TEREDO NAVALIS

Teredo navalis, the naval shipworm, is a species of saltwater clam, a marine bivalve mollusc in the family Teredinidae, the shipworms. 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 of two valves which is specialised to bore through wood.

Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Bivalvia
Order:	Myoida
Family:	Teredinidae
Genus:	Teredo
Species:	T. navalis
Binomial name
Teredo navalis Linnaeus, 1758

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 (0.8 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 rasp 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 (0.4 in) in diameter.

Distribution and Habitat

Teredo navalis is found in temperate and tropical seas and oceans worldwide. It may have originated in the northeast Atlantic Ocean, but it is difficult now to establish from where it originally came because it has spread so efficiently around the world. It is found in the littoral zone,  living inside submerged timber, pilings, driftwood, and the hulls of wooden boats. It is found in brackish waters as well as 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 °C (52 °F) to 25 °C (77 °F). It's can also live without air for about 6 weeks, using up its stored glycogen reserves. 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. However, the low salinity in the northern Baltic Sea keeps the shipworm out. Thus, shipwrecks in the northern Baltic can be preserved for long periods of time.

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. The gills also contain symbiotic nitrogen-fixing bacteria, which produce enzymes that help to digest the cellulose in the wood. Waste, reproductive gametes, and larvae are discharged through 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 8 to 10 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 2 to 3 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.

Economic Effects

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 centimetres (12 in) in diameter being completely warped 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 dykes 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.

Destruction by Teredo worm in a tree branch.

In the eighteenth century the British Royal Navy resorted to covering the bottoms of its ships with copper in an attempt to prevent the damage caused by shipworm, giving rise to the expression "copper-bottomed".

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 (i.e., 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. 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. The only permanent solution to attack by Teredo navalis, however, is to replace wood in submerged constructions with some other material.

References

1. ^b Rosenberg, Gary (2010). "Teredo navalis Linnaeus, 1758". World Register of Marine Species. Retrieved 2012-04-13.
2. ^ ^a b c Teredo navalis Linnaeus, 1758 – Naval shipworm. SeaLifeBase. Retrieved 2012-04-13.
3. ^ ^a b c d Teredo navalis – Naval Shipworm. Smithsonian Marine Station at Fort Pierce. Retrieved 2012-04-13.
4. ^ ^a b c Teredo navalis. NOBANIS – Invasive Alien Species Fact Sheet. Retrieved 2012-04-13.
5. ^ Shipworm. Encyclopædia Britannica Online. Retrieved 2012-04-13.
6. ^ Shipworm lifecycle. Küstenbiologie Kai Hoppe. Retrieved 2012-04-13.
7. ^ Sundberg, Adam (2015). "Molluscan Explosion: The Dutch Shipworm Epidemic of the 1730s". Arcadia (Rachel Carson Center for Environment and Society) 14. ISSN 2199-3408 
8. ^ Harris, J. R. (1966). "Copper and shipping in the eighteenth century, (PDF). The Economic History Review 19 (3): 550–68. doi:10.1111/j.1468-0289.1966.tb00988.x.
9. ^ Eduard Hendrik van Baumhauer (1878). The Teredo Navalis, and the Means of Preserving Wood from Its Ravages.

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Xylophagy

Xylophagy is a term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily (often solely) of wood. The word derives from Greek ξυλοφάγος (xulophagos) "eating wood", from ξύλον (xulon) "wood" and φαγεῖν (phagein) "to eat", an ancient Greek name for a kind of a worm-eating bird. Animals feeding only on dead wood are called sapro-xylophagous or saproxylic.

Worker termite

Xylophagous Insects

Most such animals are arthropods primarily insects of various kinds, in which the behavior is quite common, and found in many different orders. It is not uncommon for insects to specialize to various degrees; in some cases, they limit themselves to certain plant groups (a taxonomic specialization), and in others, it is the physical characteristics of the wood itself (e.g., state of decay, hardness, whether the wood is alive or dead, or the choice of heartwood versus sapwood versus bark).

Many xylophagous insects have symbiotic protozoa and/or bacteria in their digestive system which assist in the breakdown of cellulose; others (e.g., the termite family Termitidae) possess their own cellulase. Others, especially among the groups feeding on decaying wood, apparently derive much of their nutrition from the digestion of various fungi that are growing amidst the wood fibers. Such insects often carry the spores of the fungi in special structures on their bodies (called "mycangia"), and infect the host tree themselves when they are laying their eggs.

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XYLOTHEQUE

A xylotheque (from the Greek xylon for "wood" and "theque" meaning "repository") is a wood collection.

A xylotheque is something more than just collection of wood just as a library is more than merely a collection of books. Almost all rather developed countries with worries about their flora have at least one xylotheque with their flora and one with flora from other places in the world.

The xylotheque with a largest number of samples is the Samuel James Record Collection formerly housed at the Forestry School of Yale University in New Haven, Connecticut and was transferred to the U.S. Forest Service, Forest Products Laboratory in 1969, which houses 60,000 samples. The second largest xylotheque belongs to the Royal Museum of Central Africa in Tervuren Belgium. As of September 2004, it had 57,165 samples. The Thünen Institute of Wood Research in Hamburg has more than 37,000 samples.

Interior of the Xiloteque Manuel Soler, in Dénia (Spain)

Other important xylotheques are:

Xyloteque	Samples
Bogor (Indonesia)	32,000
RBG Kew ((UK)	20,000
Chicago (USA)	18,000
Melbourne (Australia)	17,000
Dehra Dun (India)	15,000
Laguna (Philippines)	11,000
Saint Petersburg (Russia)	8,000
Kepong (Malaysia)	7,000
Mexico	6,000
Costa Rica	6,000

A xylotheque is useful to understand the scientific and economic value of the existing woods. At the same time, their samples are used to study the xylotomy, physical and mechanical wood properties, such as durability and preservation. The existence of xylotheques has also immediate applications for anyone who needs to make a morphological-visual analysis of wood. These include technicians, specialists and woodworkers, and also those involved in industry and commerce.

Even a modest wood collection has value, as each of its samples is a compendium or monography that encloses a vast information. They are very important in museums, schools and universities for didactic and docent value. For example, there is a ludic xylotheque in the Arboretum de Pézanin, with more of 200 samples, whose weight the visitor is able to compare.

A xylotheque becomes really interesting and its use is essential as a study tool and a reference to investigations about identification, use and substitution of woods in real state and movable of our cultural patrimony, as well as in preservation and restoration.

Notes

1.  "Forest Products Laboratory - USDA Forest Service. www.fpl.fs.fed.us. Retrieved 2015-09-21.
2. ^ "Woods of the World in the Thünen Institute. Johann Heinrich von Thünen Institute. Retrieved 2013-10-09.

External Links

• International Wood Collectors Society
• Xiloteca Manuel Soler (One of the largest private collection of wood samples)
• Wood Collection Xiloteca Imanol Artola (Zumárraga, España)
• Wood Collection

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XYLOTOMY

Xylotomy is the preparation of small slivers of wood for examination under a microscope often using a microtome.

A microscopic section of wood

It is useful for providing forensic evidence in some criminal cases where finding a fragment of wood on an individual and matching it to a weapon used in a crime would be helpful. One xylotomist, Arthur Koehler, was able to provide crucial evidence by linking a piece of pine from a ladder used in a kidnapping to one particular factory whose machinery was defective, and from there to one particular lumberyard. Koehler searched for eighteen months for the yard, and presented his evidence dramatically in court by presenting the court with a chalk rubbing of the samples, which he made there and then, demonstrating that they were identical. He also matched other pieces of the ladder to a chisel used to create the joists, missing from the defendant's tool chest, and to a missing plank from the suspect's attic floor.

A microtome, used in the process of xylotomy

It may also be useful in forestry studies. Identifying the species of a piece of wood is not always easy, in which case a xylotheque may provide samples with which the xylotomist can compare his own. Xylotomy may be carried out by a forensic biologist. People who specialize in xylotomy are difficult to obtain. The public have been known to confuse it with someone who plays the xylophone and they do not tend to take much interest in the subject.

References

1. World of Forensic Science article
2.  Illinois Digital Newspaper Collection
3. ^Nightmare remembered
4. ^ New Jersey v. Hauptmann (Cont'd)
5. ^ THE XYLOTOMIST, Post-Standard, The Thursday, September 22, 1910
6. ^ Washington Post, The Wednesday, August 24, 1910

- Wikipedia 

DRIFTWOOD

Driftwood is wood that has been washed onto a shore or beach of a sea, lake, or river by the action of winds, tides or waves. It is a form of marine debris or tidewrack.

In some waterfront areas, driftwood is a major nuisance. However, the driftwood provides shelter and food for birds, fish and other aquatic species as it floats in the ocean. Gribbles, shipworms and bacteria decompose the wood and gradually turn it into nutrients that are reintroduced to the food web. Sometimes, the partially decomposed wood washes ashore, where it also shelters birds, plants, and other species. Driftwood can become the foundation for sand dunes.

A beach covered with driftwood

Most driftwood is the remains of trees, in whole or part, that have been washed into the ocean, due to flooding, high winds, or other natural occurrences, or as the result of logging. There is also a subset of driftwood known as drift lumber. Drift lumber includes the remains of man-made wooden objects, such as, buildings and their contents washed into the sea during storms, wooden objects discarded into the water from shore, dropped dunnage or lost cargo from ships (jetsam), and the remains of shipwrecked wooden ships and boats (flotsam). Erosion and wave action may make it difficult or impossible to determine the origin of a particular piece of driftwood.

Driftwood provides a perch for a bald eagle on Fir Island (Washington).

Driftwood can be used as part of decorative furniture or other art forms, and is a popular element in the scenery of fish tanks.

Fire

The EPA includes driftwood in its list of "Items You Should Never Burn in Your [Wood-Burning] Appliance," because it will "release toxic chemicals when burned".

Driftwood in History

According to Norse mythology, the first humans, Ask and Embla, were formed out of two pieces of driftwood, an ash and an elm, by the god Odin and his brothers, Vili and Vé.

The Vikings would cast wood into the sea before making landfall. And the location of the wood would be an indication as to where to build their mead halls. The wood used would found the high-seat pillars of the new hall.

Driftwood carried by Arctic rivers was the main, or sometimes only, source of wood for some Inuit and other Arctic populations living north of the tree line until they came into regular contact with European traders. Traditional Inuit boats such as the kayak were fashioned from driftwood frames covered in skins. Wood that is burned today in these regions mainly consists of the remains of condemned wooden structures. Driftwood is still used as kindling by some.

The "Old Man of the Lake", in Crater Lake, Oregon is a full-size tree that has been bobbing vertically in the lake for more than a century. Due to the cold water of the lake, the tree has been well preserved.

These large diameter Sequoia sempervirens, logs spent enough time exposed to wave action to round their contours before being driven into the mouth of a narrow ravine by storm surf. Sequoia's high tannin content is resistant to decay, so these logs retain structural strength for decades. Storm flows within Shorttail Gulch are insufficient to move the logs back to sea. This unique habitat at the mouths of small estuaries of the California coast is threatened by the diminished quantity of large redwood logs available in flood waters since the logging of aboriginal forests.

Alice Gray, the legendary "Diana of the Dunes", who fought to preserve the Indiana Dunes which contain quantities of driftwood named her college "Driftwood", and made all her furniture from driftwood.

Driftwood Sculptures

Driftwood Sculptures are sculptures that are made of driftwood on beaches or mudflats :

Driftwood sculpture of a horse by artist Heather Jansch at the Eden Project.

• At Kullaberg, Sweden, Lars Vilks created Nimis a driftwood artwork in the year 1980. This sculpture and two others led to the declaration of Ladonia as an independent nation.
• Sculptures were created on the Emeryville, California mudflat and marsh area of San Francisco Bay, in the late 1960s.
• A driftwood sculpture was constructed in the Chapelle St Anne. d' Arles (France) by the visitors to the exhibition "Marcher dans le pas des glaneurs" organized by "A Flots perdus" (Arlésiens artists), in March 2008.
• The Ashden Awards for Sustainable Energy (sometimes called the "Green Oscars") are sculpted out of driftwood.
• Artist Deborah Butterfield is known for her sculptures of horses, initially rendered from driftwood before being cast in bronze.
• Artist Melanie Klaas is well known for her driftwood big game fish sculptures such as marlin and tuna as seen in Marlin

Driftwood sculpture of a locomotive in or near Emeryville, California, at the edge of the San Francisco Bay, 1977.

References

1. ^ http://www.epa.gov/burnwise/bestburn.html.
2. ^ pantheons and gods website. God checker.com Retrieved 09/09/2011
3. ^ [1]Heathen Practices in the Viking Age
4. ^ Salinas, J., "The Old Man of the Lake," Nature Notes from Crater Lake National Park, Vol. XXVII (1996).
5. ^ Smith, S. & Mark, S. (2009). The Historical Roots of the Nature Conservancy in the Northwest Indiana/Chicagoland Region: From Science to Preservation. The South Shore Journal, 3. http://www.southshorejournal.org/index.php/issues/volume-3-2009/83-journals/vol-3-2009/75-the-historical-roots-of-the-nature-conservancy-in-the-northwest-indianachicagoland-region-from-science-to-preservation
6. ^ Smith, S. & Mark, S. (2006). Alice Gray, Dorothy Buell, and Naomi Svihla: Preservationists of Ogden Dunes. The South Shore Journal, 1. http://www.southshorejournal.org/index.php/issues/volume-1-2006/78-journals/vol-1-2006/117-alice-gray-dorothy-buell-and-naomi-svihla-preservationists-of-ogden-dunes.
7. ^ Heather Jansch - Sculptor - Driftwood - Bronze.
8. ^ Deborah Butterfield on artnet.

- Wikipedia