Waterfront: A Walk Around Manhattan (21 page)

The first literary mention of the creature I have been able to find appears in a comedy by Aristophanes,
The Knights
, where the playwright imagines a dialogue between several ships, the eldest trireme saying that, rather than be sent on a dangerous expedition, she would prefer to remain at home, grow old, and be eaten by shipworms. Ovid, in a line almost too famous to quote, speaks of his heart constantly nibbled by sorrow, “gnawed as a ship is injured by the hidden borer”
(estur ut occulta vitiata teredine navis).
Theophrastus describes the creature scrupulously, though Pliny mixes fact and fancy in his
Natural History
, mistakenly saying that “borerworms have a very large head in relation to their size,” and confusing them with the grub of an insect. In the Middle Ages, the scholar-monk Yscolan wrote: “A full year I was placed / At Bangor, on the pole of a weir. / Consider thou my sufferings from sea-worms.” Curiously, we find no mention of shipworms in Homer, Dante, Shakespeare, Rabelais, Goethe,
Pushkin, and other authors of universal genius. But it crops up frequently in accounts of the Age of Exploration, being blamed for the failure of Columbus's fourth voyage in 1502, when all his vessels had to be shelved because of problems with their bottoms. Sir Francis Drake's flagship was found riddled with shipworms when it returned from circumnavigating the globe. The “Zee-worm” devastated Holland in the 1730s. As Smollett reports, “The Dutch were greatly alarmed by an apprehension of being overwhelmed by an inundation occasioned by worms, which were said to have consumed the piles of timber work that supported their dykes. They prayed and fasted with uncommon zeal in terror of this calamity, which they did not know how to avert in any other manner. At length they were delivered from their fears by a hard frost, which effectually destroyed these dangerous animals.”

Perhaps because Holland suffered so much shipworm damage, Dutch scientists led the way in investigating the malicious mollusk. Godfrey Sellius's 366-page Latin treatise,
Historia Naturalis Teredinis seu Xylophagi marini
(1733), is still regarded as a masterpiece of research. The British scientist J. B. Jeffreys observed about Sellius in his own nicely written
British Conchology
(1865): “The subject appears to have fascinated him, much in the same way as a capricious mistress does her lover, who now deprecates the cruelty of his fair tormentor, and then extols to the skies her beauty and gentleness. He calls the
Teredo
a wicked beast, the worst plague that angry Nature could inflict on man; but he defends it against the calumnies of certain anonymous writers who had preceded him, and he expresses in enthusiastic terms his admiration of its symmetry, economy, ingenuity, social harmony … and its wonderful perfection in every particular.” Clearly the shipworm has the power to dazzle susceptible mentalities. Jeffreys himself fell under its spell, exclaiming, “I do not know any conchological study more interesting and important, and at the same time more difficult, than that of the
Teredo.
”

Let us take a closer look at its anatomy. The clamlike creature has a bivalve shell that functions as a tool, the rough, ridged valve surfaces being used for boring and scraping. These ridges or “dentricles” are what Pliny mistook for teeth. It also has a muscular foot that permits crawling over surfaces and acts as a suction cup, holding the shell in place during burrowing. The creature's breathing siphons remain at the surface of the
wood, taking in water and oxygen. Once attached to a piece of wood, the larva starts to turn into a proper shipworm—a metamorphosis, Jeffreys assures us, that is “not less wonderful than that which takes place in the frog, insect, or polyp.” The adult form has a soft, almost gelatinous body and deposits a whitish, calcareous lining on its tunnel walls to protect its gentle flesh.

The shipworm requires three main conditions for life: proper temperature, salinity, and the presence of wood. A habitué of the sea, it does not fare well in freshwater lakes or inlets. It requires salinities ranging from normal sea water—averaging about 35 parts per thousand—to as low as 9 parts per thousand, according to Dr. Ruth Turner, the Harvard marine biologist who recently passed away at eighty-five, after devoting her life to studying the teredo. (Her obituary says she was affectionately called “Lady Wormwood,” she scuba-dived until she was well into her seventies, and she never married, giving her heart, perhaps, to the shipworm.) Sellius, who experimented by thrusting shipworms into beer, rainwater, and milk, discovered, as one might predict, that they did not prosper. They dislike cold, breed in warm weather, and, when placed in a jar, invariably seek the sunny side. They also prefer shallow water, and are found most often around or slightly above the mud line. Though originally associated with one or another region, as a sort of local curse, they can be dispersed considerable distances by ocean currents, and may wash up anywhere on the globe, provided they have secured adequate ligneous transportation.

Their palates, well described by Sigerfoos (1908), are peculiar, tubelike structures that extrude siphons, which take in food and considerable amounts of water, which in turn help reduce the wood to a flocculent mass. These palates look like pieces of appendix, or asparagus stalks, or bent penises, hence the misnomer “worm.” They soon outgrow the shell, which in any case is too frail to possess much protective function. If the shell is thin compared to that of other bivalves, it is perhaps because the shipworm finds all the protection it needs by lodging in a piece of wood. Once it has gained its hiding place, it escapes assault from other predators. Should another shipworm enter the abode, the first will make way. A single two-by-four may house three dozen teredos, recumbently sharing the space as in a crack den.

Sellius championed his creature's nondisputatious nature, Jeffreys tells us, arguing that the shipworm, while not of a sociable habit, “is actuated by a conscientious anxiety not to infringe on its neighbor. When a collision is imminent, it secretes a cup-shaped dome or plug in front, of a thinner texture than the rest of its sheath; and it shuts itself up. Sometimes it makes several of these outer walls, one after another. It then, being unable to eat its way through the wood and thus procure a supply of food, dies of starvation, preferring suicide to the alternative of invading and injuring its companions!” Sellius ascribed a fine sense of honor to his “hero,” as he called the teredo. Whether the shipworm disdains to engage in territorial disputes out of chivalry or morose self-absorption remains an open question. That it is not always so pacific may be seen by the testimony of a later observer, Clapp (1951), who recorded the actions of one shipworm species, not sure whether he was witnessing fighting or copulation:

This probing and tearing activity of the excurrent siphon is quite violent. The siphon arches and waves wildly in all directions with gyrations which might be likened to those of the trunk of a very active miniature elephant…. In spite of the struggles of the incurrent siphon, the excurrentsiphon generally eventually succeeds in pushing the tip end for a considerable distance down the inside of the incurrent siphon and is able to maintain a firm attachment there. After a few seconds, active resistance by the incurrent siphon ceases, and the excurrent siphon may then remain in this position for several minutes. During this period, a minute amount of a somewhat transparent fluid may clearly be seen though the transparent walls of both siphons, being ejected spasmodically from the excurrent siphon into the incurrent siphon.

This sounds like sex to me. Unfortunately, we have no way of knowing if there was any sperm transfer, because Clapp did not collect the transparent fluid. Those who are interested in such matters may consult another paper, “Sexual rhythm in the pelecypod mollusk Teredo,” by Wesley Roswell Coe.

As Sigerfoos first postulated, the shipworm's sexuality is protandrous, which means it is hermaphroditic, metamorphosing from a male to a female in the course of its development. In shipworms, the female is
always more mature than the male. Propagation may occur in three ways: (1) both sperm and eggs are released into the water by the individual in vast numbers (100 million eggs in one spawning), and the pairings allowed to occur as they may; (2) the sperm may be extruded into the water and then stored in the gills of the individual, where fertilization subsequently takes place; or (3) an excurrent siphon of a male may eject semen directly into the incurrent siphon of a female, as vividly described by the eminent Clapp, above.

Within hours after the eggs are laid, the embryos become free-swimming. The larvae will navigate around, searching opportunistically for some minuscule opening in a piece of wood: “the hull of a vessel or boat, a harbour-pile, a shipping-stage, a floating tree or the roots of one growing on the banks of an estuarine river, a piece of bark timber, a fish-erman's cork, a cocoa-nut, a bamboo rod, a walking-stick, a beacon or buoy, a mast, rudder, oar, plank, cask, hencoop, or other ligneous waif or stray of the ocean” ( Jeffreys). The fry have a few hours, or at most a few days, in which to infiltrate their host medium. Once successfully inside, however, they can snuggle in and begin their burrow. Scraping diligently in a path that follows along the grain of the wood, they grow very rapidly, outstripping their shells and acquiring their look of waving asparagus. When they meet a knot in the grain, they often curve around it, though some will burrow straight through. They will literally eat themselves out of house and home. But a lucky shipworm, encountering sufficient food supply and no impediments, can grow indefinitely, attaining a size of two feet or more. Dr. Ruth Turner found one in the tropics that was three feet long, which borders on sea-monster dimensions.

Once a shipworm claims a home, it is stuck there for the rest of its life. Efforts to transplant healthy, intact specimens from one plank to another have all resulted in fatality. They are loyal to their habitat; give them that. You may think of the shipworm inching forward, carving its burrow like a crawling prisoner who digs an underground tunnel with a spoon; or a blind man tapping alone in the wooden dark.

The main diet of the shipworm appears to be plankton and other minute organisms. It remains unknown whether the shipworm actually eats the wood particles it shreds, or merely processes it into a pulpy substance. If the latter, you have to wonder why it expends so much energy
on a task from which it does not specifically benefit. Eating wood is simply its mission, its fate, unquestioned, just as the scholar burrows through libraries, or the writer spends years piling up texts, secreting the unawaited vellum like a series of outer walls between the world and himself.

It would be a lovely revenge to eat “this villainous animal,” as Massuet calls it, even introduce it as a delicacy at the Oyster Bar. Customers might be invited to select their own bunch at a wharf where shipworms are particularly plentiful and bring them to their favorite restaurant, for
Tournedos de teredo.
The celebrated Redi found it very eatable, excelling all shellfish with its exquisite flavor. But Jeffreys thought the smell of a fresh shipworm nauseating. In trying to assess what conceivable utility the shipworm might possess, he concluded dourly, “Perhaps it is one of the creatures made not so much for our use as for our punishment.”

More recently, a chemist named Harold Griffin extracted a bacterium found in shipworms that can be used as a powerful stain remover for laundry detergents. Beyond that, shipworms perform a valuable if unsung service by reducing the amount of driftwood in the oceans. Wood being slow to deteriorate in salt water, shipworms help the process along, unclogging the waterways.

In the early 1970s, when the federal Clean Water Act of 1972 started the improvement of the coastal environments, New York's polluted waters were in fact choked with an excess of rotting wood. “As pier decks and pilings were worn or torn away from their structure, these boards, pilings, and pier components began to threaten the safety of boats navigating in the harbor. In 1974, the Army Corps of Engineers developed a program to cope with the monumental rot of the city's pier infrastructure, the New York Harbor Drift Removal Project,” wrote Carter Craft, in his study
Piers as Public Infrastructure.
Meanwhile the shipworms, awaiting improvements in water quality, were getting ready to do their part. But they have overshot the mark, gnawing through sound and rotten wood without distinction. It has not helped matters that virtually all pier development in New York Harbor has been built on wood pilings.

One is tempted to say that maybe it would make more sense just to let the shipworms do their damnedest, and not even try to hold on to the piers. Millions of dollars would be saved. The problem with that strategy
is that our current environmental laws will not permit any further incursions, be they landfill or construction, into the water, so that once a pier goes, it is lost forever, and with it the potential for being someday utilized as public space. Considering how narrow the Hudson River Park will be in certain stretches, hemmed in by the highway, the piers may afford the only opportunity to have a tranquil experience with the river, unimpeded by auto traffic.

So the shipworm must be stopped. Various coatings have been applied to wooden surfaces over the centuries to safeguard them against the marine borer, from tar to bacon and lime, but the most common wood treatments are creosote and CCA (a mixture of copper, chrome, and arsenate). Effective as creosote and CCA may be, it is now acknowledged that both treatments leach toxic chemicals into the water. Certain types of wood have proven more impervious to the shipworm because of their extreme density, such as rain-forest lumber, but these rare and difficult-to-replace timbers from the Amazon and Central American forests are increasingly placed off limits, as well they should be. You can wrap old wooden pilings in concrete or steel, as is increasingly done with pier reconstruction, though both materials encounter problems in aqueous environments: the former can be corroded by sulphate attack, the latter through oxidation. Stone, the best, most cost-effective material over time, has been neglected because it is the most initially expensive.