Misplaced Pages

#844155

43-760: In November 2006, the lake's entire trout population died, possibly due to algae . The name Totensee (also: Lake Toten , literally "Lake of the Dead") is said to be derived from soldiers of Duke Berchtold V of Zähringen driven into the lake by the people of Valais after the Battle of Ulrichen in 1211. This article related to a lake in Valais is a stub . You can help Misplaced Pages by expanding it . Algae Algae ( UK : / ˈ æ l ɡ iː / AL -ghee , US : / ˈ æ l dʒ iː / AL -jee ; sg. : alga / ˈ æ l ɡ ə / AL -gə )

86-571: A and b . Their chloroplasts are surrounded by four and three membranes, respectively, and were probably retained from ingested green algae. Chlorarachniophytes , which belong to the phylum Cercozoa , contain a small nucleomorph , which is a relict of the algae's nucleus . Euglenids , which belong to the phylum Euglenozoa , live primarily in fresh water and have chloroplasts with only three membranes. The endosymbiotic green algae may have been acquired through myzocytosis rather than phagocytosis . (Another group with green algae endosymbionts

129-408: A and c , and phycobilins. The shape can vary; they may be of discoid, plate-like, reticulate, cup-shaped, spiral, or ribbon shaped. They have one or more pyrenoids to preserve protein and starch. The latter chlorophyll type is not known from any prokaryotes or primary chloroplasts, but genetic similarities with red algae suggest a relationship there. In the first three of these groups ( Chromista ),

172-528: A polyphyletic group since they do not include a common ancestor , and although their chlorophyll -bearing plastids seem to have a single origin (from symbiogenesis with cyanobacteria ), they were acquired in different ways. Green algae are a prominent examples of algae that have primary chloroplasts derived from endosymbiont cyanobacteria. Diatoms and brown algae are examples of algae with secondary chloroplasts derived from endosymbiotic red algae , which they acquired via phagocytosis . Algae exhibit

215-539: A form and capabilities not possessed by the symbiont species alone (they can be experimentally isolated). The photobiont possibly triggers otherwise latent genes in the mycobiont. Trentepohlia is an example of a common green alga genus worldwide that can grow on its own or be lichenised. Lichen thus share some of the habitat and often similar appearance with specialized species of algae ( aerophytes ) growing on exposed surfaces such as tree trunks and rocks and sometimes discoloring them. Coral reefs are accumulated from

258-426: A higher number of clades as research demonstrates that organic forms of nitrogen and phosphorus—such as DNA, proteins, amino-acids or carbohydrates—are also part of the nutrient supplies of a number of plant species. Mixotrophy is less common among animals than among plants and microbes, but there are many examples of mixotrophic invertebrates and at least one example of a mixotrophic vertebrate . To characterize

301-598: A lineage that eventually led to the higher land plants. The innovation that defines these nonalgal plants is the presence of female reproductive organs with protective cell layers that protect the zygote and developing embryo. Hence, the land plants are referred to as the Embryophytes . The term algal turf is commonly used but poorly defined. Algal turfs are thick, carpet-like beds of seaweed that retain sediment and compete with foundation species like corals and kelps , and they are usually less than 15 cm tall. Such

344-483: A red dye derived from it. The Latinization, fūcus , meant primarily the cosmetic rouge. The etymology is uncertain, but a strong candidate has long been some word related to the Biblical פוך ( pūk ), 'paint' (if not that word itself), a cosmetic eye-shadow used by the ancient Egyptians and other inhabitants of the eastern Mediterranean. It could be any color: black, red, green, or blue. The study of algae

387-538: A trophic mode is obligate, then it is always necessary for sustaining growth and maintenance; if facultative, it can be used as a supplemental source. Some organisms have incomplete Calvin cycles , so they are incapable of fixing carbon dioxide and must use organic carbon sources. Organisms may employ mixotrophy obligately or facultatively . Amongst plants, mixotrophy classically applies to carnivorous , hemi-parasitic and myco-heterotrophic species. However, this characterisation as mixotrophic could be extended to

430-468: A turf may consist of one or more species, and will generally cover an area in the order of a square metre or more. Some common characteristics are listed: Many algae, particularly species of the Characeae , have served as model experimental organisms to understand the mechanisms of the water permeability of membranes, osmoregulation , turgor regulation , salt tolerance , cytoplasmic streaming , and

473-989: A wide range of reproductive strategies, from simple asexual cell division to complex forms of sexual reproduction via spores . Algae lack the various structures that characterize plants (which evolved from freshwater green algae), such as the phyllids (leaf-like structures) and rhizoids of bryophytes ( non-vascular plants ), and the roots , leaves and other xylemic / phloemic organs found in tracheophytes ( vascular plants ). Most algae are autotrophic , although some are mixotrophic , deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy , myzotrophy or phagotrophy . Some unicellular species of green algae, many golden algae , euglenids , dinoflagellates , and other algae have become heterotrophs (also called colorless or apochlorotic algae), sometimes parasitic , relying entirely on external energy sources and have limited or no photosynthetic apparatus. Some other heterotrophic organisms, such as

SECTION 10

#1732776745845

516-454: Is an informal term for any organisms of a large and diverse group of photosynthetic eukaryotes , which include species from multiple distinct clades . Such organisms range from unicellular microalgae such as Chlorella , Prototheca and the diatoms , to multicellular macroalgae such as the giant kelp , a large brown alga which may grow up to 50 metres (160 ft) in length. Most algae are aquatic organisms and lack many of

559-550: Is most commonly called phycology (from Greek phykos  'seaweed'); the term algology is falling out of use. One definition of algae is that they "have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells ". On the other hand, the colorless Prototheca under Chlorophyta are all devoid of any chlorophyll. Although cyanobacteria are often referred to as "blue-green algae", most authorities exclude all prokaryotes , including cyanobacteria, from

602-544: Is quite different from those of reds and browns, because they have distinct nodes, separated by internode 'stems'; whorls of branches reminiscent of the horsetails occur at the nodes. Conceptacles are another polyphyletic trait; they appear in the coralline algae and the Hildenbrandiales , as well as the browns. Most of the simpler algae are unicellular flagellates or amoeboids , but colonial and nonmotile forms have developed independently among several of

645-528: Is the Latin word for 'seaweed' and retains that meaning in English. The etymology is obscure. Although some speculate that it is related to Latin algēre , 'be cold', no reason is known to associate seaweed with temperature. A more likely source is alliga , 'binding, entwining'. The Ancient Greek word for 'seaweed' was φῦκος ( phŷkos ), which could mean either the seaweed (probably red algae) or

688-423: Is the dinoflagellate genus Lepidodinium , which has replaced its original endosymbiont of red algal origin with one of green algal origin. A nucleomorph is present, and the host genome still have several red algal genes acquired through endosymbiotic gene transfer. Also the euglenid and chlorarachniophyte genome contain genes of apparent red algal ancestry) These groups have chloroplasts containing chlorophylls

731-601: Is thus protected from predators; the sponge is provided with oxygen and sugars which can account for 50 to 80% of sponge growth in some species. Mixotroph A mixotroph is an organism that uses a mix of different sources of energy and carbon , instead of having a single trophic mode, on the continuum from complete autotrophy to complete heterotrophy . It is estimated that mixotrophs comprise more than half of all microscopic plankton . There are two types of eukaryotic mixotrophs. There are those with their own chloroplasts - including those with endosymbionts providing

774-751: The Calymmian period , early in Boring Billion , but it is difficult to track the key events because of so much time gap. Primary symbiogenesis gave rise to three divisions of archaeplastids , namely the Viridiplantae ( green algae and later plants ), Rhodophyta ( red algae ) and Glaucophyta ("grey algae"), whose plastids further spread into other protist lineages through eukaryote-eukaryote predation , engulfments and subsequent endosymbioses (secondary and tertiary symbiogenesis). This process of serial cell "capture" and "enslavement" explains

817-614: The Infusoria (microscopic organisms). Unlike macroalgae , which were clearly viewed as plants, microalgae were frequently considered animals because they are often motile. Even the nonmotile (coccoid) microalgae were sometimes merely seen as stages of the lifecycle of plants, macroalgae, or animals. Although used as a taxonomic category in some pre-Darwinian classifications, e.g., Linnaeus (1753), de Jussieu (1789), Lamouroux (1813), Harvey (1836), Horaninow (1843), Agassiz (1859), Wilson & Cassin (1864), in further classifications,

860-612: The International Association for Lichenology to be "an association of a fungus and a photosynthetic symbiont resulting in a stable vegetative body having a specific structure". The fungi, or mycobionts, are mainly from the Ascomycota with a few from the Basidiomycota . In nature, they do not occur separate from lichens. It is unknown when they began to associate. One or more mycobiont associates with

903-589: The Late Cambrian / Early Ordovician period, from sessile shallow freshwater charophyte algae much like Chara , which likely got stranded ashore when riverine / lacustrine water levels dropped during dry seasons . These charophyte algae probably already developed filamentous thalli and holdfasts that superficially resembled plant stems and roots , and probably had an isomorphic alternation of generations . They perhaps evolved some 850 mya and might even be as early as 1  Gya during

SECTION 20

#1732776745845

946-986: The Vindhya basin have been dated to 1.6 to 1.7 billion years ago. Because of the wide range of algae types, they have increasingly different industrial and traditional applications in human society. Traditional seaweed farming practices have existed for thousands of years and have strong traditions in East Asia food cultures. More modern algaculture applications extend the food traditions for other applications, including cattle feed, using algae for bioremediation or pollution control, transforming sunlight into algae fuels or other chemicals used in industrial processes, and in medical and scientific applications. A 2020 review found that these applications of algae could play an important role in carbon sequestration to mitigate climate change while providing lucrative value-added products for global economies. The singular alga

989-601: The apicomplexans are also parasites derived from ancestors that possessed plastids, but are not included in any group traditionally seen as algae. Algae are polyphyletic thus their origin cannot be traced back to single hypothetical common ancestor . It is thought that they came into existence when photosynthetic coccoid cyanobacteria got phagocytized by a unicellular heterotrophic eukaryote (a protist ), giving rise to double-membranous primary plastids . Such symbiogenic events (primary symbiogenesis) are believed to have occurred more than 1.5 billion years ago during

1032-435: The apicomplexans , are also derived from cells whose ancestors possessed chlorophyllic plastids, but are not traditionally considered as algae. Algae have photosynthetic machinery ultimately derived from cyanobacteria that produce oxygen as a byproduct of splitting water molecules , unlike other organisms that conduct anoxygenic photosynthesis such as purple and green sulfur bacteria . Fossilized filamentous algae from

1075-545: The calcareous exoskeletons of marine invertebrates of the order Scleractinia (stony corals ). These animals metabolize sugar and oxygen to obtain energy for their cell-building processes, including secretion of the exoskeleton, with water and carbon dioxide as byproducts. Dinoflagellates (algal protists) are often endosymbionts in the cells of the coral-forming marine invertebrates, where they accelerate host-cell metabolism by generating sugar and oxygen immediately available through photosynthesis using incident light and

1118-720: The "algae" are seen as an artificial, polyphyletic group. Throughout the 20th century, most classifications treated the following groups as divisions or classes of algae: cyanophytes , rhodophytes , chrysophytes , xanthophytes , bacillariophytes , phaeophytes , pyrrhophytes ( cryptophytes and dinophytes ), euglenophytes , and chlorophytes . Later, many new groups were discovered (e.g., Bolidophyceae ), and others were splintered from older groups: charophytes and glaucophytes (from chlorophytes), many heterokontophytes (e.g., synurophytes from chrysophytes, or eustigmatophytes from xanthophytes), haptophytes (from chrysophytes), and chlorarachniophytes (from xanthophytes). With

1161-675: The abandonment of plant-animal dichotomous classification, most groups of algae (sometimes all) were included in Protista , later also abandoned in favour of Eukaryota . However, as a legacy of the older plant life scheme, some groups that were also treated as protozoans in the past still have duplicated classifications (see ambiregnal protists ). Some parasitic algae (e.g., the green algae Prototheca and Helicosporidium , parasites of metazoans, or Cephaleuros , parasites of plants) were originally classified as fungi , sporozoans , or protistans of incertae sedis , while others (e.g.,

1204-451: The carbon dioxide produced by the host. Reef-building stony corals ( hermatypic corals ) require endosymbiotic algae from the genus Symbiodinium to be in a healthy condition. The loss of Symbiodinium from the host is known as coral bleaching , a condition which leads to the deterioration of a reef. Endosymbiontic green algae live close to the surface of some sponges, for example, breadcrumb sponges ( Halichondria panicea ). The alga

1247-420: The chloroplast has four membranes, retaining a nucleomorph in cryptomonads , and they likely share a common pigmented ancestor, although other evidence casts doubt on whether the heterokonts , Haptophyta , and cryptomonads are in fact more closely related to each other than to other groups. The typical dinoflagellate chloroplast has three membranes, but considerable diversity exists in chloroplasts within

1290-492: The chloroplasts. And there are those that acquire them through kleptoplasty , or through symbiotic associations with prey, or through 'enslavement' of the prey's organelles. Possible combinations are photo- and chemotrophy , litho- and organotrophy ( osmotrophy , phagotrophy and myzocytosis ), auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic . They can take advantage of different environmental conditions. If

1333-624: The composition of the three major groups of algae. Their lineage relationships are shown in the figure in the upper right. Many of these groups contain some members that are no longer photosynthetic. Some retain plastids, but not chloroplasts, while others have lost plastids entirely. Phylogeny based on plastid not nucleocytoplasmic genealogy: Cyanobacteria Glaucophytes Rhodophytes Stramenopiles Cryptophytes Haptophytes Euglenophytes Chlorarachniophytes Chlorophytes Charophytes Land plants (Embryophyta) These groups have green chloroplasts containing chlorophylls

Totesee - Misplaced Pages Continue

1376-436: The definition of algae. The algae contain chloroplasts that are similar in structure to cyanobacteria. Chloroplasts contain circular DNA like that in cyanobacteria and are interpreted as representing reduced endosymbiotic cyanobacteria . However, the exact origin of the chloroplasts is different among separate lineages of algae, reflecting their acquisition during different endosymbiotic events. The table below describes

1419-499: The distinct cell and tissue types, such as stomata , xylem and phloem that are found in land plants . The largest and most complex marine algae are called seaweeds . In contrast, the most complex freshwater forms are the Charophyta , a division of green algae which includes, for example, Spirogyra and stoneworts . Algae that are carried passively by water are plankton , specifically phytoplankton . Algae constitute

1462-425: The diversity of photosynthetic eukaryotes. Recent genomic and phylogenomic approaches have significantly clarified plastid genome evolution , the horizontal movement of endosymbiont genes to the "host" nuclear genome , and plastid spread throughout the eukaryotic tree of life . Fossils of isolated spores suggest land plants may have been around as long as 475  million years ago (mya) during

1505-432: The first to divide macroscopic algae into four divisions based on their pigmentation. This is the first use of a biochemical criterion in plant systematics. Harvey's four divisions are: red algae (Rhodospermae), brown algae (Melanospermae), green algae (Chlorospermae), and Diatomaceae. At this time, microscopic algae were discovered and reported by a different group of workers (e.g., O. F. Müller and Ehrenberg ) studying

1548-538: The genera Volvox and Corallina , and a species of Acetabularia (as Madrepora ), among the animals. In 1768, Samuel Gottlieb Gmelin (1744–1774) published the Historia Fucorum , the first work dedicated to marine algae and the first book on marine biology to use the then new binomial nomenclature of Linnaeus. It included elaborate illustrations of seaweed and marine algae on folded leaves. W. H. Harvey (1811–1866) and Lamouroux (1813) were

1591-446: The generation of action potentials . Plant hormones are found not only in higher plants, but in algae, too. Some species of algae form symbiotic relationships with other organisms. In these symbioses, the algae supply photosynthates (organic substances) to the host organism providing protection to the algal cells. The host organism derives some or all of its energy requirements from the algae. Examples are: Lichens are defined by

1634-538: The green algae Phyllosiphon and Rhodochytrium , parasites of plants, or the red algae Pterocladiophila and Gelidiocolax mammillatus , parasites of other red algae, or the dinoflagellates Oodinium , parasites of fish) had their relationship with algae conjectured early. In other cases, some groups were originally characterized as parasitic algae (e.g., Chlorochytrium ), but later were seen as endophytic algae. Some filamentous bacteria (e.g., Beggiatoa ) were originally seen as algae. Furthermore, groups like

1677-571: The group, and a number of endosymbiotic events apparently occurred. The Apicomplexa , a group of closely related parasites, also have plastids called apicoplasts , which are not photosynthetic, but appear to have a common origin with dinoflagellate chloroplasts. Linnaeus , in Species Plantarum (1753), the starting point for modern botanical nomenclature , recognized 14 genera of algae, of which only four are currently considered among algae. In Systema Naturae , Linnaeus described

1720-453: The groups. Some of the more common organizational levels, more than one of which may occur in the lifecycle of a species, are In three lines, even higher levels of organization have been reached, with full tissue differentiation. These are the brown algae, —some of which may reach 50 m in length ( kelps ) —the red algae, and the green algae. The most complex forms are found among the charophyte algae (see Charales and Charophyta ), in

1763-417: The late phase of the Boring Billion . A range of algal morphologies is exhibited, and convergence of features in unrelated groups is common. The only groups to exhibit three-dimensional multicellular thalli are the reds and browns , and some chlorophytes . Apical growth is constrained to subsets of these groups: the florideophyte reds, various browns, and the charophytes. The form of charophytes

Totesee - Misplaced Pages Continue

1806-405: The same phycobiont species, from the green algae, except that alternatively, the mycobiont may associate with a species of cyanobacteria (hence "photobiont" is the more accurate term). A photobiont may be associated with many different mycobionts or may live independently; accordingly, lichens are named and classified as fungal species. The association is termed a morphogenesis because the lichen has

1849-458: The sub-domains within mixotrophy, several very similar categorization schemes have been suggested. Consider the example of a marine protist with heterotrophic and photosynthetic capabilities: In the breakdown put forward by Jones, there are four mixotrophic groups based on relative roles of phagotrophy and phototrophy. An alternative scheme by Stoeker also takes into account the role of nutrients and growth factors, and includes mixotrophs that have

#844155