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41-400: Myxozoa ( etymology : Greek : μύξα myxa "slime" or "mucus" + thematic vowel o + ζῷον zoon "animal") is a subphylum of aquatic cnidarian animals – all obligate parasites . It contains the smallest animals ever known to have lived. Over 2,180 species have been described and some estimates have suggested at least 30,000 undiscovered species. Many have a two-host lifecycle, involving

82-586: A fish and an annelid worm or a bryozoan . The average size of a myxosporean spore usually ranges from 10 μm to 20 μm, whereas that of a malacosporean (a subclade of the Myxozoa) spore can be up to 2 mm. Myxozoans can live in both freshwater and marine habitats. Myxozoans are highly derived cnidarians that have undergone dramatic evolution from a free swimming, self-sufficient jellyfish -like creature into their current form of obligate parasites composed of very few cells – sometimes only

123-410: A common parent language. Doublets or etymological twins or twinlings (or possibly triplets, and so forth) are specifically cognates within the same language. Although they have the same etymological root, they tend to have different phonological forms, and to have entered the language through different routes. A root is the source of related words within a single language (no language barrier

164-955: A high standard with the German Dictionary of the Brothers Grimm . The successes of the comparative approach culminated in the Neogrammarian school of the late 19th century. Still in the 19th century, German philosopher Friedrich Nietzsche used etymological strategies (principally and most famously in On the Genealogy of Morals , but also elsewhere) to argue that moral values have definite historical (specifically, cultural) origins where modulations in meaning regarding certain concepts (such as "good" and "evil") show how these ideas had changed over time—according to which value-system appropriated them. This strategy gained popularity in

205-508: A limited number of basic mechanisms, the most important of which are language change , borrowing (i.e., the adoption of " loanwords " from other languages); word formation such as derivation and compounding ; and onomatopoeia and sound symbolism (i.e., the creation of imitative words such as "click" or "grunt"). While the origin of newly emerged words is often more or less transparent, it tends to become obscured through time due to sound change or semantic change. Due to sound change , it

246-463: A long written history , etymologists make use of texts, particularly texts about the language itself, to gather knowledge about how words were used during earlier periods, how they developed in meaning and form , or when and how they entered the language. Etymologists also apply the methods of comparative linguistics to reconstruct information about forms that are too old for any direct information to be available. By analyzing related languages with

287-399: A single cell . As myxozoans evolved into microscopic parasites, they lost many genes responsible for multicellular development, coordination, cell–cell communication , and even, in some cases, aerobic respiration . The genomes of some myxozoans are now among the smallest genomes of any known animal species. Myxozoans are endoparasitic animals exhibiting complex life cycles that, in most of

328-520: A technique known as the comparative method , linguists can make inferences about their shared parent language and its vocabulary. In this way, word roots in many European languages, for example, can be traced back to the origin of the Indo-European language family . Even though etymological research originated from the philological tradition, much current etymological research is done on language families where little or no early documentation

369-405: A worm-like parasite of bryozoans up to 2 mm in length, is a myxozoan initially appeared to strengthen the case for a bilaterian origin, as the body plan is superficially similar. Nevertheless, closer examination reveals that Buddenbrockia 's longitudinal symmetry is not twofold, but fourfold, casting doubt on this hypothesis . Further testing resolved the genetic conundrum by sourcing

410-484: Is available, such as Uralic and Austronesian . The word etymology is derived from the Ancient Greek word ἐτυμολογία ( ἐτυμολογία ), itself from ἔτυμον ( ἔτυμον ), meaning ' true sense or sense of a truth ' , and the suffix -logia , denoting ' the study or logic of ' . The etymon refers to the predicate (i.e. stem or root ) from which a later word or morpheme derives. For example,

451-399: Is crossed). Similar to the distinction between etymon and root , a nuanced distinction can sometimes be made between a descendant and a derivative . A derivative is one of the words which have their source in a root word, and were at some time created from the root word using morphological constructs such as suffixes, prefixes, and slight changes to the vowels or to the consonants of

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492-616: Is known. The earliest of attested etymologies can be found in Vedic literature in the philosophical explanations of the Brahmanas , Aranyakas , and Upanishads . The analyses of Sanskrit grammar done by the previously mentioned linguists involved extensive studies on the etymology (called Nirukta or Vyutpatti in Sanskrit) of Sanskrit words, because the ancient Indians considered sound and speech itself to be sacred and, for them,

533-478: Is not readily obvious that the English word set is related to the word sit (the former is originally a causative formation of the latter). It is even less obvious that bless is related to blood (the former was originally a derivative with the meaning "to mark with blood"). Semantic change may also occur. For example, the English word bead originally meant "prayer". It acquired its modern meaning through

574-528: Is often traced to Sir William Jones , a Welsh philologist living in India , who in 1782 observed the genetic relationship between Sanskrit , Greek and Latin . Jones published his The Sanscrit Language in 1786, laying the foundation for the field of Indo-European linguistics . The study of etymology in Germanic philology was introduced by Rasmus Christian Rask in the early 19th century and elevated to

615-552: Is the most absurd, which derives this word from pons, and assigns the priests the title of bridge-makers. The sacrifices performed on the bridge were amongst the most sacred and ancient, and the keeping and repairing of the bridge attached, like any other public sacred office, to the priesthood. Isidore of Seville compiled a volume of etymologies to illuminate the triumph of religion. Each saint's legend in Jacobus de Varagine 's Legenda Aurea begins with an etymological discourse on

656-533: Is the reflex of the Old English hǣtu. Rarely, this word is used in reverse, and the 'reflex' is actually the root word rather than the descendant word. However, this usage is usually filled by the term etymon instead. A reflex will sometimes be described simply as a descendant , derivative or derived from an etymon (but see below). Cognates or lexical cognates are sets of words that have been inherited in direct descent from an etymological ancestor in

697-523: Is the same: one or two sporoplasts , which are the real infectious agent, surrounded by a layer of flattened cells called valve cells , which can secrete a layer protective coating and form float appendages . Integrated into the layer of valve cells are two to four specialized capsulogenic cells (in a few cases, one or even 15), each carrying a polar capsule containing coiled polar filaments , an extrudable organelle used for recognition, contact and infiltration. Myxospores are ingested by annelids, in which

738-1565: The polypodiozoa , shared their last common ancestor with medusazoans about 600 million years ago, during the Ediacaran period. Myxozoan taxonomy has undergone great and important changes in its levels of generic, family and suborder classification. Fiala et al. (2015) proposed a new classification based on spores. Genus: Buddenbrockia, Tetracapsuloides Genus: Sphaeromyxa Genus: Myxidium, Zschokkella, Enteromyxum, Sigmomyxa, Soricimyxum, Cystodiscus Genus: Ortholinea, Neomyxobolus, Cardimyxobolus, Triangula, Kentmoseria Genus: Sinuolinea, Myxodavisia, Myxoproteus, Bipteria, Paramyxoproteus, Neobipteria, Schulmania, Noblea, Latyspora Genus: Fabespora Genus: Ceratomyxa, Meglitschia, Ellipsomyxa, Ceratonova Genus: Sphaerospora, Wardia, Palliatus Genus: Myxobilatus, Acauda, Hoferellus Genus: Chloromyxum, Caudomyxum, Agarella Genus: Coccomyxa, Auerbachia, Globospora Genus: Alatospora, Pseudalatospora, Renispora Genus: Parvicapsula, Neoparvicapsula, Gadimyxa Genus: Myxobolus, Spirosuturia, Unicauda, Dicauda, Phlogospora, Laterocaudata, Henneguya, Hennegoides, Tetrauronema, Thelohanellus, Neothelohanellus, Neohenneguya, Trigonosporus Genus: Trilospora, Unicapsula Genus: Kudoa Genus: Octospina   incertae sedis :       Trilosporoides       . . .      Etymology For languages with

779-518: The Latin word candidus , which means ' white ' , is the etymon of English candid . Relationships are often less transparent, however. English place names such as Winchester , Gloucester , Tadcaster share in different modern forms a suffixed etymon that was once meaningful, Latin castrum ' fort ' . Reflex is the name given to a descendant word in a daughter language, descended from an earlier language. For example, Modern English heat

820-462: The clade as severely modified members of the phylum Cnidaria , with medusozoans as their closest relatives. Similarities between myxozoan polar capsules and cnidarian nematocysts had been drawn for a long time, but were generally assumed to be the result of convergent evolution . Taxonomists now recognize the outdated subgroup Actinosporea as a life-cycle phase of Myxosporea . Molecular clocks suggest that myxozoans and their closest relatives,

861-423: The commercial fish industry, largely as a result of aquaculture bringing new species into contact with myxosporeans to which they had not been previously exposed, and to which they are highly susceptible. The economic impact of such parasites can be severe, especially where prevalence rates are high; they may also have a severe impact on wild fish stocks. The diseases caused by myxosporeas in cultured fish with

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902-475: The discovery that myxozoans are cnidarians. These cnidocysts fire tubules as in other cnidarians; some inject substances into the host. However, the tubules lack hooks or barbs, and in some species are more elastic than in other cnidarians. Myxozoans have secondarily lost epithelial structures, a nervous system , gut , and cilia . Most lack muscles , though these are retained in some members of malacosporea . Those who have lost their muscles move around inside

943-418: The documented cases, involve an intermediate host , usually a fish, but in rare cases amphibians, reptiles, birds, and mammals; and a definitive host, usually an annelid or an ectoproct . Only about 100 life cycles have been resolved and it is suspected that there may be some exclusively terrestrial. The mechanism of infection occurs through valve spores that have many forms, but their main morphology

984-477: The final site of infection, they produce mature spores within mono- or di-sporic pseudoplasmodia , or poly-sporic plasmodia . Relationships between myxosporeans and their hosts are often highly evolved and do not usually result in severe diseases of the natural host. Infection in fish hosts can be extremely long-lasting, potentially persisting for the lifetime of the host. However, an increasing number of myxosporeans have become pathogens with significant impact to

1025-535: The first three previously identified discrepant HOX genes ( Myx1-3 ) to the bryozoan Cristatella mucedo and the fourth ( Myx4 ) to northern pike , the respective hosts of the two corresponding Myxozoa samples. This explained the confusion: the original experiments had used samples contaminated by tissue from host organisms, leading to false positives for a position among the Bilateria. More careful cloning of 50 coding genes from Buddenbrockia firmly established

1066-448: The first to make a comprehensive analysis of linguistics and etymology. The study of Sanskrit etymology has provided Western scholars with the basis of historical linguistics and modern etymology. Four of the most famous Sanskrit linguists are: These linguists were not the earliest Sanskrit grammarians, however. They followed a line of ancient grammarians of Sanskrit who lived several centuries earlier like Sakatayana of whom very little

1107-561: The group Sporozoa . As their distinct nature became clear through 18S ribosomal DNA (rDNA) sequencing, they were relocated in the metazoa . Detailed classification within the metazoa was however long hindered by conflicting rDNA evidence: although 18S rDNA suggested an affinity with Cnidaria , other rDNA sampled, and the HOX genes of two species, were more similar to those of the Bilateria . The discovery that Buddenbrockia plumatellae ,

1148-446: The host using other forms of locomotion, such as the use of filopodia , spore valve contractions, amoeboid movements, and rapidly creating and reabsorbing folds on the cell membrane. Myxozoans do not undergo embryogenesis during development and have lost true gametes . Instead, they reproduce via multicellular spores. These spores contain the polar capsules, which are not typically present in somatic cells. Centrioles are not involved in

1189-661: The most significant economic impact worldwide are proliferative kidney disease (PKD) caused by the malacosporean T. bryosalmonae , and whirling disease , caused by a myxosporean M. cerebralis ; both diseases affect salmon . Enteromyxosis is caused by E. leei in cultured marine sparids , while proliferative gill disease (or “hamburger disease”) is caused by H. ictaluri in catfish and S. renicola infections occur in common carp . Myxozoans are very small animals, typically 10–300  μm in length. Like other cnidarians they possess cnidocysts , which were referred to as "polar capsules" before

1230-476: The nuclear division of myxozoans. Cell division by binary fission is rare, and cells divide instead via endogeny . In 2020, the myxozoan Henneguya salminicola was found to lack a mitochondrial genome , and thus be incapable of aerobic respiration ; it was the first animal to be positively identified as such. Its actual metabolism is currently unknown. Myxozoans were originally considered to be protozoans , and were included among other non-motile forms in

1271-426: The obvious, and actual "bridge-builder": The priests, called Pontifices.... have the name of Pontifices from potens , powerful because they attend the service of the gods, who have power and command overall. Others make the word refer to exceptions of impossible cases; the priests were to perform all the duties possible; if anything lays beyond their power, the exception was not to be cavilled. The most common opinion

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1312-416: The polar filaments extrude to anchor the spore to the gut epithelium . Opening of the shell valves allows the sporoplasms to penetrate into the epithelium. Subsequently, the parasite undergoes reproduction and development in the gut tissue, and finally produces usually eight actinosporean spore stages (actinospores) within a pansporocyst . After mature actinospores are released from their hosts they float in

1353-433: The practice of counting the recitation of prayers by using beads. The search for meaningful origins for familiar or strange words is far older than the modern understanding of linguistic evolution and the relationships of languages, which began no earlier than the 18th century. From Antiquity through the 17th century, from Pāṇini to Pindar to Sir Thomas Browne , etymology had been a form of witty wordplay, in which

1394-460: The relationship between two languages on the basis of similarity of grammar and lexicon was made in 1770 by the Hungarian, János Sajnovics , when he attempted to demonstrate the relationship between Sami and Hungarian (work that was later extended to the whole Finno-Ugric language family in 1799 by his fellow countryman, Samuel Gyarmathi ). The origin of modern historical linguistics

1435-477: The root word. For example unhappy , happily , and unhappily are all derivatives of the root word happy . The terms root and derivative are used in the analysis of morphological derivation within a language in studies that are not concerned with historical linguistics and that do not cross the language barrier. Etymologists apply a number of methods to study the origins of words, some of which are: Etymological theory recognizes that words originate through

1476-510: The saint's name: Lucy is said of light, and light is beauty in beholding, after that S. Ambrose saith: The nature of light is such, she is gracious in beholding, she spreadeth over all without lying down, she passeth in going right without crooking by right long line; and it is without dilation of tarrying, and therefore it is showed the blessed Lucy hath beauty of virginity without any corruption; essence of charity without disordinate love; rightful going and devotion to God, without squaring out of

1517-408: The sixteenth century. Etymologicum genuinum is a grammatical encyclopedia edited at Constantinople in the ninth century, one of several similar Byzantine works. The thirteenth-century Legenda Aurea , as written by Jacobus de Varagine , begins each vita of a saint with a fanciful excursus in the form of an etymology. The Sanskrit linguists and grammarians of ancient India were

1558-543: The supposed origins of words were creatively imagined to satisfy contemporary requirements; for example, the Greek poet Pindar (born in approximately 522 BCE) employed inventive etymologies to flatter his patrons. Plutarch employed etymologies insecurely based on fancied resemblances in sounds . Isidore of Seville 's Etymologiae was an encyclopedic tracing of "first things" that remained uncritically in use in Europe until

1599-416: The water column. Upon contact with skin or gills of fish, sporoplasms penetrate through the epithelium, followed by development of the myxosporean stage. Myxosporean trophozoites are characterized by cell-in-cell state, where the secondary (daughter) cells develop in the mother (primary) cells. The presporogonic stages multiply, migrate via nervous or circulatory systems, and develop into sporogonic stages. At

1640-464: The way; right long line by continual work without negligence of slothful tarrying. In Lucy is said, the way of light. Etymology in the modern sense emerged in the late 18th-century European academia, within the context of the wider " Age of Enlightenment ", although preceded by 17th century pioneers such as Marcus Zuerius van Boxhorn , Gerardus Vossius , Stephen Skinner , Elisha Coles , and William Wotton . The first known systematic attempt to prove

1681-691: The words of the sacred Vedas contained deep encoding of the mysteries of the soul and God. One of the earliest philosophical texts of the Classical Greek period to address etymology was the Socratic dialogue Cratylus ( c.  360 BCE ) by Plato . During much of the dialogue, Socrates makes guesses as to the origins of many words, including the names of the gods. In his Odes Pindar spins complimentary etymologies to flatter his patrons. Plutarch ( Life of Numa Pompilius ) spins an etymology for pontifex , while explicitly dismissing

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