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52-419: Hydrozoa ( hydrozoans ; from Ancient Greek ὕδωρ ( húdōr )  'water' and ζῷον ( zôion )  'animal') is a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water . The colonies of the colonial species can be large, and in some cases the specialized individual animals cannot survive outside

104-537: 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

156-415: A polypoid and a medusoid stage in their life cycles , although a number of them have only one or the other. For example, Hydra has no medusoid stage, while Liriope lacks the polypoid stage. The hydroid form is usually colonial, with multiple polyps connected by tubelike hydrocauli. The hollow cavity in the middle of the polyp extends into the associated hydrocaulus, so that all the individuals of

208-533: A consensus seems to be emerging. Historically, the hydrozoans were divided into a number of orders , according to their mode of growth and reproduction. Most famous among these was probably the assemblage called " Hydroida ", but this group is apparently paraphyletic , united by plesiomorphic (ancestral) traits. Other such orders were the Anthoathecatae , Actinulidae , Laingiomedusae , Polypodiozoa , Siphonophorae and Trachylina . As far as can be told from

260-481: A few colonial species have other specialized forms. In some, defensive polyps are found, armed with large numbers of stinging cells. In others, one polyp may develop as a large float, from which the other polyps hang down, allowing the colony to drift in open water instead of being anchored to a solid surface. The medusae of hydrozoans are smaller than those of typical jellyfish, ranging from 0.5 to 6 cm (0.20 to 2.36 in) in diameter. Although most hydrozoans have

312-472: 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

364-419: 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

416-408: A medusoid stage, this is not always free-living and in many species exists solely as a sexually reproducing bud on the surface of the hydroid colony. Sometimes, these medusoid buds may be so degenerated as to entirely lack tentacles or mouths, essentially consisting of an isolated gonad . The body consists of a dome-like umbrella ringed by tentacles. A tube-like structure hangs down from the centre of

468-406: A more or less cylindrical body with a terminal mouth on a raised protuberance called the hypostome , surrounded by a number of tentacles. The polyp contains a central cavity, in which initial digestion takes place. Partially digested food may then be passed into the hydrocaulus for distribution around the colony and completion of the digestion process. Unlike some other cnidarian groups, the lining of

520-543: 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

572-510: 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

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624-487: 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

676-556: 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

728-418: 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

780-644: 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

832-672: Is common in the developed world and this delay is often associated with ovarian female infertility and subfertility. Ovarian aging is characterized by progressive decline of the quality and number of oocytes . This decline is likely due, in part, to reduced expression of genes that encode proteins necessary for DNA repair and meiosis . Such reduced expression can lead to increased DNA damage and errors in meiotic recombination . The testes of older men often have sperm abnormalities that can ultimately lead to male infertility . These abnormalities include accumulation of DNA damage and decreased DNA repair ability. During spermatogenesis in

884-448: 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

936-616: Is often seen to reflect the uncertainties surrounding this highly distinct animal. Some of the more widespread classification systems for the Hydrozoa are listed below. Though they are often found in seemingly authoritative Internet sources and databases, they do not agree with the available data.Especially the presumed phylogenetic distinctness of the Siphonophorae is a major flaw that was corrected only recently. The obsolete classification mentioned above was: A very old classification that

988-513: Is sometimes still seen is: Catalogue of Life uses: Animal Diversity Web uses: 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 is often roughly divided into the following periods: Mycenaean Greek ( c.  1400–1200 BC ), Dark Ages ( c.  1200–800 BC ),

1040-658: 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 a standard subject of study in educational institutions of the Western world since the Renaissance . This article primarily contains information about

1092-537: 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 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

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1144-698: 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

1196-633: The SRY gene , located on the short arm of the Y chromosome and encoding the testis determining factor , usually determines male sexual differentiation. In the absence of the SRY gene from the Y chromosome, usually the female sex (ovaries instead of testes) will develop. The development of the gonads is a part of the development of the urinary and reproductive organs . The gonads are subject to many diseases, such as hypergonadism , hypogonadism , agonadism , tumors, and cancer, among others. A delay in having children

1248-525: The anterior pituitary gland . This secretion is regulated by gonadotropin-releasing hormone (GnRH) produced in the hypothalamus . The gonads develop from three sources; the mesothelium, underlying mesenchyme and the primordial germ cells. Gonads start developing as a common primordium (an organ in the earliest stage of development), in the form of genital ridges , at the sixth week, which are only later differentiated to male or female sex organs (except when they are not differentiated). The presence of

1300-578: The molecular and morphological data at hand, the Siphonophora for example were just highly specialized "hydroids," whereas the Limnomedusae —presumed to be a "hydroid" suborder —were simply very primitive hydrozoans and not closely related to the other "hydroids." So, the hydrozoans now are at least tentatively divided into two subclasses , the Leptolinae (containing the bulk of the former "Hydroida" and

1352-501: 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)

1404-1031: 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"):

1456-490: 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

1508-689: 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,   Gonad It is hard to find a common origin for gonads, but gonads most likely evolved independently several times. The gonads are controlled by luteinizing hormone (LH) and follicle-stimulating hormone (FSH), produced and secreted by gonadotropes or gonadotrophins in

1560-574: The Siphonophora) and the Trachylinae , containing the others (including the Limnomedusae). The monophyly of several of the presumed orders in each subclass is still in need of verification. In any case, according to this classification, the hydrozoans can be subdivided as follows, with taxon names emended to end in "-ae": Class Hydrozoa ITIS uses the same system, but unlike here, does not use

1612-465: The animals - they can transform themselves from sexually mature medusae stage back to their juvenile hydroid stage. The earliest hydrozoans may be from the Vendian (late Precambrian), more than 540 million years ago. Hydrozoan systematics are highly complex. Several approaches for expressing their interrelationships were proposed and heavily contested since the late 19th century, but in more recent times

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1664-550: 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

1716-419: 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

1768-420: The case of planulae), or swim and develop into another medusa or polyp directly (actinulae). Colonial hydrozoans include siphonophore colonies, Hydractinia , Obelia , and many others. In hydrozoan species with both polyp and medusa generations, the medusa stage is the sexually reproductive phase. Medusae of these species of Hydrozoa are known as "hydromedusae". Most hydromedusae have shorter lifespans than

1820-433: The case of the deep-sea Branchiocerianthus , a remarkable 2 m (6.6 ft). The hydrocaulus is usually surrounded by a sheath of chitin and proteins called the perisarc. In some species, this extends upwards to also enclose part of the polyps, in some cases including a closeable lid through which the polyp may extend its tentacles. In any given colony, the majority of polyps are specialized for feeding. These have

1872-438: 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

1924-444: The central cavity lacks stinging nematocysts , which are found only on the tentacles and outer surface. All colonial hydrozoans also include some polyps specialized for reproduction. These lack tentacles and contain numerous buds from which the medusoid stage of the life cycle is produced. The arrangement and type of these reproductive polyps varies considerably between different groups. In addition to these two basic types of polyps,

1976-518: The colony are intimately connected. Where the hydrocaulus runs along the substrate, it forms a horizontal root-like stolon that anchors the colony to the bottom. The colonies are generally small, no more than a few centimeters across, but some in Siphonophorae can reach sizes of several meters. They may have a tree-like or fan-like appearance, depending on species. The polyps themselves are usually tiny, although some noncolonial species are much larger, reaching 6 to 9 cm (2.4 to 3.5 in), or, in

2028-451: The colony. A few genera within this class live in freshwater habitats . Hydrozoans are related to jellyfish and corals and belong to the phylum Cnidaria . Some examples of hydrozoans are the freshwater jelly ( Craspedacusta sowerbyi ), freshwater polyps ( Hydra ), Obelia , Portuguese man o' war ( Physalia physalis ), chondrophores (Porpitidae), and pink-hearted hydroids ( Tubularia ). Most hydrozoan species include both

2080-611: 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

2132-556: 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

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2184-472: 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

2236-563: The larger scyphozoan jellyfish. Some species of hydromedusae release gametes shortly after they are themselves released from the hydroids (as in the case of fire corals ), living only a few hours, while other species of hydromedusae grow and feed in the plankton for months, spawning daily for many days before their supply of food or other water conditions deteriorate and cause their demise. Additionally, some hydrozoan species (particularly in Turritopsis genus) share an unusual life cycle among

2288-461: The muscles and tentacles. The genus Sarsia has even been reported to possess organised ganglia . Numerous sense organs are closely associated with the nerve rings. Mostly these are simple sensory nerve endings, but they also include statocysts and primitive light-sensitive ocelli . Hydroid colonies are usually dioecious , which means they have separate sexes—all the polyps in each colony are either male or female, but not usually both sexes in

2340-499: 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

2392-439: The oldest available names for many groups. In addition, there exists a cnidarian parasite , Polypodium hydriforme , which lives inside its host's cells . It is sometimes placed in the Hydrozoa, though its relationships are currently unresolved—a somewhat controversial 18S rRNA sequence analysis found it to be closer to the also parasitic Myxozoan . It was traditionally placed in its own class , Polypodiozoa, and this view

2444-487: 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

2496-408: The rim of the bell, allowing the animal to move along by alternately contracting and relaxing its body. An additional shelf of tissue lies just inside the rim, narrowing the aperture at the base of the umbrella, and thereby increasing the force of the expelled jet of water. The nervous system is unusually advanced for cnidarians. Two nerve rings lie close to the margin of the bell, and send fibres into

2548-402: The same colony. In some species, the reproductive polyps, known as gonozooids (or "gonotheca" in thecate hydrozoans ) bud off asexually produced medusae. These tiny, new medusae (which are either male or female) mature and spawn, releasing gametes freely into the sea in most cases. Zygotes become free-swimming planula larvae or actinula larvae that either settle on a suitable substrate (in

2600-517: 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

2652-416: The umbrella and includes the mouth at its tip. Most hydrozoan medusae have just four tentacles, although a number of exceptions exist. Stinging cells are found on the tentacles and around the mouth. The mouth leads into a central stomach cavity. Four radial canals connect the stomach to an additional, circular canal running around the base of the bell, just above the tentacles. Striated muscle fibres also line

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2704-475: 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 ,

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