| Pinnularia | |
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| Pinnularia major, specimen length 0.3 mm | |
Scientific classification  | |
| Domain: | Eukaryota |
| Clade: | Diaphoretickes |
| Clade: | SAR |
| Phylum: | Gyrista |
| Subphylum: | Ochrophytina |
| Class: | Bacillariophyceae |
| Order: | Naviculales |
| Family: | Pinnulariaceae |
| Genus: | Pinnularia Ehrenberg |
Pinnularia is a genus of fresh water algae, more specifically a type of diatom. [1]
Pinnularia is a predominantly fresh-water algae usually found in ponds and moist soil. [2] They can also be found in springs, estuaries, sediments, and oceans. Members of this genus are most commonly found in 40 cm (16 in) of water, at 5 °C (41 °F).
Pinnularia are elongated elliptical unicellular organisms. Their cell walls are composed chiefly of pectic substances on a rigid silica framework, and composed of two halves called thecae (or less formally, valves). These halves overlap like a Petri dish and its cover, the outer larger valve called Epitheca and the smaller called hypotheca. The margins of the two thecae are covered by a connecting band called a cingulum and all together are referred to as a frustule, and the whole cell is covered by a mucilaginous layer. The surface view is called valve view and band view is called girdle view. [3]
The cytoplasm is arranged approximately in layers conforming to the shape of the cell's walls. A large central vacuole is present with the nucleus suspended in its centre by a transverse cytoplasmic bridge. Two chloroplasts are present along the sides of the cells, and contain chlorophyll a, c, beta-carotene and fucoxanthin pigments. One or two pyrenoids are usually present in each chloroplast, although like many heterokont algae, Pinnularia tend to store their energy as fat. The cytoplasm also contains chrysolaminarin and some volutin.
Pinnularia, like most diatoms, can reproduce by simple cell division. Nuclear division occurs by mitosis and cell divides into two parts. Each daughter receives one of the parent cell's thecae, which becomes that cell's epitheca. The cell then synthesizes a new hypotheca. Thus, one daughter is the same size as the parent, and one is slightly smaller. With subsequent generations, the average cell size of a Pinnularia population gradually becomes smaller. When a minimum average size is reached, auxospore formation occurs and sexual reproduction restores the population's average cell size.
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites. The term comes from the Latin word cellula meaning 'small room'.
A chloroplast is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy-storage molecules ATP and NADPH while freeing oxygen from water in the cells. The ATP and NADPH is then used to make organic molecules from carbon dioxide in a process known as the Calvin cycle. Chloroplasts carry out a number of other functions, including fatty acid synthesis, amino acid synthesis, and the immune response in plants. The number of chloroplasts per cell varies from one, in unicellular algae, up to 100 in plants like Arabidopsis and wheat.
Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or centrioles, except in the gametes, and a unique method of cell division involving the formation of a cell plate or phragmoplast that separates the new daughter cells.
A diatom is any member of a large group comprising several genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of the Earth's biomass: they generate about 20 to 50 percent of the oxygen produced on the planet each year, take in over 6.7 billion tonnes of silicon each year from the waters in which they live, and constitute nearly half of the organic material found in the oceans. The shells of dead diatoms can reach as much as a half-mile deep on the ocean floor, and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by transatlantic winds from the African Sahara, much of it from the Bodélé Depression, which was once made up of a system of fresh-water lakes.
Charophyta is a group of freshwater green algae, called charophytes, sometimes treated as a division, yet also as a superdivision or an unranked clade. The terrestrial plants, the Embryophyta emerged within Charophyta, possibly from terrestrial unicellular charophytes, with the class Zygnematophyceae as a sister group.
Ulothrix is a genus of green algae in the family Ulotrichaceae.
Asterionella is a genus of pennate freshwater diatoms. They are frequently found in star-shaped colonies of individuals.
A resting spore is a resistant cell, used to survive adverse environmental conditions. Resting spore is a term commonly applied to both diatoms and fungi.
The Coscinodiscophyceae are a class(s) of diatoms. They are similar to the Centrales, a traditional, paraphyletic subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls of centric diatoms, which are circular or ellipsoid in valve view. The valves often bear radially symmetrical ornamental patterns that can appear as dots when viewed with an optical microscope. Some also bear spines on their valves, which may either increase cell surface area and reduce sinking, or act as a deterrent to zooplankton grazers. Unlike pennate diatoms, centric diatoms never have a raphe.
Chlorodendrales are an order of green, flagellated, thecate, unicellular eukaryotes, within the green algae class Chlorodendrophyceae. Prasinophyceae are defined by their cellular scales which are composed of carbohydrates, and Chlorodendrales are unique within this group due to these scales forming a fused thecal wall. Cells of Chlorodendrales are completely covered in scales, which fuse around the cell body producing the theca, but remain individually separated on the flagella, of which there are typically four per cell. Species within Chlorodendrales live in both marine and fresh water habitats, occupying both benthic and planktonic food webs. Additionally, they are photoautotrophs, meaning they produce their own food through the conversion of sunlight into chemical energy.
A frustule is the hard and porous cell wall or external layer of diatoms. The frustule is composed almost purely of silica, made from silicic acid, and is coated with a layer of organic substance, which was referred to in the early literature on diatoms as pectin, a fiber most commonly found in cell walls of plants. This layer is actually composed of several types of polysaccharides.
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.
Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters. It was first described in 1839 by Christian Gottfried Ehrenberg.
Chaetoceros pseudocurvisetus is a marine diatom in the genus Chaetoceros. It is an important primary producer in the oceans. C. pseudocurvisetus forms resting spores and resting cells, particularly in the absence of essential nutrients.
Dinophysis acuminata is a marine plankton species of dinoflagellates that is found in coastal waters of the north Atlantic and Pacific oceans. The genus Dinophysis includes both phototrophic and heterotrophic species. D. acuminata is one of several phototrophic species of Dinophysis classed as toxic, as they produce okadaic acid which can cause diarrhetic shellfish poisoning (DSP). Okadiac acid is taken up by shellfish and has been found in the soft tissue of mussels and the liver of flounder species. When contaminated animals are consumed, they cause severe diarrhoea. D. acuminata blooms are constant threat to and indication of diarrhoeatic shellfish poisoning outbreaks.
Dinophysis acuta is a species of flagellated planktons belonging to the genus Dinophysis. It is one of the few unusual photosynthetic protists that acquire plastids from algae by endosymbiosis. By forming massive blooms, particularly in late summer and spring, it causes red tides. It produces toxic substances and the red tides cause widespread infection of seafood, particularly crabs and mussels. When infected animals are consumed, severe diarrhoea occurs. The clinical symptom is called diarrhetic shellfish poisoning. The main chemical toxins were identified in 2006 as okadaic acid and pectenotoxins. They can produce non-fatal or fatal amounts of toxins in their predators, which can become toxic to humans.
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.
Cyclotella is a genus of diatoms often found in oligotrophic environments, both marine and fresh water. It is in the family Stephanodiscaceae and the order Thalassiosirales. The genus was first discovered in the mid 1800s and since then has become an umbrella genus for nearly 100 different species, the most well-studied and the best known being Cyclotella meneghiniana. Despite being among the most dominant genera in low-productivity environments, it is relatively understudied.
Leptocylindrus is a genus of diatoms belonging to the family Leptocylindraceae. They are long, cylindrical diatoms that are made up of multiple cells in a line. These cells have chloroplast to allow it to produce energy through photosynthesis by taking in sunlight and carbon dioxide to create sugars. the cells are attached at the cell walls called valves, the cell wall is slightly concave on one side and convex on the other so that the other cell wall attached will fit together.
| Authority control: National |
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