Temporal range: Ordovician to present
Dasycladales is an order of large unicellular green algae in the class Ulvophyceae.It contains two families, the Dasycladaceae and the Polyphysaceae.
In biological classification, the order is
The Ulvophyceae or ulvophytes are a class of green algae, distinguished mainly on the basis of ultrastructural morphology, life cycle and molecular phylogenetic data. The sea lettuce, Ulva, belongs here. Other well-known members include Caulerpa, Codium, Acetabularia, Cladophora, Trentepohlia and Monostroma.
The Dasycladaceae is one of the two extant families of green algae of the order Dasycladales. When found in Palaeozoic limestones, they typically indicate depositional depth of less than 5m.
These single celled algae are from 2 mm to 200 mm long. They live on substrates in shallow warm marine waters, usually less than 20 meters deep. They are very large cells. They are able to attain these sizes without numerous internal cell wells because they build calcium carbonate shells around themselves.
They contain only one nucleus in their vegetative stage, which remains in the bottom of the cell in the holdfast at the substrate. Only when they are ready to produce gametes does the nucleus undergo meiosis and then numerous mitoses into many nuclei which then migrate into the gametangia at the top of the alga.
In cell biology, the nucleus is a membrane-bound organelle found in eukaryotic cells. Eukaryotes usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate.
Meiosis is a special type of cell division that reduces the chromosome number by half, creating four haploid cells, each genetically distinct from the parent cell that gave rise to them. This process occurs in all sexually reproducing single-celled and multicellular eukaryotes, including animals, plants, and fungi. Errors in meiosis resulting in aneuploidy are the leading known cause of miscarriage and the most frequent genetic cause of developmental disabilities.
Because the nucleus is safely hidden in the holdfast, the cells easily regenerate if the top portions are broken off.
These algae are notable for having an intracellular network of 10 nm proteinaceous filaments, possibly for the storage and transport of ribonucleoprotein particles.
Because of all these properties, and the fact that they are easy to manipulate they have been favorite organisms in the study of the role of the nucleus vs the unnucleated cytoplasm in the behavior of cells.
In cell biology, the cytoplasm is all of the material within a cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. The main components of the cytoplasm are cytosol – a gel-like substance, the organelles – the cell's internal sub-structures, and various cytoplasmic inclusions. The cytoplasm is about 80% water and usually colorless.
The cell is the basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life. Cells are often called the "building blocks of life". The study of cells is called cell biology or cellular biology.
The brown algae, comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Most brown algae live in marine environments, where they play an important role both as food and as habitat. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests. Kelp forests like these contain a high level of biodiversity. Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Some members of the class, such as kelps, are used by humans as food.
A coenocyte is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes inside the mass. The word syncytium in animal embryology is used to refer to the coenocytic blastoderm of invertebrates.
Acetabularia is a genus of green algae in the family Polyphysaceae, Typically found in subtropical waters, Acetabularia is a single-celled organism, but gigantic in size and complex in form, making it an excellent model organism for studying cell biology. In form, the mature Acetabularia resembles the round leaves of a nasturtium, is 0.5 to 10 cm tall and has three anatomical parts: a bottom rhizoid that resembles a set of short roots; a long stalk in the middle; and a top umbrella of branches that may fuse into a cap. The single nucleus of Acetabularia is located in the rhizoid, and allows the cell to regenerate completely if its cap is removed. The caps of two Acetabularia may also be exchanged, even from two different species. In addition, if a piece of the stem is removed, with no access to the nucleus in the rhizoid, this isolated stem piece will also grow a new cap.
Palmaria palmata, also called dulse, dillisk or dilsk, red dulse, sea lettuce flakes, or creathnach, is a red alga (Rhodophyta) previously referred to as Rhodymenia palmata. It grows on the northern coasts of the Atlantic and Pacific Oceans. It is a well-known snack food. In Iceland, where it is known as söl, it has been an important source of dietary fiber throughout the centuries.
Laminaria is a genus of 31 species of brown algae commonly called "kelp". Some species are also referred to as tangle. This economically important genus is characterized by long, leathery laminae and relatively large size. Some species are referred to by the common name Devil's apron, due to their shape, or sea colander, due to the perforations present on the lamina. It is found in the north Atlantic Ocean and the northern Pacific Ocean at depths from 8 to 30 m. Laminaria form a habitat for many fish and invertebrates.
Nostoc is a genus of cyanobacteria found in various environments that forms colonies composed of filaments of moniliform cells in a gelatinous sheath.
Oedogonium is a genus of filamentous green algae, with unbranched filaments that are one cell thick. Oedogonium can be free-floating, though it is usually attached to aquatic plants by a holdfast. It appears greenish and inhabits calm, fresh water.
The Fucales (fucoids) are an order in the brown algae. The list of families in the Fucales, as well as additional taxonomic information on algae, is publicly accessible at Algaebase.
Mastocarpus stellatus, also called Clúimhín Cait, carragheen, or false Irish moss, is a species of red algae closely related to Irish Moss, or Chondrus crispus. It is collected in Ireland and Scotland, together with Chondrus crispus as Irish moss, dried, and sold for cooking and as the basis for a drink reputed to ward off colds and flu.
Ectocarpales is a very large order in the brown algae. The order includes families with pseudoparenchymatous (Splachnidiaceae) or true parenchymatous (Scytosiphonaceae) tissue. Pseudoparenchymatous refers to a filamentous alga with cells packed very close together to give an appearance of parenchymatous tissue, the latter being composed of cells which can truly divide in three dimensions, unusual among the algae. Filamentous algae are composed of cells that divide along a single plane, allowing only elongation to form filaments of one or more rows of cells. Algae that can divide in two planes can form sheet-like thalli or bodies. Cells that can divide in a third plane potentially allow for the organism to develop a more complex body plan, and diversification of body plans into an erect thallus of some sort and a holdfast for attaching the upright portion to the substrate.
Bryopsidales is an order of green algae, in the class Ulvophyceae.
In algal anatomy, a pit connection is a hole in the septum between two algal cells, and is found only in the red algae − specifically, all orders except the Porphyridiales and haploid Bangiales. They are often stoppered with proteinaceous "pit plugs". By contrast, many fungi contain septal pores − an unrelated phenomenon.
Desmarestia viridis is a species of brown algae found worldwide. Its common names include stringy acid kelp, green acid kelp, Desmarest's green weed, and sea sorrel, though the last name can refer to other species of Desmarestia. The light brown thallus is delicate with a disc-shaped holdfast. It releases sulfuric acid when damaged, destroying itself and nearby seaweeds in the process. They are found in shallow intertidal areas.
Nostoc commune is a species of cyanobacterium in the family Nostocaceae. Common names include star jelly, witch's butter, mare's eggs, fah-tsai and facai. It is the type species of the genus Nostoc and is cosmopolitan in distribution.
Acetabularia caliculus, the umbrella alga, is a species of green alga found in shallow temperate and tropical seas.
Chaetomorpha linum is a species of green algae in the family Cladophoraceae.
Cell mechanics is a sub-field of biophysics that focuses on the mechanical properties and behavior of living cells and how it relates to cell function. It encompasses aspects of cell biophysics, biomechanics, soft matter physics and rheology, mechanobiology and cell biology.
Polysiphonia elongella Harvey in W.J. Hooker is a branched species of marine red algae in the genus in the Polysiphonia in the Rhodophyta.
Porphyra purpurea is a medium sized marine algae in the Division Rhodophyta.
The International Standard Book Number (ISBN) is a numeric commercial book identifier which is intended to be unique. Publishers purchase ISBNs from an affiliate of the International ISBN Agency.
Carnets de Géologie is an electronic journal that publishes in the field of geosciences, and particularly paleontology, stratigraphy, and sedimentology. The open-access journal is one of the founding members of the OA portal Geoscience e-Journals. Since 2007, it is published by the eponymic association Carnets de Géologie at the University of Western Brittany in Brest, France.
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