Shipworm

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Shipworm
This dried specimen of Teredo navalis, and the calcareous tunnel that originally surrounded it and curled into a circle during preservation, were extracted from the wood of a ship. The two valves of the shell are the white structures at the anterior end; they are used to dig the tunnel in the wood.
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Superorder: Imparidentia
Order: Myida
Superfamily: Pholadoidea
Family: Teredinidae
Rafinesque, 1815
Genera

See text

The shipworms, also called Teredo worms or simply Teredo (from

magnum opus, Systema Naturæ
(1758).

Characteristics

Popular Science Monthly
, September 1878

Removed from its burrow, the fully grown teredo ranges from several centimeters to about 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.

bivalves. The ctinidia lie mainly within 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 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 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, bacteria (

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.[4]

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.[5]

Anatomy

Disposition of the main organs in a shipworm. GDA: anterior digestive gland; GDV: ventral digestive gland, with its orifices in the stomach. Orifices uri. et gen., urinary and gential orifices. The left ventricle is sectioned near its base. The nerve ganglion is in blue. The distance between pallets and foot spans several time the animal's diameter.

Shipworm anatomy reveals 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.

  1. Gills are divided in two halves, the anterior one of small size, the posterior one much more developed. They are linked by the alimentary tract running on the side of the visceral mass.
  2. The heart-kidney system is tilted, bringing the kidneys in a dorsal position relative to the heart, whose atria find themselves behind the ventricle. Furthermore, the anterior and posterior aorta become respectively posterior and anterior.
  3. The anus opens at the end of a long anal tube.
  4. The digestive gland is divided into several parts, with separate orifices in the stomach.
  5. A vast
    caecum
    is linked to the stomach.
  6. The digestive tube bears a very peculiar structure, the gland of Deshayes, probably homologous to salivary glands,[6] which link to the oesophagus and stretch to the dorsal side of the posterior part of the gills.
  7. The orifice of the gallery bears pallets with their own musculature.
  8. The siphon retractor muscles are inserted on the calcareous covering of the gallery, and not on the shell's valves which are much further out.
  9. The anterior and posterior anterior muscles have an antagonistic action.

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, the viscera only cover one-fourth of the total length and only their anterior part is partially covered by the shell.[7][8]

Taxonomy

Shipworms are marine animals in the phylum Mollusca, order Bivalvia, family Teredinidae. They were included in the now obsolete order Eulamellibranchiata,[9] in which many documents still place them.

Ruth Turner of Harvard University was the leading 20th century expert on 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.[10]

Shipworm species comprise several genera, of which Teredo 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:[11]

Species

The

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 the course of its evolution[citation needed] The scientists are planning to study the microbes found in the single gill of K. polythalamia to find a new possible antimicrobial substance[citation needed
]

Habitat

global trade and the resulting spreading of shipworms.[16]

During the free-living

invertebrates.[4] Their ideal temperature range is 15 to 25 degree C and therefore T. navalis can be found in temperate and tropical zones.[16]

The shipworm lives in waters with

brackish Baltic Sea, where wooden shipwrecks are preserved for much longer than in the oceans.[17]

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 the Industrial Revolution and the modern era; as environmental regulation led to cleaner waters, shipworms have returned.[18] 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.[18]

Cultural impact

Shipworms greatly damage wooden hulls and marine

piling, and have been the subject of much study to find methods to avoid their attacks.[18] Copper sheathing 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 the bottom, the planks will be thereby entirely secured from the effects of the worm."

In the

sea dikes. After that the dikes had to be faced with stones. In 2009, Teredo have caused several minor collapses along the Hudson River waterfront in Hoboken, New Jersey, due to damage to underwater pilings.[19]

Teredolites borings in a modern wharf piling. The US one cent coin in the lower left of this image is 19 mm across.

In 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 a navigable river.[18][20]

Moby Dick, had been weakened by shipworms.[18] In the Norse Saga of Erik the Red, Bjarni Herjólfsson, said to be the first European to discover the Americas,[22]
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.

Cuisine

Shipworm as tamilok

Today shipworms are primarily eaten in parts 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.

oysters, on the other hand, with their much bigger shells, can take up to two years to reach harvestable size.[24]

See also

References

  1. ^ Garcia, Sierra (2021-12-24). "How "Termites of the Sea" Have Shaped Maritime Technology". JSTOR Daily. Retrieved 2022-05-01.
  2. ^ Castagna, Michael. "Shipworms and Other Marine Borers" (PDF). National Oceanic and Atmospheric Administration. United States Department of the Interior Fish and Wildlife Service Bureau of Commercial Fisheries. Retrieved 30 November 2023.
  3. ISSN 1466-5026. Archived from the original on 2008-09-07. Retrieved 2010-09-23.{{cite journal}}: CS1 maint: DOI inactive as of April 2024 (link
    )
  4. ^ a b c Didžiulis, Viktoras. "Invasive Alien Species Fact Sheet – Teredo navalis" (PDF). Nobanis. Retrieved 30 November 2023.
  5. ^ "Teredo navalis". Marine Invasions Research at the Smithsonian Environmental Research Center. Retrieved 30 November 2023.
  6. ^ Morton, B. (1978). "Feeding and digestion in shipworms". Oceanography and Marine Biology – an Annual Review (16): 107–144.
  7. ^ Sigerfoos, C. P. (1907). "Natural history, organization, and late development of the Teredindæ, or ship-worms". Bulletin of the Bureau of Fisheries. 27: 191–231. Bureau of Fisheries Document No. 639.
  8. ^ Turner, Ruth (1966). A survey and illustrated catalogue of the Teredinae (Mollusca: Bivalvia). Cambridge, Massachusetts: The Museum of Comparative Zoology, Harvard University. pp. 8–45.
  9. ISBN 978-0-520-25092-5
    .
  10. PMID 19568419
    .
  11. ^ Bouchet, P. (2015). "Teredinidae Rafinesque, 1815". WoRMS. World Register of Marine Species. Retrieved 2015-02-14.
  12. ^ Didžiulis, Viktoras. "NOBANIS - Invasive Alien Species Fact Sheet - Teredo navalis" (PDF). Retrieved 30 November 2023.
  13. ^ "This Is a Giant Shipworm. You May Wish It Had Stayed In Its Tube. - T…". The New York Times. 2020-11-15. Archived from the original on 2020-11-15.
  14. ^ [1] Live example seen on 19 April 2017 on the BBC's website.
  15. ^ Castagna, Michael. "Shipworms and Other Marine Borers" (PDF). National Oceanic and Atmospheric Administration. United States Department of the Interior Fish and Wildlife Service Bureau of Commercial Fisheries. Retrieved 30 November 2023.
  16. ^ a b Ho, Maggie. "Teredo navalis". Marine Invasions Research at the Smithsonian Environmental Research Center. Retrieved 30 November 2023.
  17. ^ "Historic shipwrecks could be preserved in the Antarctic". ScienceNordic. Archived from the original on 2017-02-28. Retrieved 2017-02-28.
  18. ^ a b c d e Gilman, Sarah (December 5, 2016). "How a Ship-Sinking Clam Conquered the Ocean". Smithsonian.
  19. ^ "Pier-eating monsters: Termites of the sea causing piers to collapse". Hudson Reporter. Retrieved 2009-09-29.
  20. ^ "Thames Tunnel Construction". Brunel Museum. Archived from the original on 2008-06-14. Retrieved 2008-08-31.
  21. ^ Thoreau, Henry D., "Though All the Fates".
  22. ^ "The Saga of Erik the Red". Icelandic Saga Database. Retrieved 2017-07-04.
  23. ^ "Renaissance of Kamoro Culture | Stichting Papua Erfgoed". www.papuaerfgoed.org.
  24. ^ a b coxworth, Ben (20 November 2023). "Wood-eating shipworms may soon be farmed for shipworm-eating humans". New Atlas. Retrieved 30 November 2023.
  25. ^ Ortiz, Jodelen O. (May 2, 2007). "Tamilok A Palawan: Delicacy". Archived from the original on April 17, 2009. Retrieved 2009-04-30.

Further reading

External links

Look up shipworm in Wiktionary, the free dictionary.
  • Texts on Wikisource:
    • "
      New International Encyclopedia
      . 1905.
    • Baumhauer, Eduard Hendrik von (September 1878). "
      Popular Science Monthly
      . Vol. 13.
    • Baumhauer, Eduard Hendrik von (August 1878). "
      Popular Science Monthly
      . Vol. 13.
    • "
      Popular Science Monthly
      . Vol. 3. May 1873.
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