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81-426: (see text ) The nematodes ( / ˈ n ɛ m ə t oʊ d z / NEM -ə-tohdz or NEEM - ; Ancient Greek : Νηματώδη ; Latin : Nematoda ), roundworms or eelworms constitute the phylum Nematoda . They are a diverse animal phylum inhabiting a broad range of environments. Most species are free-living, feeding on microorganisms , but many species are parasitic . The parasitic worms ( helminths ) are

162-537: A pitch accent . In Modern Greek, all vowels and consonants are short. Many vowels and diphthongs once pronounced distinctly are pronounced as /i/ ( iotacism ). Some of the stops and glides in diphthongs have become fricatives , and the pitch accent has changed to a stress accent . Many of the changes took place in the Koine Greek period. The writing system of Modern Greek, however, does not reflect all pronunciation changes. The examples below represent Attic Greek in

243-452: A characteristically bent or fan-shaped tail. During copulation , one or more chitinized spicules move out of the cloaca and are inserted into the genital pore of the female. Amoeboid sperm crawl along the spicule into the female worm. Nematode sperm is thought to be the only eukaryotic cell without the globular protein G-actin . Eggs may be embryonated or unembryonated when passed by

324-455: A collaborative wiki called 959 Nematode Genomes is underway to improve the systematics of this phylum. An analysis of the mitochondrial DNA suggests that the following groupings are valid In 2022 a new classification of the entire phylum Nematoda was presented by M. Hodda. It was based on current molecular, developmental and morphological evidence. Under this classification, the following classes and subclasses are presented: Nematode eggs from

405-481: A genetically determined correlation between DNA repair capacity and lifespan. In female C. elegans , germline processes that control DNA repair and formation of chromosomal crossovers during meiosis were shown to progressively deteriorate with age. Different free-living species feed on materials as varied as bacteria , algae , fungi , small animals, fecal matter, dead organisms, and living tissues. Free-living marine nematodes are important and abundant members of

486-533: A glandular and muscular ejaculatory duct associated with the vas deferens and cloaca . In females, the ovaries each open into an oviduct (in hermaphrodites, the eggs enter a spermatheca first) and then a glandular uterus . The uteri both open into a common vulva/vagina, usually located in the middle of the morphologically ventral surface. Reproduction is usually sexual, though hermaphrodites are capable of self-fertilization. Males are usually smaller than females or hermaphrodites (often much smaller) and often have

567-472: A lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period. They have the same general outline but differ in some of the detail. The only attested dialect from this period is Mycenaean Greek , but its relationship to the historical dialects and

648-443: A large ventral, a smaller dorsal and two pairs of sublateral cords extend posteriorly. Each nerve lies within a cord of connective tissue lying beneath the cuticle and between the muscle cells. The ventral nerve is the largest, and has a double structure forward of the excretory pore . The dorsal nerve is responsible for motor control, while the lateral nerves are sensory, and the ventral combines both functions. The nervous system

729-419: A lesser degree. Pamphylian Greek , spoken in a small area on the southwestern coast of Anatolia and little preserved in inscriptions, may be either a fifth major dialect group, or it is Mycenaean Greek overlaid by Doric, with a non-Greek native influence. Regarding the speech of the ancient Macedonians diverse theories have been put forward, but the epigraphic activity and the archaeological discoveries in

810-500: A pore on the underside of the animal, close to the pharynx. In most other nematodes, these specialized cells have been replaced by an organ consisting of two parallel ducts connected by a single transverse duct. This transverse duct opens into a common canal that runs to the excretory pore. At the anterior end of the animal a dense, circular nerve ring which serves as the brain surrounds the pharynx. From this ring six labial papillary nerve cords extend anteriorly, while six nerve cords;

891-543: A prefix /e-/, called the augment . This was probably originally a separate word, meaning something like "then", added because tenses in PIE had primarily aspectual meaning. The augment is added to the indicative of the aorist, imperfect, and pluperfect, but not to any of the other forms of the aorist (no other forms of the imperfect and pluperfect exist). The two kinds of augment in Greek are syllabic and quantitative. The syllabic augment

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972-410: A range of reproductive modes, including sexual reproduction , facultative sexuality (in which most, but not all, generations reproduce asexually), and both meiotic and mitotic parthenogenesis . The genus Mesorhabditis exhibits an unusual form of parthenogenesis, in which sperm-producing males copulate with females, but the sperm do not fuse with the ovum. Contact with the sperm is essential for

1053-671: A separate historical stage, though its earliest form closely resembles Attic Greek , and its latest form approaches Medieval Greek , and Koine may be classified as Ancient Greek in a wider sense. There were several regional dialects of Ancient Greek; Attic Greek developed into Koine. Ancient Greek was a pluricentric language , divided into many dialects. The main dialect groups are Attic and Ionic , Aeolic , Arcadocypriot , and Doric , many of them with several subdivisions. Some dialects are found in standardized literary forms in literature , while others are attested only in inscriptions. There are also several historical forms. Homeric Greek

1134-609: A standard subject of study in educational institutions of the Western world since the Renaissance . This article primarily contains information about the Epic and Classical periods of the language, which are the best-attested periods and considered most typical of Ancient Greek. From the Hellenistic period ( c.  300 BC ), Ancient Greek was followed by Koine Greek , which is regarded as

1215-426: A synonym. However, in 1910, Grobben proposed the phylum Aschelminthes and the nematodes were included as class Nematoda along with class Rotifera, class Gastrotricha, class Kinorhyncha, class Priapulida, and class Nematomorpha (The phylum was later revived and modified by Libbie Henrietta Hyman in 1951 as Pseudoceolomata, but remained similar). In 1932, Potts elevated the class Nematoda to the level of phylum, leaving

1296-510: A vowel or /n s r/ ; final stops were lost, as in γάλα "milk", compared with γάλακτος "of milk" (genitive). Ancient Greek of the classical period also differed in both the inventory and distribution of original PIE phonemes due to numerous sound changes, notably the following: The pronunciation of Ancient Greek was very different from that of Modern Greek . Ancient Greek had long and short vowels ; many diphthongs ; double and single consonants; voiced, voiceless, and aspirated stops ; and

1377-583: Is Bursaphelenchus xylophilus , the pine wood nematode, present in Asia and America and recently discovered in Europe. This nematode is transmitted from tree to tree by sawyer beetles ( Monochamus ). Ancient Greek language Ancient Greek ( Ἑλληνῐκή , Hellēnikḗ ; [hellɛːnikɛ́ː] ) includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It

1458-442: Is a lethal parasite of gastropods such as slugs and snails . Some members of the genus Steinernema such as Steinernema carpocapsae and Steinernema riobrave are generalist parasites of webworms , cutworms , armyworms , girdlers , some weevils , wood-borers and corn earworm moths . These organisms are grown commercially as biological pest control agents which can be used as an alternative to pesticides ; their use

1539-556: Is a literary form of Archaic Greek (derived primarily from Ionic and Aeolic) used in the epic poems , the Iliad and the Odyssey , and in later poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic and other Classical-era dialects. The origins, early form and development of the Hellenic language family are not well understood because of

1620-418: Is added to stems beginning with consonants, and simply prefixes e (stems beginning with r , however, add er ). The quantitative augment is added to stems beginning with vowels, and involves lengthening the vowel: Some verbs augment irregularly; the most common variation is e → ei . The irregularity can be explained diachronically by the loss of s between vowels, or that of the letter w , which affected

1701-531: Is also the only place in the nematode body that contains cilia , which are all nonmotile and with a sensory function. The bodies of nematodes are covered in numerous sensory bristles and papillae that together provide a sense of touch. Behind the sensory bristles on the head lie two small pits, or ' amphids '. These are well supplied with nerve cells and are probably chemoreception organs. A few aquatic nematodes possess what appear to be pigmented eye-spots, but whether or not these are actually sensory in nature

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1782-644: Is called 'East Greek'. Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian Greek had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect, as exemplified in the poems of the Boeotian poet Pindar who wrote in Doric with a small Aeolic admixture. Thessalian likewise had come under Northwest Greek influence, though to

1863-448: Is considered by some linguists to have been closely related to Greek . Among Indo-European branches with living descendants, Greek is often argued to have the closest genetic ties with Armenian (see also Graeco-Armenian ) and Indo-Iranian languages (see Graeco-Aryan ). Ancient Greek differs from Proto-Indo-European (PIE) and other Indo-European languages in certain ways. In phonotactics , ancient Greek words could end only in

1944-558: Is considered very safe. Plant-parasitic nematodes include several groups causing severe crop losses, taking 10% of crops worldwide every year. The most common genera are Aphelenchoides ( foliar nematodes ), Ditylenchus , Globodera (potato cyst nematodes), Heterodera (soybean cyst nematodes), Longidorus , Meloidogyne ( root-knot nematodes ), Nacobbus , Pratylenchus (lesion nematodes), Trichodorus , and Xiphinema (dagger nematodes). Several phytoparasitic nematode species cause histological damages to roots, including

2025-459: Is often found at the tip of the tail. The epidermis is either a syncytium or a single layer of cells, and is covered by a thick collagenous cuticle . The cuticle is often of a complex structure and may have two or three distinct layers. Underneath the epidermis lies a layer of longitudinal muscle cells. The relatively rigid cuticle works with the muscles to create a hydroskeleton, as nematodes lack circumferential muscles. Projections run from

2106-446: Is often ornamented with ridges, rings, bristles, or other distinctive structures. The head of a nematode is relatively distinct. Whereas the rest of the body is bilaterally symmetrical, the head is radially symmetrical, with sensory bristles and, in many cases, solid 'head-shields' radiating outwards around the mouth. The mouth has either three or six lips, which often bear a series of teeth on their inner edges. An adhesive 'caudal gland'

2187-546: Is often roughly divided into the following periods: Mycenaean Greek ( c.  1400–1200 BC ), Dark Ages ( c.  1200–800 BC ), the Archaic or Epic period ( c.  800–500 BC ), and the Classical period ( c.  500–300 BC ). Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers . It has contributed many words to English vocabulary and has been

2268-402: Is present, with the pharynx connecting directly to a muscleless intestine that forms the main length of the gut. This produces further enzymes and also absorbs nutrients through its single-cell-thick lining. The last portion of the intestine is lined by a cuticle, forming a rectum , which expels waste through the anus just below and in front of the tip of the tail. The movement of food through

2349-454: Is unclear. Most nematode species are dioecious , with separate male and female individuals, though some, such as Caenorhabditis elegans , are androdioecious , consisting of hermaphrodites and rare males. Both sexes possess one or two tubular gonads . In males, the sperm are produced at the end of the gonad and migrate along its length as they mature. The testis opens into a relatively wide seminal vesicle and then during intercourse into

2430-698: The Greek region of Macedonia during the last decades has brought to light documents, among which the first texts written in Macedonian , such as the Pella curse tablet , as Hatzopoulos and other scholars note. Based on the conclusions drawn by several studies and findings such as Pella curse tablet , Emilio Crespo and other scholars suggest that ancient Macedonian was a Northwest Doric dialect , which shares isoglosses with its neighboring Thessalian dialects spoken in northeastern Thessaly . Some have also suggested an Aeolic Greek classification. The Lesbian dialect

2511-530: The Moltrasio Formation , and the Rhynie chert , where the earliest known fossils are known from. Nematodes are very small, slender worms: typically about 5 to 100 μm thick, and 0.1 to 2.5 mm long. The smallest nematodes are microscopic, while free-living species can reach as much as 5 cm (2 in), and some parasitic species are larger still, reaching over 1 m (3 ft) in length. The body

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2592-831: The Monhysterida representing a very ancient minor group of nematodes. Among the Secernentea, the Diplogasteria may need to be united with the Rhabditia , while the Tylenchia might be paraphyletic with the Rhabditia. The understanding of roundworm systematics and phylogeny as of 2002 is summarised below: Phylum Nematoda Later work has suggested the presence of 12 clades. The Secernentea—a group that includes virtually all major animal and plant 'nematode' parasites—apparently arose from within

2673-533: The Vermes . The name of the group Nematoda, informally called "nematodes", came from Nematoidea , originally defined by Karl Rudolphi (1808), from Ancient Greek νῆμα ( nêma, nêmatos , 'thread') and -ειδἠς ( -eidēs , 'species'). It was treated as family Nematodes by Burmeister (1837). At its origin, the "Nematoidea" erroneously included Nematodes and Nematomorpha , attributed by von Siebold (1843). Along with Acanthocephala , Trematoda , and Cestoidea , it formed

2754-453: The clades Ascaridina, Spirurina, and Trichocephalida have been discovered in coprolites from the Oligocene -aged Tremembé Formation, which represented a palaeolake in present-day São Paulo with a diverse fossil assemblage of birds, fish, and arthropods that lent itself to fostering high nematode diversity. Nematodes have also been found in various lagerstätten , such as Burmese amber ,

2835-651: The meiobenthos . They play an important role in the decomposition process, aid in recycling of nutrients in marine environments, and are sensitive to changes in the environment caused by pollution. One roundworm of note, C. elegans , lives in the soil and has found much use as a model organism . C. elegans has had its entire genome sequenced, the developmental fate of every cell determined, and every neuron mapped. Nematodes that commonly parasitise humans include ascarids ( Ascaris ), filarias , hookworms , pinworms ( Enterobius ), and whipworms ( Trichuris trichiura ). The species Trichinella spiralis , commonly known as

2916-501: The present , future , and imperfect are imperfective in aspect; the aorist , present perfect , pluperfect and future perfect are perfective in aspect. Most tenses display all four moods and three voices, although there is no future subjunctive or imperative. Also, there is no imperfect subjunctive, optative or imperative. The infinitives and participles correspond to the finite combinations of tense, aspect, and voice. The indicative of past tenses adds (conceptually, at least)

2997-411: The uterus until they hatch. The juvenile nematodes then ingest the parent nematode. This process is significantly promoted in environments with a low food supply. The nematode model species C. elegans , C. briggsae , and Pristionchus pacificus , among other species, exhibit androdioecy , which is otherwise very rare among animals. The single genus Meloidogyne (root-knot nematodes) exhibits

3078-1031: The 5th century BC. Ancient pronunciation cannot be reconstructed with certainty, but Greek from the period is well documented, and there is little disagreement among linguists as to the general nature of the sounds that the letters represent. /oː/ raised to [uː] , probably by the 4th century BC. Greek, like all of the older Indo-European languages , is highly inflected. It is highly archaic in its preservation of Proto-Indo-European forms. In ancient Greek, nouns (including proper nouns) have five cases ( nominative , genitive , dative , accusative , and vocative ), three genders ( masculine , feminine , and neuter ), and three numbers (singular, dual , and plural ). Verbs have four moods ( indicative , imperative , subjunctive , and optative ) and three voices (active, middle, and passive ), as well as three persons (first, second, and third) and various other forms. Verbs are conjugated through seven combinations of tenses and aspect (generally simply called "tenses"):

3159-557: The Adenophorea were not in a uniform group. Initial studies of incomplete DNA sequences suggested the existence of five clades : The Secernentea seem to be a natural group of close relatives, while the "Adenophorea" appear to be a paraphyletic assemblage of roundworms that retain a good number of ancestral traits . The old Enoplia do not seem to be monophyletic, either, but do contain two distinct lineages. The old group " Chromadoria " seems to be another paraphyletic assemblage, with

3240-453: The Adenophorea. In 2019, a study identified one conserved signature indel (CSI) found exclusively in members of the phylum Nematoda through comparative genetic analyses. The CSI consists of a single amino acid insertion within a conserved region of a Na(+)/H(+) exchange regulatory factor protein NRFL-1 and is a molecular marker that distinguishes the phylum from other species. A major effort by

3321-490: The Archaic period of ancient Greek (see Homeric Greek for more details): Μῆνιν ἄειδε, θεά, Πηληϊάδεω Ἀχιλῆος οὐλομένην, ἣ μυρί' Ἀχαιοῖς ἄλγε' ἔθηκε, πολλὰς δ' ἰφθίμους ψυχὰς Ἄϊδι προΐαψεν ἡρώων, αὐτοὺς δὲ ἑλώρια τεῦχε κύνεσσιν οἰωνοῖσί τε πᾶσι· Διὸς δ' ἐτελείετο βουλή· ἐξ οὗ δὴ τὰ πρῶτα διαστήτην ἐρίσαντε Ἀτρεΐδης τε ἄναξ ἀνδρῶν καὶ δῖος Ἀχιλλεύς. The beginning of Apology by Plato exemplifies Attic Greek from

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3402-603: The Classical period of ancient Greek. (The second line is the IPA , the third is transliterated into the Latin alphabet using a modern version of the Erasmian scheme .) Ὅτι [hóti Hóti μὲν men mèn ὑμεῖς, hyːmêːs hūmeîs,   Vermes In Linnaeus's Systema Naturae , the Vermes had the rank of class , occupying the 6th (and last) slot of his animal systematics. It

3483-591: The Introverta—depending on the validity of the former—are often ranked as a superphylum . For an up-to-date view (as of 2022), see Phylogenomic Analysis of the Phylum Nematoda: Conflicts and Congruences With Morphology, 18S rRNA, and Mitogenomes . Due to the lack of knowledge regarding many nematodes, their systematics is contentious. An early and influential classification was proposed by Chitwood and Chitwood—later revised by Chitwood—who divided

3564-675: The Nematoda has always been considered to be well resolved. Morphological characters and molecular phylogenies agree with placement of the roundworms as a sister taxon to the parasitic Nematomorpha ; together, they make up the Nematoida . Along with the Scalidophora (formerly Cephalorhyncha), the Nematoida form the clade Cycloneuralia , but much disagreement occurs both between and among the available morphological and molecular data. The Cycloneuralia or

3645-483: The Testacea, together with barnacles and tube worms . Cnidarians (jellyfish and corals), echinoderms and polychaetes were spread across the other orders. Linnaeus's system was revised by Jean-Baptiste Lamarck in his 1801 Système des Animaux sans Vertebres . In this work, he categorized echinoderms , arachnids , crustaceans and annelids , which he separated from Vermes . After Linnaeus, and especially with

3726-421: The advent of Darwinism , it became apparent that the Vermes animals are not closely related. Systematic works on phyla since Linnaeus continued to split up Vermes and sort the animals into natural systematic units. Of the classes of Vermes proposed by Linnaeus, only Mollusca has been kept as a phylum, and its composition has changed almost entirely. Linnaeus's early classification of the soft-bodied organisms

3807-626: The ancestral protostome Hox genotype, which shows that the reduction has occurred within the nematode phylum. Nematode species can be difficult to distinguish from one another. Consequently, estimates of the number of nematode species are uncertain. A 2013 survey of animal biodiversity published in the mega journal Zootaxa puts this figure at over 25,000. Estimates of the total number of extant species are subject to even greater variation. A widely referenced article published in 1993 estimated there may be over 1 million species of nematode. A subsequent publication challenged this claim, estimating

3888-406: The animal can thrust into its prey. In some species, the style is hollow and can be used to suck liquids from plants or animals. The oral cavity opens into a muscular, sucking pharynx , also lined with cuticle. Digestive glands are found in this region of the gut, producing enzymes that start to break down the food. In stylet-bearing species, these may even be injected into the prey. No stomach

3969-550: The aorist. Following Homer 's practice, the augment is sometimes not made in poetry , especially epic poetry. The augment sometimes substitutes for reduplication; see below. Almost all forms of the perfect, pluperfect, and future perfect reduplicate the initial syllable of the verb stem. (A few irregular forms of perfect do not reduplicate, whereas a handful of irregular aorists reduplicate.) The three types of reduplication are: Irregular duplication can be understood diachronically. For example, lambanō (root lab ) has

4050-419: The augment when it was word-initial. In verbs with a preposition as a prefix, the augment is placed not at the start of the word, but between the preposition and the original verb. For example, προσ(-)βάλλω (I attack) goes to προσ έ βαλoν in the aorist. However compound verbs consisting of a prefix that is not a preposition retain the augment at the start of the word: αὐτο(-)μολῶ goes to ηὐ τομόλησα in

4131-463: The bee less active, thus less effective in pollen collection. Depending on its species, a nematode may be beneficial or detrimental to plant health. From agricultural and horticulture perspectives, the two categories of nematodes are the predatory ones, which kill garden pests; and the pest nematodes, which attack plants, or act as vectors spreading plant viruses between crop plants. Predatory nematodes include Phasmarhabditis hermaphrodita which

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4212-402: The cause of soil-transmitted helminthiases . They are taxonomically classified along with arthropods , tardigrades and other moulting animals in the clade Ecdysozoa . Unlike the vaguely similar flatworms , nematodes have a tubular digestive system , with openings at both ends. Like tardigrades, they have a reduced number of Hox genes , but their sister phylum Nematomorpha has kept

4293-438: The center of Greek scholarship, this division of people and language is quite similar to the results of modern archaeological-linguistic investigation. One standard formulation for the dialects is: West vs. non-West Greek is the strongest-marked and earliest division, with non-West in subsets of Ionic-Attic (or Attic-Ionic) and Aeolic vs. Arcadocypriot, or Aeolic and Arcado-Cypriot vs. Ionic-Attic. Often non-West

4374-611: The dialect of Sparta ), and Northern Peloponnesus Doric (including Corinthian ). All the groups were represented by colonies beyond Greece proper as well, and these colonies generally developed local characteristics, often under the influence of settlers or neighbors speaking different Greek dialects. After the conquests of Alexander the Great in the late 4th century BC, a new international dialect known as Koine or Common Greek developed, largely based on Attic Greek , but with influence from other dialects. This dialect slowly replaced most of

4455-493: The digestive system is the result of the body movements of the worm. The intestine has valves or sphincters at either end to help control food movement through the body. Nitrogenous waste is excreted in the form of ammonia through the body wall, and is not associated with any specific organs. However, the structures for excreting salt to maintain osmoregulation are typically more complex. In many marine nematodes, one or two unicellular ' renette glands ' excrete salt through

4536-442: The eggshell is complicated and includes several layers; a detailed anatomical and terminological framework has been proposed for these layers in 2023. Nematodes as a whole possess a wide range of modes of reproduction. Some nematodes, such as Heterorhabditis spp., undergo a process called endotokia matricida : intrauterine birth causing maternal death. Some nematodes are hermaphroditic , and keep their self-fertilized eggs inside

4617-425: The female, meaning their fertilized eggs may not yet be developed. A few species are known to be ovoviviparous . The eggs are protected by an outer shell, secreted by the uterus. In free-living roundworms, the eggs hatch into larvae , which appear essentially identical to the adults, except for an underdeveloped reproductive system; in parasitic roundworms, the lifecycle is often much more complicated. The structure of

4698-473: The figure to be at least 40,000 species. Although the highest estimates (up to 100 million species) have since been deprecated, estimates supported by rarefaction curves , together with the use of DNA barcoding and the increasing acknowledgment of widespread cryptic species among nematodes, have placed the figure closer to 1 million species. Nematodes have successfully adapted to nearly every ecosystem : from marine (salt) to fresh water, soils, from

4779-400: The first used term in case of synonyms. The phylogenetic relationships of the nematodes and their close relatives among the protostomian Metazoa are unresolved. Traditionally, they were held to be a lineage of their own, but in the 1990s, they were proposed to form the group Ecdysozoa together with moulting animals, such as arthropods . The identity of the closest living relatives of

4860-490: The formation of visible galls (e.g. by root-knot nematodes), which are useful characters for their diagnostic in the field. Some nematode species transmit plant viruses through their feeding activity on roots. One of them is Xiphinema index , vector of grapevine fanleaf virus , an important disease of grapes, another one is Xiphinema diversicaudatum , vector of arabis mosaic virus . Other nematodes attack bark and forest trees. The most important representative of this group

4941-466: The genera occur as parasites of vertebrates ; about 35 nematode species occur in humans. The word nematode comes from the Modern Latin compound of nemat- 'thread' (from Greek nema , genitive nematos 'thread', from the stem nein 'to spin'; cf. needle ) + -odes 'like, of the nature of' (cf. -oid ). In 1758, Linnaeus described some nematode genera (e.g., Ascaris ), then included in

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5022-556: The historical Dorians . The invasion is known to have displaced population to the later Attic-Ionic regions, who regarded themselves as descendants of the population displaced by or contending with the Dorians. The Greeks of this period believed there were three major divisions of all Greek people – Dorians, Aeolians, and Ionians (including Athenians), each with their own defining and distinctive dialects. Allowing for their oversight of Arcadian, an obscure mountain dialect, and Cypriot, far from

5103-472: The historical circumstances of the times imply that the overall groups already existed in some form. Scholars assume that major Ancient Greek period dialect groups developed not later than 1120 BC, at the time of the Dorian invasions —and that their first appearances as precise alphabetic writing began in the 8th century BC. The invasion would not be "Dorian" unless the invaders had some cultural relationship to

5184-449: The infected ants for berries, and eat them. Parasite eggs passed in the bird's feces are subsequently collected by foraging C. atratus and are fed to their larvae , thus completing the lifecycle of M. neotropicum . Similarly, multiple varieties of nematodes have been found in the abdominal cavities of the primitively social sweat bee, Lasioglossum zephyrus . Inside the female body, the nematode hinders ovarian development and renders

5265-417: The inner surface of muscle cells towards the nerve cords ; this is a unique arrangement in the animal kingdom, in which nerve cells normally extend fibers into the muscles rather than vice versa . The oral cavity is lined with cuticles, which are often strengthened with structures, such as ridges, especially in carnivorous species, which may bear several teeth. The mouth often includes a sharp stylet , which

5346-435: The name the same. Despite Potts' classification being equivalent to Cobbs', both names have been used (and are still used today) and Nematode became a popular term in zoological science. Since Cobb was the first to include nematodes in a particular phylum separated from Nematomorpha, some researchers consider the valid taxon name to be Nemates or Nemata, rather than Nematoda, because of the zoological rule that gives priority to

5427-459: The nemas and gordiids was realized by Vejdovsky when he named a group to contain the horsehair worms the order Nematomorpha. In 1919, Nathan Cobb proposed that nematodes should be recognized alone as a phylum. He argued they should be called "nema" in English rather than "nematodes" and defined the taxon Nemates (later emended as Nemata, Latin plural of nema ), listing Nematoidea sensu restricto as

5508-408: The obsolete group Entozoa , created by Rudolphi (1808). They were also classed along with Acanthocephala in the obsolete phylum Nemathelminthes by Gegenbaur (1859). In 1861, K. M. Diesing treated the group as order Nematoda. In 1877, the taxon Nematoidea, including the family Gordiidae (horsehair worms), was promoted to the rank of phylum by Ray Lankester . The first clear distinction between

5589-499: The older dialects, although the Doric dialect has survived in the Tsakonian language , which is spoken in the region of modern Sparta. Doric has also passed down its aorist terminations into most verbs of Demotic Greek . By about the 6th century AD, the Koine had slowly metamorphosed into Medieval Greek . Phrygian is an extinct Indo-European language of West and Central Anatolia , which

5670-489: The ovum to begin dividing, but because no fusion of the cells occurs, the male contributes no genetic material to the offspring, which are essentially clones of the female. The nematode Caenorhabditis elegans is often used as a model organism for studying aging at the molecular level. For example, in C. elegans aging negatively impacts DNA repair , and mutants of C. elegans that are long-lived were shown to have increased DNA repair capability. These findings suggest

5751-487: The perfect stem eilēpha (not * lelēpha ) because it was originally slambanō , with perfect seslēpha , becoming eilēpha through compensatory lengthening. Reduplication is also visible in the present tense stems of certain verbs. These stems add a syllable consisting of the root's initial consonant followed by i . A nasal stop appears after the reduplication in some verbs. The earliest extant examples of ancient Greek writing ( c.  1450 BC ) are in

5832-421: The phylum into two classes— Aphasmidia and Phasmidia . These were later renamed Adenophorea (gland bearers) and Secernentea (secretors), respectively. The Secernentea share several characteristics, including the presence of phasmids , a pair of sensory organs located in the lateral posterior region, and this was used as the basis for this division. This scheme was adhered to in many later classifications, though

5913-499: The polar regions to the tropics, as well as the highest to the lowest of elevations. They are ubiquitous in freshwater, marine, and terrestrial environments, where they often outnumber other animals in both individual and species counts, and are found in locations as diverse as mountains, deserts, and oceanic trenches . They are found in every part of the Earth's lithosphere , even at great depths, 0.9–3.6 km (3,000–12,000 ft) below

5994-824: The surface of the Earth in gold mines in South Africa. They represent 90% of all animals on the ocean floor . In total, 4.4 × 10 nematodes inhabit the Earth's topsoil, or approximately 60 billion for each human, with the highest densities observed in tundra and boreal forests. Their numerical dominance, often exceeding a million individuals per square meter and accounting for about 80% of all individual animals on Earth, their diversity of lifecycles, and their presence at various trophic levels point to an important role in many ecosystems. They have been shown to play crucial roles in polar ecosystems. The roughly 2,271  genera are placed in 256  families . The many parasitic forms include pathogens in most plants and animals. A third of

6075-517: The syllabic script Linear B . Beginning in the 8th century BC, however, the Greek alphabet became standard, albeit with some variation among dialects. Early texts are written in boustrophedon style, but left-to-right became standard during the classic period. Modern editions of ancient Greek texts are usually written with accents and breathing marks , interword spacing , modern punctuation , and sometimes mixed case , but these were all introduced later. The beginning of Homer 's Iliad exemplifies

6156-414: The trichina worm, occurs in rats, pigs, bears, and humans, and is responsible for the disease trichinosis . Baylisascaris usually infests wild animals, but can be deadly to humans, as well. Dirofilaria immitis is known for causing heartworm disease by inhabiting the hearts, arteries, and lungs of dogs and some cats. Haemonchus contortus is one of the most abundant infectious agents in sheep around

6237-452: The wasp, and their offspring await the birth of the next generation of wasps as the fig ripens. A parasitic tetradonematid nematode discovered in 2005, Myrmeconema neotropicum , induces fruit mimicry in the tropical ant Cephalotes atratus . Infected ants develop bright red gasters (abdomens), tend to be more sluggish, and walk with their gasters in a conspicuous elevated position. These changes likely cause frugivorous birds to confuse

6318-432: The world, causing great economic damage to sheep. In contrast, entomopathogenic nematodes parasitize insects and are mostly considered beneficial by humans, but some attack beneficial insects. One form of nematode is entirely dependent upon fig wasps , which are the sole source of fig fertilization. They prey upon the wasps, riding them from the ripe fig of the wasp's birth to the fig flower of its death, where they kill

6399-475: Was Aeolic. For example, fragments of the works of the poet Sappho from the island of Lesbos are in Aeolian. Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, or to an island. Doric notably had several intermediate divisions as well, into Island Doric (including Cretan Doric ), Southern Peloponnesus Doric (including Laconian ,

6480-590: Was divided into the following orders , all except the Lithophyta containing (in modern terms) organisms from a variety of phyla: Apart from the Mollusca , understood very differently from the modern phylum of that name, Linnaeus included a very diverse and rather mismatched assemblage of animals in the categories. The Intestina group encompassed various parasitic animals, among them the hagfish , which Linnaeus would have found in dead fish. Shelled molluscs were placed in

6561-426: Was revolutionary in its day. A number of the organisms classified as Vermes by Linnaeus were very poorly known, and a number of them were not even viewed as animals. While the Vermes is no longer a taxonomic group, anatomists continue to use the description "vermiform" of animals or organs that are worm -shaped. The word root is Latin , vermes ( worms ) and formes ( shaped ) . A well known example

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