Teredo navalis

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Teredo navalis
Shipworm.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order: Myida
Superfamily: Pholadoidea
Family: Teredinidae
Genus: Teredo
Species:
T. navalis
Binomial name
Teredo navalis
Synonyms
  • Pholas teredo O. F. Müller, 1776
  • Serpula teredo DaCosta, 1778
  • Teredo austini Iredale, 1932
  • Teredo batavus Spengler, 1792
  • Teredo beachi Bartsch, 1921
  • Teredo beaufortana Bartsch, 1922
  • Teredo japonica Clessin, 1893
  • Teredo marina Jeffreys, 1860
  • Teredo morsei Bartsch, 1922
  • Teredo navalis var. occlusa Jeffreys, 1865
  • Teredo novangliae Bartsch, 1922
  • Teredo pocilliformis Roch, 1931
  • Teredo sellii van der Hoeven, 1850
  • Teredo sinensis Roch, 1929
  • Teredo vulgaris Lamarck, 1801

Teredo navalis, commonly called the naval shipworm or turu, [2] is a species of saltwater clam, a marine bivalve mollusc in 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.

Contents

This species may have originated in the northeast Atlantic Ocean, but has spread around 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.

Description

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 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 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. [3] [4] They are edible, and are traditionally consumed on the island of Marajó [2] and parts of Thailand. They are commonly described as tasting like clam or oyster, and are often prepared in similar ways. [5]

Distribution and habitat

Teredo navalis is found in temperate and tropical seas and oceans worldwide. [1] 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. [3] It is found in brackish waters as well as the open sea, and tolerates salinities ranging from five to thirty-five parts per thousand. [4] 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). [4] It can also live without air for about six weeks, using up its stored glycogen reserves. [4] Dispersal to new habitats occurs both during 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. [6]

Biology

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 the back of the burrow, which is open to the sea through a narrow aperture. [7]

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 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 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 the rest of its life as a tunneller. [8]

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. [9] [10] There is evidence to suggest that Teredinibacter turnerae may also have antibiotic properties. [11]

Economic effects

Destruction by Teredo navalis worm in a tree branch Teredo navalis in a branch.JPG
Destruction by Teredo navalis worm in a tree branch

Teredo navalis 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 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. [12] 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. [6]

In the eighteenth century, the Royal Navy resorted to coppering the bottoms of its ships in an attempt to prevent the damage caused by shipworm. [13]

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 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 the wood was completely permeated by the creosote. [14] Submerged wrecks have been protected by wrapping them in geotextiles to provide a physical barrier to the larvae or by reburying them in the sediment. No permanent solution has been found. [6]

Related Research Articles

<span class="mw-page-title-main">Shipworm</span> Family of molluscs

The shipworms, also called Teredo worms or simply Teredo, are marine bivalve molluscs in the family Teredinidae, a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into wood that is immersed in seawater, including such structures as wooden piers, docks, and ships; they drill passages by means of 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).

<span class="mw-page-title-main">Bivalvia</span> Class of molluscs

Bivalvia or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs that have laterally compressed soft bodies enclosed by a calcified exoskeleton consisting of a hinged pair of half-shells known as valves. As a group, bivalves have no head and lack some typical molluscan organs such as the radula and the odontophore. Their gills have evolved into ctenidia, specialised organs for feeding and breathing.

<span class="mw-page-title-main">Siphon (mollusc)</span> Anatomical structure which is part of the body of some aquatic molluscs

A siphon is an anatomical structure which is part of the body of aquatic molluscs in three classes: Gastropoda, Bivalvia and Cephalopoda.

<span class="mw-page-title-main">Ruth Turner</span> American marine biologist

Ruth Dixon Turner was a pioneering U.S. marine biologist and malacologist. She was the world's expert on Teredinidae or shipworms, a taxonomic family of wood-boring bivalve mollusks which severely damage wooden marine installations.

<span class="mw-page-title-main">Myida</span> Order of bivalves

Myida is an order of saltwater and freshwater clams, marine and freshwater bivalve molluscs in the subclass Heterodonta. The order includes such bivalves as soft-shell clams, geoducks and shipworms.

<i>Lyrodus</i> Genus of bivalves

Lyrodus is a genus of ship-worms, marine bivalve molluscs of the family Teredinidae.

<span class="mw-page-title-main">Pseudofeces</span> Mucus bound masses with indigestable material suspended in it created by bivalves

Pseudofeces or pseudofaeces are a specialized method of expulsion that filter-feeding bivalve mollusks use in order to get rid of suspended particles such as particles of grit which cannot be used as food, and which have been rejected by the animal. The rejected particles are wrapped in mucus, and are then expelled without having passed through the digestive tract. Thus, although they may closely resemble the mollusk's real feces, they are not actually feces, hence the name pseudofeces, meaning false feces.

<i>Mya truncata</i> Species of bivalve

Mya truncata, common name the blunt gaper or truncate softshell, is a species of edible saltwater clam, a marine bivalve mollusk in the family Myidae.

John L. Culliney is an American biologist, a retired professor of biology and marine biology at Hawaii Pacific University.

Teredo portoricensis, known commonly as the Puerto Rico shipworm, is a species of wood-boring clam or shipworm, a marine bivalve mollusk in the family Teredinidae.

Solemya velum, the Atlantic awning clam, is a species of marine bivalve mollusc in the family Solemyidae, the awning clams. This species is found along the eastern coast of North America, from Nova Scotia to Florida and inhabits subtidal sediments with high organic matter (OM) content and low Oxygen, such as salt ponds, salt marshes, and sewage outfalls.

<i>Ensis ensis</i> Species of bivalve

Ensis ensis, or the sword razor, is a razor clam, a marine bivalve mollusc in the family Pharidae. It lives buried in the sand and is found off the coasts of northwest Europe.

<i>Fabulina fabula</i> Species of bivalve

Fabulina fabula, the bean-like tellin, is a species of marine bivalve mollusc in the family Tellinidae. It is found off the coasts of northwest Europe, where it lives buried in sandy sediments.

Kuphus is a genus of shipworms, marine bivalve molluscs in the family Teredinidae. While there are four extinct species in the genus, the only extant species is Kuphus polythalamius. It is the longest bivalve mollusc in the world, where the only known permanent natural habitat is Kalamansig, Sultan Kudarat in the Philippines.

<i>Teredo</i> (bivalve) Genus of molluscs

Teredo is a genus of highly modified saltwater clams which bore in wood and live within the tunnels they create. They are commonly known as "shipworms;" however, they are not worms, but marine bivalve molluscs in the taxonomic family Teredinidae. The type species is Teredo navalis.

Laternula elliptica is a species of saltwater clam, a marine bivalve mollusc in the family Laternulidae, the lantern shells. It is the largest bivalve found under the surface of the seabed in the Southern Ocean.

Teredora princesae is a species of marine bivalve mollusc in the family Teredinidae, the shipworms. This species lives in timber that is floating in the western Pacific Ocean.

Potamocorbula amurensis is a species of small saltwater clam, a marine bivalve mollusc in the order Myida. Common names include the overbite clam, the Asian clam, the Amur River clam and the brackish-water corbula. The species is native to marine and brackish waters in the northern Pacific Ocean, its range extending from Siberia to China, Korea and Japan. It has become naturalised in San Francisco Bay.

<i>Psiloteredo megotara</i> Species of clam

Psiloteredo megotara is a species of saltwater clam, a marine bivalve mollusc in the family Teredinidae, the shipworms.

Kuphus polythalamius is a species of shipworm, a marine bivalve mollusc in the family Teredinidae.

References

  1. 1 2 Rosenberg, Gary (2010). "Teredo navalis Linnaeus, 1758". WoRMS. World Register of Marine Species . Retrieved 2012-04-13.
  2. 1 2 Siqueira, Andréa D.; Murrieta, Rui S. S.; Brondizio, Eduardo (2000). Land Tenure, Access to Resources, and Food Security in the Amazon Estuary. Constituting the Commons: Crafting Sustainable Commons in the New Millennium, the Eighth Biennial Conference of the International Association for the Study of Common Property. hdl:10535/2003.
  3. 1 2 Palomares ML, Pauly D, eds. (2011). "Teredo navalis" in SeaLifeBase. April 2011 version.
  4. 1 2 3 4 "Teredo navalis". Indian River Lagoon Species Inventory.
  5. ↑ Wiens, Mark (2014-11-27). "Teredo Navalis - Look Like Worms, Taste Like Clams (แกงเลียงเพรียง)". Migrationology - Food Travel Blog.
  6. 1 2 3 "Teredo navalis" (PDF). NOBANIS – Invasive Alien Species Fact Sheet. Retrieved 2012-04-13.
  7. ↑ Shipworm at the Encyclopædia Britannica
  8. ↑ "Teredo Vermehrung" [Shipworm lifecycle]. Küstenbiologie (in German).
  9. ↑ "Teredo Worm". Poseidon Sciences. June 7, 2023. Retrieved April 17, 2023.
  10. ↑ Distel, Daniel L; Morrill, Wendy; MacLaren-Toussaint, Noelle; Franks, Dianna; Waterbury, John (November 2002). "Teredinibacter turnerae gen. nov., sp. nov., a dinitrogen-fixing, cellulolytic, endosymbiotic gamma-proteobacterium isolated from the gills of wood-boring molluscs (Bivalvia: Teredinidae)". International Journal of Systematic and Evolutionary Microbiology. 52 (pt6) (Pt 6): 2261–2269. doi:10.1099/00207713-52-6-2261. PMID   12508896 – via Pubmed.
  11. ↑ Trindade-Silva, Amaro E; Machado-Ferreira, Erik; Senra, Marcus V.X.; Vizzoni, Vinicius F; Yparraguirre, Luciana A.; Leoncini, Orilio; Soares, Carlos A.G. (March 23, 2009). "Physiological traits of the symbiotic bacterium Teredinibacter turnerae isolated from the mangrove shipworm Neoteredo reynei". Genetics and Molecular Biology. 32 (3): 572–581. doi:10.1590/S1415-47572009005000061. PMC   3036054 . PMID   21637522 – via SciElo Brazil.
  12. ↑ Sundberg, Adam (2015-08-16). "Molluscan Explosion: The Dutch Shipworm Epidemic of the 1730s". Arcadia. ISSN   2199-3408.
  13. ↑ Harris, J. R. (1966). "Copper and Shipping in the Eighteenth Century". The Economic History Review. 19 (3): 550–568. doi:10.2307/2593163. ISSN   0013-0117. JSTOR   2593163.
  14. ↑ Eduard Hendrik van Baumhauer (1878). The Teredo Navalis, and the Means of Preserving Wood from Its Ravages. p. 19.
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