Ornithocercus

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Ornithocercus
Ornithocercus splendidus.jpg
Ornithocercus splendidus at 74 m in the Ionian sea
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Alveolata
Phylum: Myzozoa
Superclass: Dinoflagellata
Class: Dinophyceae
Order: Dinophysiales
Family: Dinophysaceae
Genus: Ornithocercus
Stein
Species [1]

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. [2] Discovered in 1883, this genus has a small number of species currently categorized but is widespread in tropical and sub-tropical oceans. [3] The genus is marked by exosymbiotic bacteria gardens under its lists, the inter-organismal dynamics of which are a current field of research. [4] 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. [5]

Contents

History of knowledge

Ornithocercus Magnificus: From the original species description Ornithocercus Magnificus drawing.jpg
Ornithocercus Magnificus: From the original species description

“…Ornithocercus, [so] strange, even the most sober researcher will have [to give] some admiration … Ornithocercusmagnificus, one of the most wonderful and strangest animal forms that ever happened to me” – Friedich Stein 1883 [6]

The genus Ornithocercus was first described in 1883 by German entomologist and zoologist Samuel Friedrich Nathaniel Ritter von Stein. He coined the genus with originally only one species: the holotype Ornithocercus magnificus. He made his observations in the Atlantic Ocean and named the organism with regards to the wonder its form inspired in him. [6]

Stein originally grouped Ornithocercus in the Dinophysiden, a German taxonomic term that is no longer utilized. He specifically paired it with the genus Histioneis due to their morphological distinctiveness including what he described as a head-funnel and neck collar. [6]

Ornithocercus magnificus from the Bay of Villefranche. The little orange balls are symbiotic cyanobacteria. Ornithocercus Magnificus image.jpg
Ornithocercus magnificus from the Bay of Villefranche. The little orange balls are symbiotic cyanobacteria.

Until DNA barcoding became accessible, specific demarcation in the genus was a significant challenge due to the variability in morphological traits (specifically the cingular lists). While beautiful figures were published in the early 20th century, often their scientific value was limited due to the incompleteness of morphological analyses. [7] Although the most fundamental taxonomic feature was the thecal structure, relatively few papers were available before the 1970s that critically analyzed thecal plates. Several works reported the number of plates incorrectly. [8] A review of previous publications and update with novel research published by Tohru Abe in 1967 indicated morphological features had been previously misinterpreted and given unwarranted significance taxonomically. [7]

Availability of enhanced microscope technology allowed greater morphological understanding. Scanning electron microscopes gave greater clarity to surface features as well as revealing the dissimilarity between inner and outer surfaces (such as pore openings) while transmission electron microscopes allowed insights into cell wall development. [9] The study of morphological variability within Ornithocercus species is an ongoing field. A 2018 study found that species O. quadratus could be three separate morphospecies based on inferences from modern imaging techniques of morphology. [10]

The genus is not as diverse as other dinoflagellate genera such as Dinophysis but does have at least 24 recognized species. [11] It has been extensively studied around the world, with species found to inhabit waters including the North Arabian Sea, Eastern Tropical Pacific, Indian Ocean, Red Sea, Vitiaz Strait, Caribbean Sea, Gulf of Aden, Southern Ocean, Boeton Str, California Current, Gulf of Mexico, Panamic Area, Peruvian Current Galapagos Eddy, and the coast of the Korean Peninsula. [2] [5] [8]

Habitat & ecology

Species of Ornithocercus are found in tropical and subtropical oceans, limited to warm temperature-waters. Tropical waters are home to many genera of dinophysoid, the most common of which is the Ornithocercus with O. quadratus being the most widely distributed species. [3] They are common in deep oceanic waters, with many species found predominantly below the euphotic zone. [9]

The existence of Ornithocercus in a brackish lagoon was also found in Terengganu at Gong Batu lagoon in Malaysia, indicating that it is not an isolated phenomenon. [12]

Morphology

Species range in length from 40-170 µm. [7] They are therefore classed as microplankton. [13]

Ornithocercus heteroporus - prominent lists on display Ornithocercus heteroporus (probably).jpg
Ornithocercus heteroporus - prominent lists on display

Ornithocercus is a thecate dinoflagellate. This means they are armored with overlapping cellulose plates collectively called a theca. The plates form within alveolae and therefore the wall is found within the cell membrane. [9] Lists are rigid outgrowths from edges of specific thecal plates supported by ribs. [14] The ribs vary in number and development between species (the number of ribs is species specific) and are necessary for expansive list growth. [9] The theca consists of 17 or 18 plates which are divided into epithecal, hypothecal, girdle, and ventral area. [9] The theca are divisible into left and right sides longitudinally by a sagittal suture; there is also a latitudinal girdle. [14] Structurally complex, the genus is characterized by possession of extensive girdle and sulcal lists (wing-like extensions of the cell wall). [2] Their theca have numerous pores which open flush to the surface of the plate on the outside but have a raised rim on the inside, their number being positively correlated with cell size. The hypotheca of most species are covered in areolae (shallow depressions) which are deepened by secondary thickening which takes place in mature cells. [9] While hypotheca of some Histioneis can be embedded in mucus, Ornithocercus species have not been observed with a hypotheca associated mucus layer. [15]

The elaborate morphology of the genus is thought to be a disadvantage during active swimming . [15] The lists have been posited to function in stability and creating feeding currents. The typical flagellar propulsion of dinoflagellates would be resisted by their morphology and the differences in list development between sides could act as a keel. The inhibition of rotation provided by their thecae would lead to increased water flow over parts of the cell which could enhance their feeding-current system. [9] One study found that the area in contact with the highest volume of external medium due to water flow is also a region where there are markedly less barriers to nutrient transfer (two less membranes - including theca). [15]

By comparing extant morphologies in dinoflagellate species, it has been suggested that ancestral species were benthic and had streamlined cells. As lifestyles became more planktonic, the large cingular and sulcal lists evolved alongside. [16]

Rhabdosomes, rod-shaped bodies found in the cytoplasm (approximately 3 µm in length and 0.25 µm), have been observed in Ornithocercus species. [4] They’re thought to function in prey capture as trichocysts although no signs of emission have ever been observed. The observation of a cytosome with a microtubular strand was used as evidence of potential food uptake via the peduncle. [4]

Feeding & symbiosis

Cyanobionts of Ornithocercus dinoflagellates Live cyanobionts (cyanobacterial symbionts) belonging to Ornithocercus dinoflagellate host consortium (a) O. magnificus with numerous cyanobionts present in the upper and lower girdle lists (black arrowheads) of the cingulum termed the symbiotic chamber. (b) O. steinii with numerous cyanobionts inhabiting the symbiotic chamber. (c) Enlargement of the area in (b) showing two cyanobionts that are being divided by binary transverse fission (white arrows). Cyanobacterial symbionts of Ornithocercus dinoflagellate 2.png
Cyanobionts of Ornithocercus dinoflagellates 
Live cyanobionts (cyanobacterial symbionts) belonging to Ornithocercus dinoflagellate host consortium
(a) O. magnificus with numerous cyanobionts present in the upper and lower girdle lists (black arrowheads) of the cingulum termed the symbiotic chamber.
(b) O. steinii with numerous cyanobionts inhabiting the symbiotic chamber.
(c) Enlargement of the area in (b) showing two cyanobionts that are being divided by binary transverse fission (white arrows).

Ornithocercus lacks photosynthetic pigments (and chloroplasts) and they are thus obligate heterotrophs. [18] Along with other heterotrophic dinoflagellate genera, they were thought to exclusively feed through osmotrophy of dissolved organic manner. [19]

While lacking the ability to photosynthesize, Ornithocercus has ectosymbiotic (extracellular) cyanobacteria. [16] The cyanobacterial symbionts known as phaeosomes are located between the upper and lower lists of the horizontal groove of the cells. [20] One study of these cyanobacteria symbiotes found that the cell size ranged from 3.5-10 µm (thus approximately an order of magnitude larger than prevalent planktonic Synechococcus forms). [21] A 2010 study found species to house both the described extracellular cyanobacteria as well as larger rod-shaped non-photosynthetic bacteria on their sulcal lists. [4]

The exact mechanism through which photosynthetic products of the bacteria are utilized by the host is still unclear. A 1994 study was conducted in the Gulf of Aqaba in which levels of colonial cyanobacteria were measured alongside oceanic nitrogen levels. Detection and peaking numbers of the consortia of heterotrophs (Ornithocercus) and autotrophs (cyanobacteria) at times of nitrogen limitation led the authors to propose that the hosts may be providing an anaerobic microenvironment in which the cyanobacteria can efficiently fix nitrogen. [19] This hypothetically could allow the consortia to thrive in stratified oligotrophic nitrogen limited waters. [19]   Recent studies called into question this conjecture as the cyanobacteria on two species of Ornithocercus were not found to produce the necessary enzyme nitrogenase. [22] The bacteria thus may provide fixed carbon for the host or may be used as a direct source of nutrients when they die. [20] Another study found that Ornithocercus has a nitrogenase gene (nifH) which supports the idea of additional nitrogen fixing heterotrophic symbionts, allowing the possibility that the bacterial garden hosted by Ornithocercus provides fixed carbon and nitrogen for the host. [23]

Food vacuoles have been observed inside O. magnificus with remnants of cyanobacterial symbionts enclosed. [4] In one study, some of the numerous food vacuoles observed inside Ornithocercus species strongly resembled the ectosymbionts in size and colour but were too degraded by section preparation to confirm via transmission electron microscopy. [4] The authors nonetheless concluded that it seemed likely the Ornithocercus were in effect growing their own “vegetables” and likely consuming the bacteria via a peduncle. They also found evidence that Ornithocercus may ingest ciliates, thus engaging in a multi-resource strategy to survive oligotrophic waters. [4]

An analysis of the genome of cyanobacteria associated with O. magnificus found that it had a reduced genome when compared to free-living cyanobacteria. [24] This indicates it had lost some genes as functions were provided for it by the host. However, its genome reduction was less severe than that seen in other cyanobacterial symbionts. Therefore it was proposed that the cyanobacteria is not dependent on the host for critical functions such as metabolism, thus supporting the theory that Ornithocercus feeds on its “garden” of bacteria. [24]

Life cycle

Ornithocercus grows by increasing the size of the individual cell wall elements slowly over time. [14] It also undergoes a period of rapid expansion laterally during cell division (binary fission). [14] The cell division growth is preceded by the formation of a band of material known as the megacytic zone which allows the mother cell wall to maintain integrity during cytokinesis as new cell wall pieces are duplicated. [14] This zone grows between the left and right sides of the theca. [9] The genus’ characteristic lists are reformed only after dissolution of the megacytic zone. [14] The last attachment between daughter cells is dorsally located and some species maintain attachment during early list development. [14]

It has been suggested that the hydrodynamic properties of lists are a reason that cells maintain contact after cell division. [14] As division leads to initially underdeveloped lists, by remaining together, the potential negative effects of lacking lists on stability and nutrition (assuming that is their normal function) could be reduced as they develop. [14]

Like other dinoflagellate genera, Ornithocercus has been found to show phased cell division (specific dividing times for species throughout the day). [25] By analyzing the states of the megacytic zones and bridges between daughter cells, a study off the coast of Brazil in the South Atlantic Ocean found that while cell division in O. steinii required high light intensity, O. magnificus and O. thumii utilized the days first light. [25]

Sexual reproduction and cyst formation are not known in Ornithocercus. [26]

Phylogeny

In the early 20th century, radiation schemes based on morphologies in cell structure were created for the order Dinophysiales (Dinophyceae) and were followed up with subsequent attempts utilizing more ecological and morphological data. [27] Recently, molecular phylogenetic studies have been undertaken which provide more accurate hypothetical frameworks for dinophysoid character evolution. A 2009 paper placed Ornithocercus in a group with Citharistes sharing a common ancestor but had insufficient data to label Ornithocercus as a monophyletic group (concluding however that it was a reasonable assumption that it is a monophyletic genus based on morphological similarities and sequence divergence estimates). [27] Another contemporary investigation including representative data for the genus Ornithocercus determined that it was in fact monophyletic. [28]

A 2013 study summarized the state of potential Ornithocercus phylogeny and placed them in clade with Citharistes and Histioneis with which the ectosymbiontic feature is shared. [16] This indicates that a common ancestor of these genera likely gained this relationship with cyanobacteria. Both Ornithocercus and Histioneis have cyanobacteria living between cingular lists whereas Citharistes have their ectosymbionts in a dorsal girdle-chamber. [16]

Practical importance

In 2008 a study was published in which temporal changes in dinoflagellate composition in coastal waters off the Korean Peninsula were analyzed. They found tropical oceanic species of Ornithocercus which were previously rare or unrecorded around the Peninsula. [29] A follow up study in 2013 confirmed the presence of numerous tropical dinoflagellate species including several species of Ornithocercus. [5] Together, the studies confirmed changes in phytoplankton communities in Korean waters by identifying dinoflagellate species changes, with the second paper both verifying the first and widening the scope of the changes. The authors suggest that these trends could be a result of increasing sea surface temperatures due to global warming. [5] [29] As such, Ornithocercus species could be used as indicator species and evidence for climate change and specifically marine ecosystem change if coupled with other environmental data. [5]

The Indian oil sardine (Sardinella longiceps) is one of the most important commercial fishes in India. [30]   These fish are known to occasionally feed heavily on Ornithocercus, specifically in the demersal zone (the study was performed off Mangalore). [31] As such, the welfare of Ornithocercus as a food chain link has commercial implications.

Related Research Articles

<span class="mw-page-title-main">Dinoflagellate</span> Unicellular algae with two flagella

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.

<i>Ceratium</i> Genus of single-celled organisms

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.

<i>Karenia</i> (dinoflagellate) Genus of single-celled organisms

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.

Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial or aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular structures of the host. In order for a cyanobacterium to successfully form a symbiotic relationship, it must be able to exchange signals with the host, overcome defense mounted by the host, be capable of hormogonia formation, chemotaxis, heterocyst formation, as well as possess adequate resilience to reside in host tissue which may present extreme conditions, such as low oxygen levels, and/or acidic mucilage. The most well-known plant-associated cyanobionts belong to the genus Nostoc. With the ability to differentiate into several cell types that have various functions, members of the genus Nostoc have the morphological plasticity, flexibility and adaptability to adjust to a wide range of environmental conditions, contributing to its high capacity to form symbiotic relationships with other organisms. Several cyanobionts involved with fungi and marine organisms also belong to the genera Richelia, Calothrix, Synechocystis, Aphanocapsa and Anabaena, as well as the species Oscillatoria spongeliae. Although there are many documented symbioses between cyanobacteria and marine organisms, little is known about the nature of many of these symbioses. The possibility of discovering more novel symbiotic relationships is apparent from preliminary microscopic observations.

<i>Peridinium</i> Genus of single-celled organisms

Peridinium is a genus of motile, marine and freshwater dinoflagellates. Their morphology is considered typical of the armoured dinoflagellates, and their form is commonly used in diagrams of a dinoflagellate's structure. Peridinium can range from 30 to 70 μm in diameter, and has very thick thecal plates.

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.

Histioneis is a genus of dinoflagellates. According to the World Register of Marine Species, it contains 86 species.

<i>Dinophysis</i> Genus of single-celled organisms

Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters. It was first described in 1839 by Christian Gottfried Ehrenberg.

<i>Akashiwo sanguinea</i> Species of single-celled organism

Akashiwo sanguinea is a species of marine dinoflagellates well known for forming blooms that result in red tides. The organism is unarmored (naked). Therefore, it lacks a thick cellulose wall, the theca, common in other genera of dinoflagellates. Reproduction of the phytoplankton species is primarily asexual.

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.

Karenia bicuneiformis, also known as Karenia bidigitata is a microbial species from the genus Karenia, which are dinoflagellates. It was first discovered in New Zealand.

<span class="mw-page-title-main">Warnowiaceae</span> Family of single-celled organisms

The Warnowiaceae are a family of athecate dinoflagellates. Members of the family are known as warnowiids. The family is best known for a light-sensitive subcellular structure known as the ocelloid, a highly complex arrangement of organelles with a structure directly analogous to the eyes of multicellular organisms. The ocelloid has been shown to be composed of multiple types of endosymbionts, namely mitochondria and at least one type of plastid.

<i>Erythropsidinium</i> Genus of single-celled organisms

Erythropsidinium is a genus of dinoflagellates of the family Warnowiaceae.

Trichodesmium thiebautii is a cyanobacteria that is often found in open oceans of tropical and subtropical regions and is known to be a contributor to large oceanic surface blooms. This microbial species is a diazotroph, meaning it fixes nitrogen gas (N2), but it does so without the use of heterocysts. T. thiebautii is able to simultaneously perform oxygenic photosynthesis. T. thiebautii was discovered in 1892 by M.A. Gomont. T. thiebautii are important for nutrient cycling in marine habitats because of their ability to fix N2, a limiting nutrient in ocean ecosystems.

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.

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.

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.

Torodinium (ˌtɔɹoʊˈdɪniəm) is a genus of unarmored dinoflagellates and comprises two species, Torodinium robustum and the type species Torodinium teredo. The establishment of Torodinium, as well as the characterization of the majority of its morphology, occurred in 1921 and further advances since have been slow. Lack of research is largely due to its extremely fragile and easily deformed nature, which also renders fossil records implausible. The genus was originally characterized by torsion of the sulcus and a posterior cingulum. Since then, new distinctive features have been discovered including an extremely reduced hyposome, a longitudinally ribbed episome, and a canal on the dextro-lateral side. Further investigation into the function of many anatomical features is still necessary for this genus.

Richelia is a genus of nitrogen-fixing, filamentous, heterocystous and cyanobacteria. It contains the single species Richelia intracellularis. They exist as both free-living organisms as well as symbionts within potentially up to 13 diatoms distributed throughout the global ocean. As a symbiont, Richelia can associate epiphytically and as endosymbionts within the periplasmic space between the cell membrane and cell wall of diatoms.

References

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  20. 1 2 Adams, David G. (2002), "Symbiotic Interactions", The Ecology of Cyanobacteria, Kluwer Academic Publishers, pp. 523–561, doi:10.1007/0-306-46855-7_19, ISBN   0792347358
  21. ↑ Carpenter, E. J.; Foster, R. A. (2003), "Marine Cyanobacterial Symbioses", Cyanobacteria in Symbiosis, Kluwer Academic Publishers, pp. 11–17, doi:10.1007/0-306-48005-0_2, ISBN   1402007779, S2CID   84134683
  22. ↑ Janson, Sven; Carpenter, Edward J.; Bergman, Birgitta (1995). "Immunolabelling of phycoerythrin, ribulose 1,5-bisphosphate carboxylase/oxygenase and nitrogenase in the unicellular cyanobionts of Ornithocercus spp. (Dinophyceae)". Phycologia. 34 (2): 171–176. doi:10.2216/i0031-8884-34-2-171.1. ISSN   0031-8884.
  23. ↑ Gagat, Przemysław; Bodył, Andrzej; Mackiewicz, Paweł; Stiller, John W. (2013-10-10), "Tertiary Plastid Endosymbioses in Dinoflagellates", Endosymbiosis, Springer Vienna, pp. 233–290, doi:10.1007/978-3-7091-1303-5_13, ISBN   9783709113028
  24. 1 2 Nakayama T, Takano Y, Nomura M, Shiba K, Inaba K, Tanifuji G, Inagaki Y, Kawata M (May 2018). Genome analysis of a symbiotic cyanobacterium in a dinophysialean dinoflagellate, Ornithocercus magnificus (PDF). XXII Meeting of the International Society of Evolutionary Protistology (Cyprus).
  25. 1 2 De AQUINO, Eveline Pinheiro de; HONORATO-DA-SILVA, Marcos; FEITOSA, Fernando Antônio do Nascimento; KOENING, Maria Luise; PASSAVANTE, José Zanon de Oliveira (2014-08-30). "Field observation of Ornithocercus spp. (Dinophysiales, Dinophyta): reproductive stages and phased cell division (South Atlantic Ocean, Brazil)". Tropical Oceanography. 42 (2). doi: 10.5914/tropocean.v42i2.5812 . ISSN   1679-3013.
  26. ↑ M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2019. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org  ; searched on 14 March 2019.
  27. 1 2 Jensen, Maria Hastrup; Daugbjerg, Niels (2009). "Molecular Phylogeny of Selected Species of the Order Dinophysiales (Dinophyceae)-Testing the Hypothesis of a Dinophysioid Radiation". Journal of Phycology. 45 (5): 1136–1152. doi:10.1111/j.1529-8817.2009.00741.x. PMID   27032359. S2CID   19359589.
  28. ↑ Handy, Sara M.; Bachvaroff, Tsvetan R.; Timme, Ruth E.; Wayne Coats, D.; Kim, Sunju; Delwiche, Charles F. (2009). "PHYLOGENY OF FOUR DINOPHYSIACEAN GENERA (DINOPHYCEAE, DINOPHYSIALES) BASED ON rDNA SEQUENCES FROM SINGLE CELLS AND ENVIRONMENTAL SAMPLES". Journal of Phycology. 45 (5): 1163–1174. doi:10.1111/j.1529-8817.2009.00738.x. PMID   27032361. S2CID   33929195.
  29. 1 2 Kim, Hyeung-Sin & Jung, Min-Min & Lee, Joon-Baek. (2008). The Korean Peninsula Warming Based on Appearance Trend of Tropical Dinoflagellate Species, Genus Ornithocercus. The Sea. Vol. 13. No. 4, pp 303-307.
  30. ↑ Balan, V (1963). "Studies on the age and growth of the Oil Sardine Sardinella longiceps by means of scales" (PDF). Indian Journal of Fisheries: 663–686.
  31. ↑ Dhulkhed, M H (1972) Food of the oil sardine taken by bottom nets And surface gill net in the mangalore area. Indian Journal of Fisheries, 19 (1&2). pp. 163-166.
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