74-508: See text The shipworms , also called Teredo worms or simply Teredo (from Ancient Greek τερηδών ( terēdṓn ) 'wood-worm', via Latin terēdō ), are marine bivalve molluscs in the family Teredinidae , a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into (and commonly eventually destroying) wood that is immersed in seawater , including such structures as wooden piers , docks , and ships; they drill passages by means of
148-543: 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
222-525: 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 the Greek region of Macedonia during the last decades has brought to light documents, among which the first texts written in Macedonian , such as
296-452: A meter in length, depending on the species. An average adult shipworm measures 4 to 6 inches (10 to 15 cm) in length and less than one-quarter inch (6.4 mm) in diameter, but some species grow to considerable size. The body is cylindrical, slender, naked, and superficially vermiform (worm-shaped). In spite of their slender, worm-like forms, shipworms possess the characteristic morphology of bivalves . The ctinidia lie mainly within
370-530: A navigable river. Henry David Thoreau 's poem "Though All the Fates" pays homage to "New England's worm" which, in the poem, infests the hull of "[t]he vessel, though her masts be firm". In time, no matter what the ship carries or where she sails, the shipworm "her hulk shall bore, / [a]nd sink her in the Indian seas". The hull of the ship wrecked by a whale, inspiring Moby Dick , had been weakened by shipworms. In
444-412: A pair of very small shells (" valves ") borne at one end, with which they rasp their way through. They are sometimes called "termites of the sea". Carl Linnaeus assigned the common name Teredo to the best-known genus of shipworms in the 10th edition of his taxonomic magnum opus , Systema Naturæ (1758). Removed from its burrow, the fully grown teredo ranges from several centimeters to about
518-550: 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
592-542: 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 a lesser degree. Pamphylian Greek , spoken in a small area on the southwestern coast of Anatolia and little preserved in inscriptions, may be either
666-413: A suitable location, where it attaches itself with a byssus thread. It may secrete an enzyme to soften the wood before starting to dig with its foot. When it has formed a hollow, it undergoes a rapid metamorphosis, shedding and consuming the velum and becoming a juvenile shipworm with small horny valves at the anterior end. It can then begin to dig more efficiently. It bores deeper into the wood and spends
740-510: 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
814-543: Is a very destructive pest of submerged timber. In the Baltic Sea , pine trees can become riddled with tunnels within 16 weeks of being in the water and oaks within 32 weeks, with whole trees 30 cm (12 in) in diameter being completely destroyed within a year. Ships' timbers are attacked, wrecks destroyed and sea defences damaged. Around 1730 in the Netherlands, shipworms were found to be seriously weakening
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#1732797508297888-418: 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
962-448: 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
1036-552: Is deadly to these invertebrates . Their ideal temperature range is 15 to 25 °C (59 to 77 °F) and therefore T. navalis can be found in temperate and tropical zones. The shipworm lives in waters with oceanic salinity . Accordingly, it is rare in the brackish Baltic Sea, where wooden shipwrecks are preserved for much longer than in the oceans. The range of various species has changed over time based on human activity. Many waters in developed countries that had been plagued by shipworms were cleared of them by pollution from
1110-430: Is found in temperate and tropical seas and oceans worldwide. It may have originated in the northeast Atlantic Ocean, but it is difficult to establish where it originally came from because it has spread so efficiently around the world on debris and hulls of ships. It is found in the littoral zone , living inside submerged timber, pilings, driftwood, and in the hulls of wooden boats. It is found in brackish waters as well as
1184-447: Is harvested, sold, and eaten from those taken by local natives in the mangrove forests of West Papua and some part of Borneo Island , Indonesia , and the central coastal peninsular regions of Thailand near Ko Phra Thong . T. navalis grow faster than any other bivalve because it does not require much energy to create its small shell. They can grow to be about 30 cm (12 in) long in just six months. Mussels and oysters , on
1258-433: Is not just the home of the black slimy worm. Instead, it acts as the primary source of nourishment in a non-traditional way. K. polythalamia sifts mud and sediment with its gills. Most shipworms are relatively smaller and feed on rotten wood. This shipworm instead relies on a beneficial symbiotic bacteria living in its gills. The bacteria use the hydrogen sulfide for energy to produce organic compounds that in turn feed
1332-402: Is referred to as tambelo and is considered as a delicacy in daily meals. It can be eaten fresh and raw (cleaned) or cooked (cleaned and boiled) as well and usually marinated with lime juice and chili peppers. Since T. navalis are related to clams , mussels , and oysters , the taste of the flesh has been compared to a wide variety of foods, from milk to oysters . Similarly, the delicacy
1406-543: Is the most commonly mentioned. The best known species is Teredo navalis . Historically, Teredo concentrations in the Caribbean Sea have been substantially higher than in most other salt water bodies. Genera within the family Teridinidae include: The Teredo genus has approximately 20 species that live in wooden materials such as logs, pilings, ship, and practically any other submerged wooden construction from temperate to tropical ocean zones. The species
1480-585: Is thought to be native to the Atlantic Ocean and was once known as the Atlantic shipworm, although its exact origin is unknown. The longest marine bivalve, Kuphus polythalamia , was found from a lagoon near Mindanao island in the southeastern part of the Philippines , which belongs to the same group of mussels and clams. The existence of huge mollusks was established for centuries and studied by
1554-404: Is usually lined with a calcareous tube. The valves of the shell of shipworms are small separate parts located at the anterior end of the worm, used for excavating the burrow. The protective role of the shells is lost because the animal spends all its life surrounded by wood. Teredo navalis develops from eggs to metamorphosing larvae in about five weeks. They spend half of this time in
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#17327975082971628-679: 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
1702-443: The Baltic Sea , free-floating piles carved by shipworms can be observed floating hundreds of kilometers away from the original wooden structures. The limiting element for propagation is salinity , which must be greater than 8% for successful reproduction. Reproduction occurs during warm summer months, and the larvae mature for production in just eight weeks. Each year, several generations can be produced. Consequently, freshwater
1776-606: 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 . There were several regional dialects of Ancient Greek; Attic Greek developed into Koine. Ancient Greek
1850-653: The Industrial Revolution and the modern era; as environmental regulation led to cleaner waters, shipworms have returned. Climate change has also changed the range of species; some once found only in warmer and more salty waters like the Caribbean have established habitats in the Mediterranean . Shipworms greatly damage wooden hulls and marine piling , and have been the subject of much study to find methods to avoid their attacks. Copper sheathing
1924-501: 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
1998-520: The Philippines , the shipworm is called tamilok and is eaten as a delicacy. It is prepared as kinilaw —that is, raw (cleaned) but marinated with vinegar or lime juice , chopped chili peppers and onions, a process very similar to shrimp ceviche . Similarly, T. navalis can be found inside the dead and rotten trunk of mangroves in West Papua, Indonesia . To the locals, the Kamoro tribe, it
2072-603: 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 a lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between
2146-406: The family Teredinidae . This species is the type species of the genus Teredo . Like other species in this family, this bivalve is called a shipworm because it resembles a worm in general appearance while at the anterior end it has a small shell with two valves , and it is adept at boring through wood. This species may have originated in the northeast Atlantic Ocean, but has spread around
2220-501: 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)
2294-1031: 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"):
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2368-495: 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
2442-633: 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, Teredo navalis Teredo navalis , commonly called the naval shipworm or turu , is a species of saltwater clam, a marine bivalve mollusc in
2516-545: 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 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
2590-622: The Norse Saga of Erik the Red , Bjarni Herjólfsson , said to be the first European to discover the Americas, had his ship drift into the Irish Sea where it was eaten up by shipworms. He allowed half the crew to escape in a smaller boat covered in seal tar, while he stayed behind to drown with his men. Today shipworms are primarily eaten in parts of Southeast Asia . In Palawan and Aklan in
2664-513: The Teredinidae; she published a detailed monograph on the family, the 1966 volume A Survey and Illustrated Catalogue of the Teredinidae published by the Museum of Comparative Zoology . More recently, the endosymbionts that are found in the gills have been subject to study the bioconversion of cellulose for fuel energy research. Shipworm species comprise several genera , of which Teredo
2738-411: The animals bore their way through the wood or similar medium in which they live and feed. The valves of shipworms are separated and the aperture of the mantle lies between them. The small "foot" (corresponding to the foot of a clam) can protrude through the aperture. When shipworms bore into submerged wood, bacterial symbionts embedded within a sub-organ called the typhlosole in the shipworm gut, aid in
2812-550: 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
2886-419: 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
2960-469: The back of the burrow, which is open to the sea through a narrow aperture. Teredo navalis is a protandrous hermaphrodite . All individuals start their adult life as males, becoming mature when they are a few centimetres long, releasing sperm into the sea. In warmer areas they change into females about eight to ten weeks after settling, but this change may take six months before it occurs in colder climates. The eggs are fertilised when sperm gets sucked into
3034-585: The bottom, the planks will be thereby entirely secured from the effects of the worm." In the Netherlands the shipworm caused a crisis in the 18th century by attacking the timber that faced the sea dike . After that the dikes had to be faced with stones. In 2009, Teredo caused several minor collapses along the Hudson River waterfront in Hoboken, New Jersey , due to damage to underwater pilings. In
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3108-404: The branchial siphon , through which the animal pumps the water that passes over the gills . The two siphons are very long and protrude from the posterior end of the animal. Where they leave the end of the main part of the body, the siphons pass between a pair of calcareous plates called pallets. If the animal is alarmed, it withdraws the siphons and the pallets protectively block the opening of
3182-490: The burrow and protected by a pair of calcareous oar-like pallets. The tunnel is circular in cross section and is lined with calcareous material extruded by the mollusc. It can be up to 60 cm (24 in) long and 1 cm ( 1 ⁄ 2 in) in diameter. They are edible, and are traditionally consumed on the island of Marajó and parts of Thailand . They are commonly described as tasting like clam or oyster, and are often prepared in similar ways. Teredo navalis
3256-713: The burrow of a female through the inhalant siphon . More than a million larvae at a time are brooded in the gill chamber, after which they are released into the sea as veliger larvae. By this time they have developed a velum , a ciliated locomotory and feeding organ , and the rudiments of a straight-hinged shell. They eat phytoplankton and disperse with the current for two to three weeks. During further larval stages they develop siphons and gills. When they are ready to undergo metamorphosis , they search for suitable timber on which to settle. They seem to be able to detect rotting wood and are able to swim towards it when they are close enough. Each one then crawls around until it finds
3330-499: The course of its evolution. The scientists are planning to study the microbes found in the single gill of K. polythalamia to find a new possible antimicrobial substance. Teredo navalis are a cosmopolitan species that can be found both in the Atlantic and Pacific oceans. Since they occupy wooden flotsam and natural driftwood such as dead tree trunks, they are spread as the wood is carried by currents. They also travel inside
3404-615: 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
3478-530: 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 is called 'East Greek'. Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian Greek had come under
3552-485: The digestion of the wood particles ingested, The Alteromonas or Alteromonas -sub-group of bacteria identified as the symbiont species in the typhlosole, are known to digest lignin, and wood material in general. The tough molecular layers of lignin surround the cellulose elementary fibrils in the wood particles, and the lignin must be digested initially to allow access by other enzymes into the cellulose for digestion. Another bacterial species ( Teredinibacter turnerae ), in
3626-510: 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 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
3700-493: The early 19th century, engineer Marc Brunel observed that the shipworm's valves simultaneously enabled it to tunnel through wood and protected it from being crushed by the swelling timber. With that idea, he designed the first tunnelling shield , a modular iron tunnelling framework which enabled workers to tunnel through the unstable riverbed beneath the Thames. The Thames Tunnel was the first successful large tunnel built under
3774-511: The eighteenth century, the Royal Navy resorted to coppering the bottoms of its ships in an attempt to prevent the damage caused by shipworm. No treatment of timber to prevent attack by Teredo navalis has been completely successful. Experiments by the Dutch in the 19th century proved the inefficacy of linseed oil, metallic paint, powdered glass, carbonization (burning the outer layers of
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#17327975082973848-495: The free-living larval stage, by floating timbers carried along by currents, and, historically, from the hulls of wooden vessels. In the Baltic Sea, there were several mass occurrences in the 1930s and 1950s. Food particles, mostly timber raspings but also some microalgae, are extracted from the water passing through the gills where gas exchange also takes place. Waste, reproductive gametes , and larvae are discharged through
3922-405: The gills secrete a variety of cellulose-digesting enzymes which may be secreted into the shipworm gut via a special organ called the gland of Deshayes. These secretions aid the shipworm's own carbohydrate-active enzymes (CAZymes) in digesting the wood particles in combination with the enzymes and potentially other metabolites secreted by the symbiont bacterial in the typhlosole. The excavated burrow
3996-422: The mother's gill chamber before being discharged as free-swimming larvae into the sea. Their sexes alternate, young are hermaphrodites while adults can be either male or female. Typically, organisms are male at first and female subsequently. A second male to female phase may occur, however shipworms rarely live long enough to complete the second phase. They have a lifespan of 1 to 3 years. Shipworm anatomy reveals
4070-508: 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
4144-494: The open sea, and tolerates salinities ranging from five to thirty-five parts per thousand. It is also tolerant of a wide range of temperatures. Individuals have survived temperatures as high as 30 °C (86 °F) and as low as 1 °C (34 °F), though growth and reproduction are restricted to the range from 11 to 25 °C (52 to 77 °F). It can also live without air for about six weeks, using up its stored glycogen reserves. Dispersal to new habitats occurs both during
4218-480: The other hand, with their much bigger shells, can take up to two years to reach harvestable size . 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 ),
4292-487: 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
4366-478: The rest of its life as a tunneller. In their gills, shipworms house Teredinibacter turnerae , a symbiotic bacterium which converts nitrogen (dinitrogen) from the water into a form usable by its host, essential for survival on nitrogen-poor diet of wood. The same bacteria produce cellulase, which allows the host to digest the cellulose in the wood. There is evidence to suggest that Teredinibacter turnerae may also have antibiotic properties. Teredo navalis
4440-408: The scientists, based on the shells they left behind that were the size of baseball bats (length 1.5 metres (4 ft 11 in), diameter 6 cm (2.4 in)). The bivalve is a rare creature that spends its life inside an elephant tusk -like hard shell made of calcium carbonate . It has a protective cap over its head which it reabsorbs to burrow into the mud for food. The case of the shipworm
4514-432: The shipworms, similar to the process of photosynthesis used by green plants to convert the carbon dioxide in the air into simple carbon compounds . Scientists found that K. polythalamia cooperates with different bacteria than other shipworms, which could be the reason why it evolved from consuming rotten wood to living on hydrogen sulfide in the mud. The internal organs of the shipworm have shrunk from lack of use over
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#17327975082974588-517: 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
4662-467: 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 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
4736-544: The tunnel. The pallets are not to be confused with the two valves of the main shell, which are at the anterior end of the animal. Because they are the organs that the animal applies to boring its tunnel, they generally are located at the tunnel's end. They are borne on the slightly thickened, muscular anterior end of the cylindrical body and they are roughly triangular in shape and markedly concave on their interior surfaces. The outer surfaces are convex and in most species are deeply sculpted into sharp grinding surfaces with which
4810-404: The typical organs of a bivalve mollusk, although with dimensional or positional peculiarities due to the thinness and length of the occupied space. Furthermore, some structures find no equivalent in other bivalve groups. Normally, the shipworm's body fills the entire length of the gallery, but the anterior region can retract itself slightly with respect to the latter's extremity. Without the gills,
4884-419: The valves of other bivalve molluscs. They are white, with a covering of pale brown periostracum , and have rough ridges. The mollusc uses them to grasp the wood and slowly enlarges the burrow in which it lives. It has retractable inhalant and exhalant siphons which project through a small hole in the horny septum which blocks the opening of the burrow. When the animal is threatened, the siphons can be drawn inside
4958-407: The viscera only cover one-fourth of the total length and only their anterior part is partially covered by the shell. Shipworms are marine animals in the phylum Mollusca , order Bivalvia , family Teredinidae . They were included in the now obsolete order Eulamellibranchiata , in which many documents still place them. Ruth Turner of Harvard University was the leading 20th century expert on
5032-424: The wood), and any of the usual biocides such as chromated copper arsenate . They also attempted covering wooden pylons with precisely arranged iron nails, but this too had no lasting effect. In 1878, it was discovered that creosote was an effective deterrent, though to work best it had to be applied to soft, resinous woods like pine; in order to work on harder woods such as oak, special care had to be taken to ensure
5106-587: The wooden dike revetments , and to prevent erosion of the dikes and subsequent flooding disasters the revetments had to be replaced with heavy stones, at great expense. The shipworm's arrival in San Francisco Bay around 1920 heralded great destruction to the piers and wharves of harbours. It has spread in the Pacific Ocean where its greater tolerance of low salinity levels has caused damage in areas previously unaffected by native shipworms. In
5180-456: The wooden-hulled vessels that help increase their spread worldwide. However, the origin of T. navalis remains uncertain due to the widespread usage of ships in global trade and the resulting spreading of shipworms. During the free-living larva stage, the species colonizes new habitats and spreads. Larvae are extremely sensitive to the presence of wood and will take advantage of any opportunity to attach to and penetrate wooden structures. In
5254-457: The world. It tunnels into underwater piers and pilings and is a major cause of damage and destruction to submarine timber structures and the hulls of wooden boats. Teredo navalis has an elongated, reddish, wormlike body which is completely enclosed in a tunnel it has made in floating or submerged timber. At the front end of the animal are two triangular, calcareous plates. These are up to 2 cm ( 3 ⁄ 4 in) long and correspond to
5328-480: 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 ,
5402-452: 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 is a literary form of Archaic Greek (derived primarily from Ionic and Aeolic) used in
5476-642: Was used on wooden ships in the latter 18th century and afterwards, as a method of preventing damage by teredo worms. The first historically documented use of copper sheathing was experiments held by the British Royal Navy with HMS Alarm , which was coppered in 1761 and thoroughly inspected after a two-year cruise. In a letter from the Navy Board to the Admiralty dated 31 August 1763 it was written "that so long as copper plates can be kept upon
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