Photograph through a microscope of a round section of wood with lots of holes boring into it.
March 6, 2013

The Clam That Sank a Thousand Ships

The clam that sank a thousand ships 

Unless you happen to be chowing down on some steamed clams at the time, a discussion of important influences on human history is unlikely to include a clam as part of the conversation. But the eating habits of one small group of highly evolved clams has altered the travel plans of Christopher Columbus and Sir Francis Drake, changed the outcome of naval battles, and has inspired folklore and poetry. 

Clams are members of the Bivalvia, a relatively diverse subgroup of molluscs that includes about 10,000 living species of oysters, mussels, scallops and any of the typical “seashells” we are used to finding washed up on beaches, whether on fresh- or saltwater. Other molluscs include snails, slugs, squids, and octopus. Bivalves are creatures that have two roughly symmetrical hinged shells (hence Bivalvia from the Latin bi = two, and valva = leaf of a folding door) that usually can enclose the entire animal for protection. Most are filter-feeders, meaning they take in great quantities of water through one siphon, pump it through the gills that strain out small food particles, and then send it out a second siphon. 

Three illustrations of shipworm getting progressively close-up on the front-end.

Old woodcut illustrations of “shipworm” showing the worm-shaped body (B) on the left along with the shell valves at the front (S) and the siphons for incoming and outgoing water to the gills for breathing (IO). The middle figure is a close up of the front part of the animal and the shell valves (S) and on the right is the shell itself, showing its modification into a grinding surface. From Popular Science Monthly, August 1878. 

But bivalves have been around a very long time, over 500 million years, and over that time some strange exceptions to the usual life history have evolved. The two valves of its shell have been modified from protective devices into two small, but extremely effective grinding surfaces at one end that are used to bore into any piece of wood encountered in the ocean. The clam starts out as a small juvenile that settles on a wood surface. As the new small clam bores into its new home, the wood is digested with the help of symbiotic algae that live on its gills. As the hole gets deeper, the animal’s body elongates to maintain a connection to the surface, and the burrow is buttressed with a shell-like lining. 

An illustration demonstrating the growth stages of shipworm, starting from a small hole and growing into a long, curved tube through the wood. As the worm growing further into the wood, two small siphons at the back end remain at the surface of the wood.

The settling of a young Teredo onto a piece of wood and its gradual growth. The shell halves grind up the wood. Note that the siphons remain at the wood surface to bring clean seawater to the animal. Figure from Flingeflung, German language Wikipedia. 

As the common name “shipworm” suggests, and is emphasized by its scientific name Teredo navalis, this species has a long history of damaging ships. Some have suggested that the anxiety of Christopher Columbus’ crew to head west from Europe was not fear of the unknown, but fear of shipworm damage on a long journey, and for good reason. The fourth voyage of Columbus to the Americas in 1502 came to a disastrous end when all his ships sank due to damage resulting from Teredo. His ships were, “… rotten, worm-eaten … more riddled with holes than a honeycomb… With three pumps, pots and kettles, and with all hands working, they could not keep down the water which came into the ship, and there was no other remedy for the havoc which the worm had wrought… my ship was sinking under me…”  (from a letter describing the voyage). Columbus was forced by these small clams to land on Jamaica. He and his crews were marooned for a year before being rescued. 

Left, a painting of Christopher Columbus, seated, wearing dark robes and hat. Right, a painting of Sir. Francis Drake, standing near a table with a globe on it with one hand on his hip. Wearing dark robes and an frilled ruff.

The fourth voyage of Christopher Columbus (left) to the Americas in 1502 came to a disastrous end when all his ships sank because of damage from these clams. In 1579, Sir Francis Drake (right), the famous English pirate/explorer/Vice Admiral spent a month on the Californian coast repairing the Golden Hind, which had been eaten by shipworms. 

In 1579, Sir Francis Drake spent over a month on the Californian coast repairing the Golden Hind, which had been damaged by shipworms. And there are claims that shipworm appetites might have been a factor in the English defeat (more like repulsion) of the Spanish Armada in 1588. The Spanish had remained docked in marine waters off Portugal for several months before engaging the English, providing plenty of time for infiltration of ship’s timbers by the clam that would have weakened and slowed the vessels. 

Three paintings, side-by-side. Left, a formal painting of King Philip II of Spain. Centre, a painting of the panish Armada at sea. Right, a formal painting of Queen Elizabeth I.

Perhaps shipworm appetites helped the English defeat the clam-weakened ships of the Spanish Armada in 1588! King Philip II of Spain (left), was forced to keep his Armada at sea several months (centre) before engaging the navy of Queen Elizabeth I of England (right). 

Even the eventual  addition of copper cladding to naval vessels was not certain protection from the “worm”, as this famous poem by Henry David Thoreau (1817-1862) attests: 

… The vessel, though her masts be firm, 

Beneath her copper bears a worm … 

Far from New England’s blustering shore, 

New England’s worm her hulk shall bore, 

And sink her in the Indian seas … 

-(excerpted from “Though all the Fates” 1849) 

It has been estimated that ship timbers needed replacement every eight years on average, largely due to damage from Teredo wood-boring. At this rate, it is clear that this marine clam has had a tremendous impact on terrestrial ecology, too – huge tracts of coastal forests around the world have been cut down to replace damaged hulls of the ships of all the colonial powers as they travelled the seas. And all that travel introduced these clams all over the world as affected ships brought the animals with them. For this reason, scientists are uncertain of the original distribution and habitat of “shipworms.” 

Photograph of a portion of wood that has had grooves and holes eaten into it by shipworms.

A small portion of wood from the Philippines showing the damage that occurs from the activities of Teredo, a woodboring clam that can digest wood with the help of symbiotic bacteria (MM 2.4-1062). Scale bar is 5 cm. 

Of course, Teredo clams do not only target vessels, but any wooden structure in the sea. In 1731, parts of Holland were flooded because wooden dikes were eaten and weakened by “shipworm,” prompting replacement by costly imported stone. And perhaps Teredo was the cause of (or inspiration for) the famous hole plugged by the little Dutch boy’s finger.  Damage to piers and moorings amounts to tens of millions of dollars per year. An infestation in San Francisco Bay between 1919 and 1921 caused over $2 billion of damage in today’s dollars, and repairing such damage is a considerable cost to this day. 

Photograph of a section of fossil wood with bore lines and remnants of holes across the surface.

Woodboring clams have been around for awhile. This is fossil wood from Souris, Manitoba showing the bore holes of Teredo or a similar species from the Cretaceous Period, about 65 million years old (MM I-2139). Because all existing species require salt water, this suggests that the wood had been floating in an ocean environment before it became fossilized. Scale bar is 3 cm. 

The influence that a tiny bivalve mollusc can have on human history and economic activity is truly astounding. And this is only one of many examples from molluscs, a wonderfully diverse group of animals that is usually well outside our consciousness. Given how some have altered history, perhaps we should give these animals more of the attention they deserve. 

Dr. Randy Mooi

Dr. Randy Mooi

Curator of Zoology

Dr. Mooi received his Ph.D. in zoology from the University of Toronto working on the evolutionary history of coral reef fishes. Following a postdoctoral fellowship in the Division of Fishes of the Smithsonian Institution…
Meet Dr. Randy Mooi

The Arizona-Manitoba Connection

For many Manitobans, the only connection we might have with Arizona involves a certain hockey team that left Winnipeg in 1996 for warmer climes. There are, though, other connections that involve organisms from the natural world other than coyotes as mascots!

I recently returned from a family vacation to southern Arizona where we were hoping to catch up with some of the local bird and lizard specialties, as well as enjoy the truly incredible environment that Sonoran desert has to offer.

View looking out to cacti growing on a desert vista.

What possible connection might there be between the Sonoran desert and Manitoba’s boreal forest?

Two photos side by side. On the left a small bird on a perch. On the right, a lizard on a small rock.

Rufous-crowned Sparrow (left) and Chuckwalla (right), special but expected desert denizens.

Although we were a little early because of the mid-March timing forced by the school break, we had several species of hummingbirds, and I finally managed to see roadrunner – a “jinx” bird that I had missed on previous trips.

Two photos side-by-side. On the lfet a brightly coloured bird with a red beak and on a red perch. On the right, a small fluffy headed brown bird on a branch.

Southern specialties, a Broad-billed Hummingbird (left) and an Ash-throated Flycatcher (right).

Two photos, side-by-side, of small brown birds on the ground amongst foliage.

Lincoln’s Sparrow (left) and White-crowned Sparrow (right), two species that occur in Manitoba but spend time in the Arizona desert, along with (occasionally) Manitoba Museum zoology curators.

Two photos, side-by-side. On the left, a photo of a landscape with low-growing green and brown foliage in front of evergreen trees. On the right, a hand draws aside foliage to reveal a small nest with four blue eggs.

A White-crowned Sparrow nest found in July 2008 at Nueltin Lake, Manitoba near the border with Nunavut, a long way and a very different place than the Arizona desert where they spend part of the non-breeding season. An arrow points to the well-concealed nest in subarctic scrub (left), and the nest with four eggs revealed (right).

So the Arizona/Manitoba connection runs deep on many fronts. Much as humans find a way to chase a puck in the frozen north and the Phoenix desert, our sparrows manage to raise a family in the north every summer and eke out a living in the desert in winter. But unlike the puck chasers, the sparrows haven’t decided to move down to Arizona permanently.

Dr. Randy Mooi

Dr. Randy Mooi

Curator of Zoology

Dr. Mooi received his Ph.D. in zoology from the University of Toronto working on the evolutionary history of coral reef fishes. Following a postdoctoral fellowship in the Division of Fishes of the Smithsonian Institution…
Meet Dr. Randy Mooi

The Bluebird of Halfiness?

A recent web-based discussion about the identification of an odd-coloured bluebird reminded me of a similar odd bluebird in the Museum collections. There are three bluebird species in North America: Eastern, Western, and Mountain. Contrary to what one might expect from their names, Manitoba is home to the Eastern and Mountain Bluebird, the Western being found in Canada only on the other side of the Rockies from us.

Three illustrations side-by-side of different species of bluebirds.

Males and females have different plumages in each species, but at least the males of all three species are quite easy to tell apart when the birds follow the rules and look like the picture in the book (or on the App, as the case may be!) and live where the maps say they must. But, as with so many organisms, variation is the rule, and sometimes things just don’t look quite as they should or show up where they should. That’s why so many people are interested in looking at birds (or insects, or almost any natural organism); they are endlessly varied and can sometimes make unexpected appearances.

 

Image: As early as John James Audubon, the famous 19th century wildlife artist, three species of bluebirds were recognized. Left, Eastern Bluebird, middle top right, Mountain Bluebird (Arctic Bluebird to Audubon), and right, Western Bluebird.

What does this have to do with Museum collections? Because of that amazing variation, the specimens held in a museum are very useful for comparison and the museum collections themselves are a good place to deposit unusual specimens that might need a harder look later. Bluebirds are a good case in point. In the late 1960’s, an ardent bluebird worker in Manitoba, John Lane, found a very strange-looking male bird at one of his nest boxes. Its coloration suggested a hybrid between an Eastern and a Mountain Bluebird. Hybrids among bluebirds were not known at this time, and this was rare enough that he got in contact with the Museum and the unusual step was taken to collect the apparent hybrid, its Mountain Bluebird mate, and raise the young in captivity (for more details, see an article by John Lane in The Blue Jay, 1969, pages 18-21).

The hybrid male bird is certainly strangely-coloured. It has the quality of blue of an Eastern Bluebird, but rather than the typical rusty-orange throat and breast of this species, these areas are mostly blue, similar to the pattern of a male Mountain Bluebird. There are, however, some dashes of reddish mixed in. A look at the back shows the difference in blue colour of the Mountain Bluebird and the possible hybrid and Eastern birds.

Three bird specimens, preserved in a repose pose, with their wings at their sides and bellies up.

A ventral (belly) view of: top, Mountain Bluebird (Sialia currucoides) (MM 1.2-898); middle, possible hybrid (MM 1.2-2486); bottom, Eastern Bluebird (S. sialis) (MM 1.2-1385). Note the blue throat of the possible hybrid with some rusty spots on the breast, and that it is intermediate in size.

Three bird specimens, preserved in a repose pose, with their wings at their sides and backs facing up.

Dorsal (back) view of the same birds as the previous image with Mountain Bluebird above, hybrid middle, and Eastern Bluebird below. Note the quality of the blue is similar between the two lower specimens. Also note that the length of the wings and tail of the possible hybrid are intermediate.

The bluebird species also vary in size, although with overlap. Once the potential hybrid was at the Museum, measurements could be made to see where it might fit. As an example, wing length (measured officially as ‘wing chord’) for male Easterns ranges from 95-105 mm and for male Mountains ranges from 108-121 mm. The hybrid’s wing length, at 104.5 mm is at the high end of Eastern, but nowhere near the Mountain Bluebird size range. This same pattern holds for other measurements.

One possibility not considered by Lane is that the odd-coloured bluebird might be a hybrid of Western and Mountain. Western Bluebirds have a blue throat with an orange breast, and are slightly larger than Eastern Bluebirds, making the measurements fit that species. The blue breast of the hybrid would be the possible Mountain parent contribution. One issue with this is that Western Bluebirds usually have a rusty-orange patch on their shoulder or back, absent on the possible hybrid.

There is one more way that the hybridization question might be resolved with the Museum specimen. Dried skins, like these birds, can provide samples of DNA, the molecules that are the instructions for building and operating living things. Just as human DNA samples can identify a particular person or determine to whom they are related, animal DNA can be used to identify parentage. Perhaps a biologist interested in bluebirds will one day run a sample of DNA and help to solve which species might have hybridized to make our strange specimen.

But without the specimen in a museum collection, we would never have the chance to check.

Dr. Randy Mooi

Dr. Randy Mooi

Curator of Zoology

Dr. Mooi received his Ph.D. in zoology from the University of Toronto working on the evolutionary history of coral reef fishes. Following a postdoctoral fellowship in the Division of Fishes of the Smithsonian Institution…
Meet Dr. Randy Mooi

A Valuable Feather in the Museum’s “Cap”

Tow photos side by side. On the left, a photo of a passenger pigeon specimen. On the right, a photo of a tiny small shell next to a penny for scale, which is it smaller than.

As curators of some sizeable collections (>100,000 in Zoology alone), we are frequently asked what the most valuable specimen or most important one among them might be. Certainly, the collection contains several items that are “one-ofs”, or are the biggest, or most colourful, or even worth a good deal of money in the marketplace. But value, like beauty, is in the eye of the beholder.

 

Image: Who is to say if a specimen of Passenger Pigeon (Ectopistes migratorius) (MM 3.6-887), a species extinct since 1914, is more valuable than one of the tiny Lake Winnipeg snail (Physella winnipegensis) (MM 2.4-6514), a disputed species found only in Manitoba?

We recently received a request for a few feathers off of a single specimen of Ivory Gull (Pagophila eburnea) collected north of The Pas in 1926, the only specimen we have of this species. The Ivory Gull is a High Arctic breeder that has made an appearance in Manitoba only about a dozen times in the last 100 years. The species is listed as Endangered in Canada and its populations are declining. A research group is examining levels of mercury and stable isotopes of carbon and nitrogen in feathers to investigate the possible role of heavy metal contamination and changes in foraging behaviour in Ivory Gull decline. The Manitoba Museum specimen is one of only about 150 specimens from Canada in all the museums of North America, and its age makes it particularly valuable for reconstructing historic levels of contamination and isotopes. Who could have predicted the value of this Museum specimen for conservation of the species when it was collected those many years ago?

An ivory gull specimen posed in repose with its wings positioned in repose as it lies on its back.

Our Ivory Gull specimen (Pagophila eburnea) (MM 1.2-941) from north of The Pas, collected in 1926. Feathers from this specimen can help determine historical levels of pollutants and ratios of stable isotopes can determine feeding ecology.

By sharing information on Museum rarities with researchers who can pool data from the few specimens available in collections from around the world, we learn more about the biology of the organism, making the specimen more ‘valuable’ in terms of information and helping conservation efforts. The Museum ends up with another story to tell about its collection and about the animals themselves. Science, the Museum, and, most importantly, the animal will all win from this exchange.

Nature generally can be understood through patterns. Unique observations, like a rare gull found north of The Pas in 1926, are curiosities, but can’t contribute very much to the bigger picture as an isolated event. Even the proverbial apple clunking onto Newton’s head, though important as a unique event, only becomes truly valuable when its act of falling towards Earth can be generalized to explain why other things also fall.

This helps to explain why the Museum has, when possible, more than one example of a species, and continues to grow collections through active collecting. Just as a single letter is more as a part of a word, or a word is more meaningful when put into a sentence, a specimen becomes more in the context of a collection. A particular specimen does have value in and of itself as a record of occurrence in a single place at a single moment (called a voucher), or sometimes even has monetary value. But several specimens from different places collected at different times provide a more complete story of species variability, distribution, biology, and, as in the case of Ivory Gull mercury levels, how these might have changed over time and space. Each individual provides a data point, and an important one, but the real value comes from the collection as a whole. And a new specimen added to the collection today, while not necessarily individually significant right now, might be so 100 years from now, just as the Ivory Gull specimen collected in 1926 is valuable today.

Open storage drawers showing many preserved bird specimens.

The Museum collections often include several specimens of the same species to include examples of males, females, and juveniles during different times of the year, different locations, and different decades.

A row of open drawers showing a variety of preserved mammal specimens.

These drawers of dozens of the same species of mouse are waiting patiently to tell their story of change over time; change in distribution, ecology, and other aspects of biology.

Richard Fortey (a paleontologist at The Natural History Museum, London) suggested that natural history museums are the archives of the Earth, an apt metaphor. Through their collections, museums document individual “events” as specimens, which together tell the story of how our natural world changes over time. The Manitoba Museum plays this critical role as natural history archive for the province. Specimens old and new are together a feather in our collective cap.

Dr. Randy Mooi

Dr. Randy Mooi

Curator of Zoology

Dr. Mooi received his Ph.D. in zoology from the University of Toronto working on the evolutionary history of coral reef fishes. Following a postdoctoral fellowship in the Division of Fishes of the Smithsonian Institution…
Meet Dr. Randy Mooi

Anniversary for a Museum Outlaw

Just outside my office on the 4th floor of the Museum is a big, hairy outlaw that can stare anybody down. It’s the mounted head of one of the original ‘outlaw buffalo’ of the Pablo/Allard herd of Plains Bison (Bison bison bison), the most significant of the private herds purchased by the Canadian government that helped to bring these magnificent animals back from the brink of extinction.

A taxidermized bison head mounted on a large, oval, wooden wall mount.

By 1890, it is believed that there were no bison remaining in Canada. Several private herds started from wild stock during the 1870s were obtained by the Canada government beginning in 1897. The Pablo/Allard herd, the origin of the Museum ‘outlaw’, had its beginnings in about 1872 when Walking Coyote, a member of the Pend d’Oreille First Nation, captured a handful of animals south of the Alberta/Montana border. About a dozen offspring of this group were purchased by Pablo and Allard in 1883 and augmented with others purchased from other private owners some ten years later. When protected and left to their own devices, this bison herd became quite large.

 

Image: The 4th floor Museum ‘outlaw’, an original member of the Pablo/Allard bison herd, but one of several that refused to be driven into a train boxcar for shipping and was shot for its obstinance. Times have changed, we’d like to think.

Michel Pablo rounded up his bison in Montana, loaded them onto boxcars and sent over 700 to Canada between 1907 and 1914. However, there were a few individuals that were too wild and managed to escape. In early 1911, in what was billed by the The New York Times in January that year as “the last big buffalo hunt in the history of the world,” Pablo hunted down and shot these ‘outlaw’ bison. The metal plaque on the Museum hallway head clearly identifies it as a member of Pablo’s ‘outlaw’ herd.

Newspaper clipping reading, "LAST BUFFALO HUNT NOW ON / Michel Pablo Killing Off His Herd In Spite of Montana Authorities. / Special to The New York Times."

The New York Times headline of January 22, 1911 reporting the culling of the ‘outlaw’ bison.

Close up on a metal plaque at the base of a wall mount reading, "Fine Specimen Head of Buffalo Bull of Pablo Herd of Outlaw Buffalo - 1912. / Property - City of Winnipeg".

The metal plate identifying the Museum bison head as an ‘outlaw buffalo’ of the Pablo herd.

I mentioned the Museum bison head mount to a volunteer in Geology and Paleontology, Dr. Jim Burns, who has a fascination with Winnipeg history. He brought to my attention a photograph he had researched that showed 11 bison heads lined up on Main Street in 1911, apparently from that famous last hunt by Pablo (see Burns, J.A. 2010. Edward Darbey, taxidermy, and the last buffaloes. Manitoba History, 63:40-41). It seems that a number of these animals had made their way to a well-respected Winnipeg taxidermist, Edward Darbey. Born in St. Thomas, Ontario in 1872, Darbey came to Winnipeg at the age of 15. In 1898 he purchased the taxidermy shop on Main Street that is the backdrop to the bison skulls in the photo. By 1902, Darbey had been appointed as the “Official Taxidermist of the Manitoba Government,” an odd title by today’s standards, but one that made sense at the time when animal mounts were frequently used to decorate public buildings.

The Pablo bison were hunted in early 1911, the bison head and taxidermy shop photo was dated by Dr. Burns to around mid-1911, and there is record of a Winnipeg auction of bison head mounts and capes in late November, 1911. According to the plaque on our Museum mount, it became property of the City of Winnipeg in 1912, a reasonable date to link it with the somewhat gruesome Main Street display.

Eleven bison skulls posed infront of and atop sandbags in front of a the E. W. Darbey Taxidermy shop.

Eleven bison skulls outside Edward Darbey’s taxidermy shop on Main Street in Winnipeg, mid-1911. Photo courtesy of the Archives of Manitoba through J.A. Burns.

A close up on the upper portion of the skull and the horns of a bison skull. "#5" is written along the top of the skull.

A close-up of the horns of one of the skulls from the 1911 Main Street photograph. Enhancing images like this provided a way to compare the horns of the undressed skulls with that of the Museum head mount to see if it could have been one of these animals.

Two close ups of left-side bison horns. On the left side is a black and white photograph of a horn on an undressed skull bearing very similar markings to the horn on the right side image, which is a colour image of a horn on a taxidermized skull.

Enlarged images of the undressed skulls in the old photo show distinctive patterns on the horns. I spent some time photographing the horns of the hallway ‘outlaw’ at similar angles to those of the 1911 photograph. From careful comparison, I am reasonably certain that there is a match for our 4th floor ‘outlaw’ – skull #5, second from the right in the back row of the Main Street photo (just right of the bottom of the door to the shop). The numbers on the skulls likely linked them with the appropriate skins for later mounting.

 

Image: A comparison of the left horn of skull #5 from the 1911 photograph (left) with the left horn of the Museum ‘outlaw’ mount. Although difficult to discern on the low resolution images here, patterns on each of these horns and also the right horns are strikingly similar, suggesting a match.

So our big, hairy ‘outlaw’ bison mount is 100 years old this winter. This could be considered a depressing anniversary of the killing of some of the last ‘wild’ bison in North America. But for me, the old head commemorates the beginning of an incredible conservation story, the salvation of our provincial emblem and, just perhaps, an altered attitude of society towards the world around us.

Dr. Randy Mooi

Dr. Randy Mooi

Curator of Zoology

Dr. Mooi received his Ph.D. in zoology from the University of Toronto working on the evolutionary history of coral reef fishes. Following a postdoctoral fellowship in the Division of Fishes of the Smithsonian Institution…
Meet Dr. Randy Mooi