters. [2] 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. [3] It can also be found in a freely motile form in the water column. [3] [4] The life cycle of Coolia involves an asexual stage where the cell divides by binary fission and a sexual stage where cysts are produced. [5] Some of the species, for example, Coolia tropicalis and Coolia malayensis, produce toxins that can potentially cause shellfish poisoning in humans. [6]
The genus was named after a Pharmacist, M. Cool, from Nieupoort, Belgium, where the first species of the genus Coolia, Coolia monotis was originally discovered in the oyster beds. [1]
Coolia was first described by Alphonse Meunier (1919). [1] At the time of discovery, it was placed in its own monospecific genus. [7] At that time, the only species identified was Coolia monotis, which was discovered in oyster beds and the waters surrounding Nieupoort, Belgium. [1]
Between 1928 and 1956, Coolia monotis was placed in the same genus as Ostreopsis species, which is a genus also in the family Ostreopidaceae, because Coolia and Ostreopsis have similar patterns on their epithecae. [5] [7] In 1956 however, because of distinct differences in the hypotheca, it was put back into its individual genera in the family Ostreopidaceae. [7]
Coolia monotis remained the only species in the Coolia until 1995. In 1995, Coolia tropicalis was described. [8] In 2000, Coolia areolata was described. [4] In 2008, Coolia canariensis was described. [9] In 2010, Coolia malayensis was described. [10] Most recently in 2015, Coolia santacroce and Coolia palmyrensis were described. [11]
Species include:
Coolia has small spherical cells and is anteroposteriorly compressed. [1] [5] [4] [12] The cell size varies based on the species, but they have been typically reported to be approximately between 23-50 μm in length and 21-45 μm wide. [5] [8] [3] Coolia cells are distinguished by having a round hypotheca that is larger than their round epitheca. [5] [8] [7]
Coolia has plates covering the thecal surface that have an irregular pattern and are various sizes. [8] [4] [12] In most species, the thecal surface contains intercalary bands and is smooth and covered with large thecal pores that are round and ovoid. [5] [4] [10] Another distinguishing feature to identify Coolia is a plate on the epitheca that is off centred and contains an apical pore complex with a long, curved pore that has a slit containing two costae. [5] This apical pore is often visible because of its large size. [5] Coolia also has an ellipsoidal-shaped ventral pore on the ventral surface. [5]
From a dorsal view of the cell, the lipped cingulum (located equatorially) can be viewed. [5] The cingulum is narrow and the inside surface has round pores with smooth edges. There are also marginal pores surrounding the lipped cingulum. [5] Coolia also has a narrow sulcus that contains relatively short longitudinal flagellum at the posterior end. [5] As Coolia is photosynthetic, it contains golden-brown discoid chloroplasts. [5] The cells also only contain one nucleus with condensed chromosomes in the hypocone. [5]
Coolia has an asexual and a sexual life cycle. It is thought that under low nutrients, low light, or low temperature conditions, sexual reproduction may be initiated, resulting in the production of a resting cyst. [5] [12]
Cells divide asexually by binary fission. [5] The division process begins as the single nucleus with condensed chromosomes elongates and two nuclei develop parallel to each other. [5] Before dividing into daughter cells, the dividing cells stay attached to each other for approximately 12-24 hours. [5] The doubling time of Coolia is approximately 3-4 days [5]
Sexual reproduction occurs as gametes begin to form in the population; this is an irreversible transition. [5] Gametes move around each other rapidly and then align laterally, forming gamete pairs with the girdle and sulcus contacting each other, forming a fertilization bridge. [5] A planozygote is formed when the cells stop moving and the fertilization bridge disappears, allowing the two nuclei to join together. This indicates that karyogamy has occurred. [5] The theca then begins to develop and the cell becomes motile. [5] As the planozygote matures, it shrinks and becomes immobile, eventually developing into a cyst. [5] The cyst further develops to contain a single nucleus that makes up much of the volume of the cell. [5] At the end of the process, meiosis occurs. [5] The sexual life cycle is thought to last approximately 2 months. [5]
Phylogenetic analysis of different regions of rDNA supports the separate genus’ for Ostreopsis and Coolia. Analysis of 5.8S rDNA-ITS sequence alignments from European and Asian isolates and their out-groups supports distinct lineages of Ostreopsis and Coolia. [7] Lineages of Ostreopsis from Europe and Asia are genetically isolated and separate from lineages of Coolia from Europe and Asia. [7] This indicates that the lineages of Ostreopsis and Coolia evolved independently. [7] Additionally, analysis of LSU rDNA data shows that all the species of Coolia share a more recent common ancestor with each other than they do with Ostreopsis, who share a more recent common ancestor with other species in its genus. [3]
Coolia is found globally in coastal marine regions of both temperate and tropical waters. [2] Coolia monotis have a large habitat range and is found in tropical, sub-tropical, and temperate regions, whereas other species such as Coolia areolata and Coolia tropicalis have a more restricted range and are typically found in tropical regions. [7]
Coolia is typically a benthic type organism and can be attached to sandy substrates, coral, or brown and red seaweed. [4] [10] [3] In addition, it also can act as a planktonic organism and form blooms in the water column. [3]
Coolia, especially in tropical regions, forms assemblages with Gambierdiscus toxicus ; thus, they are often falsely described as being responsible for causing ciguatera. [11] [7] Ciguatera is actually caused by Gambierdiscus toxicus, not Coolia. [7] [11]
Coolia is considered a toxic dinoflagellate genus. Some of the species are known to be toxic and produce harmful algal blooms (HABs) that are of potential concern to human health. [6] They produce yessotoxins. [7] The species that are known to produce the toxins are Coolia tropicalis, Coolia malayensis, Coolia santacroce and Coolia palmyrensis. [6] [11] However, it is possible other species of the genus also produce toxins.
The dinoflagellates are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. 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.
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.
The genus Ceratium is restricted to a small number of freshwater dinoflagellate species. Previously the genus contained also a large number of marine dinoflagellate species. However, these marine species have now been assigned to a new genus called Tripos. Ceratium dinoflagellates are characterized by their armored plates, two flagella, and horns. They are found worldwide and are of concern due to their blooms.
Alexandrium tamarense is a species of dinoflagellates known to produce saxitoxin, a neurotoxin which causes the human illness clinically known as paralytic shellfish poisoning (PSP). Multiple species of phytoplankton are known to produce saxitoxin, including at least 10 other species from the genus Alexandrium.
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.
Ornithocercus is a genus of planktonic dinoflagellate that is known for its complex morphology that features considerable lists growing from its thecal plates, giving an attractive appearance. Discovered in 1883, this genus has a small number of species currently categorized but is widespread in tropical and sub-tropical oceans. The genus is marked by exosymbiotic bacteria gardens under its lists, the inter-organismal dynamics of which are a current field of research. As they reside only in warm water, the genus has been used as a proxy for climate change and has potential to be an indicator species for environmental change if found in novel environments.
Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters. It was first described in 1839 by Christian Gottfried Ehrenberg.
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.
Alexandrium catenella is a species of dinoflagellates. It is among the group of Alexandrium species that produce toxins that cause paralytic shellfish poisoning, and is a cause of red tide. ‘’Alexandrium catenella’’ is observed in cold, coastal waters, generally at temperate latitudes. These organisms have been found in the west coast of North America, Japan, Australia, and parts of South Africa.
Gambierdiscus belizeanus is a species of dinoflagellate, first found in Belize.
Coolia tropicalis is a species of dinoflagellates, first found in Belize.
Gambierdiscus pacificus is a species of toxic dinoflagellate. It is 67–77 μm long and 60–76 μm wide dorsoventrally and its surface is smooth. It is identified by a four-sided apical pore plate surrounded by 30 round pores. Its first plate occupies 20% of the width of the hypotheca.
The Polykrikaceae are a family of athecate dinoflagellates of the order Gymnodiniales. Members of the family are known as polykrikoids. The family contains two genera: Polykrikos and Pheopolykrikos.
Gambierdiscus is a genus of marine dinoflagellates that produce ciguatoxins, a type of toxin that causes the foodborne illness known as ciguatera. They are usually epiphytic on macroalgae growing on coral reefs.
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 dinoflagellates 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.
Blastodinium is a diverse genus of dinoflagellates and important parasites of planktonic copepods. They exist in either a parasitic stage, a trophont stage, and a dinospore stage. Although morphologically and functionally diverse, as parasites they live exclusively in the intestinal tract of copeods.
Ceratocorys is a genus of photosynthetic free-living marine dinoflagellates first described in 1883 by Friedrich Stein. Currently consisting of 12 species, this genus is typically found at the water surface in tropical and subtropical ocean regions, and has both low nutrient requirements and salinity sensitivity. All species in the genus have a theca; 29 membrane-bound armored plates with anywhere from 2 to 6 spines protruding from the cell. They reproduce through binary fission at temperatures above 20 °C during asexual reproduction and whether or not they have sexual reproduction is not known. Due to its bioluminescent capabilities, the type species of this genus, Ceratocorys horrida, has many practical applications. Its bioluminescent response to water flow means it can act as a model organism for understanding planktonic reaction to water movement. It is also sensitive to environmental molecules; by measuring the bioluminescent response it can be used in rapid toxicity tests to detect the levels of different contaminants in water systems. Its presence is also an indicator of different oceanic phenomena like upwellings or tropical waters.
Ostreopsis lenticularis is a species of dinoflagellate of the family Ostreopsidaceae described in 1981 by Yasuwo Fukuyo.