Where
Recently I started scanning my images of scaphopods, an animal group from which very few people have seen living animals. I did a lot of research on them actually starting about 1975, and becoming intensely active in 1983 and finally winding down about 1997. I still have a paper or two to write but I haven’t done any field work in a long time. I described two deep-sea species (1, 2) from specimens sent to me, but most of my work has been done on the scaphopods found in the shallow waters of the Northeastern Pacific. Scaphopods are particularly common in many of the fjord environments north of the Strait of Juan de Fuca. I spent some small amount of time examining their distribution in the waters of Northern Puget Sound, particularly in the northern American San Juan Islands. In this area, two species of scaphopods, Rhabdus rectius and Pulsellum salishorum are found, and may be reasonably common in a few areas. There a couple of marine research laboratories/field stations in that region, but as far as I know, I am the only person in the last half century who has worked at one of those labs and done any kind of research on scaphopods.
During the period from 1981 until 2003, I taught at various times at a Canadian marine station located in Bamfield, British Columbia, situated on a small inlet on the southeast side of Barkley Sound, a large fjord system on the west side of Vancouver Island. This marine laboratory, known as the Bamfield Marine Station from its beginning in the 1970s until it morphed into the Bamfield Marine Sciences Centre in the early 2003, offers easy access to some of the scaphopod habitats of the Barkley Sound region. For the two-year period from September of 1983 until September of 1985, I was the Assistant Director of the marine station, and actively carried out an intensive project on scaphopod ecology and natural history. Subsequent to that time, I worked up data collected during that period, as well as initiating other scaphopod work, mostly with specimens sent to me by various researchers. As a result, I have published about a half dozen research papers on scaphopods, and have a couple of more in the works… if I can only get my act together enough to finish them.
The Critters
Scaphopods, or “tusk” or “tooth” shells are mollusks that live as subsurface predators in the marine sandy or muddy sea bottom. Covering an estimated 60% of the planetary surface, this is THE largest habitat in on the planet’s surface. As the scaphopods are either abundant or dominant predators in this habitat, that makes them some of the most ecologically important animals.
By last count there are about 8 to 10 people living today who have published papers on scaphopods, which may make them the most understudied of all important marine animals. Given that a number of those people are museum workers whose entire conception of the Molluscan Class Scaphopoda is that it is a collection of oddly shaped shells, it is evident that the world-wide scientific interest in the group is probably so close to nil as to be statistically indistinguishable from it.
This means that to a very real extent, that anybody who works on scaphopods as a full, or even part-, time venture is on their way to committing, or has committed, scientific/academic suicide. While it is true, to paraphrase one of my old profs, “If only five people work on your group, you can’t be ranked any lower than the fifth most prestigious worker on the group.”
However, if only five people work on your group of interest, it means nobody will care what you write. So, the good side is that everybody working on the group knows who you are. On the other hand, nobody else in the world – or known universe – cares who you are or anything about the animals… If there is so little interest in group worldwide, no matter how good your publications are, they will simply disappear into the large black cesspool of unread papers as nobody will care about you write.
Well, who am I to argue? I will state, however, in my defense, after that statement that I am the senior author of the definitive reference about the animals published to date: Shimek, R. L., and G. Steiner. 1997. Scaphopoda. In: Harrison F., and A. J. Kohn, Eds. Mollusca II. Microscopic Anatomy of the Invertebrates. Volume 6B: 719-781. Wiley-Liss Inc. New York, NY. ISBN 0-471-15441-5. Whooopty-doooo…
Five species of Scaphopods found in the Barkley Sound region of Vancouver Island, British Columbia, Canada. The scale bar is in millimeter.
From top to bottom, Pulsellum salishorum, upper two rows, females on the left, males on the right, next single row, Cadulus tolmiei, female left, male right, below that species is a single row of two Gadila aberrans, female left, males right, The next two individuals are Rhabdus rectius, female on the top, male on the bottom, and the lower-most individual is a single specimen of Antalis pretiosum (formerly Dentalium pretiosum), the “Indian Money Shell.” These individuals were alive at the time, and in the high definition of the moment, the top four species have shells that are thin enough to be translucent, and the gonads from each gender are differently colored, so I could discrimate the sexes. It is hard to see in the low res image here, but if you look at the top animals on the left, you can see a hint of pink in the shell, and that is the color of the ovaries of Pulsellum salishorum.
Heretofore…
Scaphopods were very economically important animals in the North American native cultures. Given the common name of the “Indian Money Shell,” one species, at one time called “Dentalium pretiosum,” was collected and traded throughout large parts of Northern North America. Here is an image from a National Geographic Magazine article about the trade; I was a technical advisor to the NGM for that article. The scaphopods were harvested in by some of the tribes from the Pacific Northwest, both in what would become Canada and the U.S. There are numerous “tales” about how the shells were collected, and at least two different and likely ways of collecting them. Knowing what I found out about the habits of that species (now called Antalis pretiosum), it appears that very few of the actual living animals were collected, but rather shells containing small hermit crabs the primary source of “scaphopods.” There is a hermit crab in the region were the scaphopods are found that is not coiled to fit into a snail shell as are most hermit crabs, rather this one, Orthopagurus mimumus, has a straight body and lives preferentially in the large “dentalium” shells. The crabs crawl around on the surface of the habitat, while the living animals are generally deeply under the surface, at least a foot (30 cm) below the water/sediment interface. In fact, the living scaphopods all have a rapid burrowing response – an exposed scaph is a dead scaph – as crabs and fish eat them. In text books and references, they are often illustrated as having their pointed ends exposed from the sediments, and some are found this way, between1 in 60, to 1 in about 10,000 depending on the species I have looked are exposed at any one time. So much for the standard references… More about why this should be so in my next issue of this blog.
Anyway, one of the more recent “proofs” of the hypothesis that it was mostly dead scaphopod shells inhabitated by hermit crabs that were collected actually comes from one of the National Geographic Magazine sites. They have a series of images purported to be Antalis pretiosum, all of dead scaphopod shells taken by David Doubilet, and all showing hermit crabs showing hermit crabs in the shells. Doubilet was apparently in search of the wily dentalium and, by golly, he got some pictures of it… or at least of its shell. Interestingly enough, there is an image also on their site showing Antalis pretiosum feeding below the sediment surface. This wonderful image is a painting by Gregory A. Harlin, and it clearly shows that scaphopods don’t have legs… Of course, Doubilet didn’t look at the painted image. One further note that adds even more humor to this bit of fubardom (fubar = fucked up beyond all recognition) is that Harlin’s painting was done for the previously mentioned earlier article in NGM about the dentalium trade for which I was a technical advisor. Harlin based his painting on my drawing of Rhabdus rectius feeding below the sediment surface that was used in Shimek and Steiner, 1997.
A diagram of Rhabdus rectius shown in its feeding posture below the sediment surface, drawn in life from animals in aquaria. Compare with the painting by Gregory A. Harlin,
The dentalium shells collected on the coast were traded through out North America, at least as far east as the Great Lakes and were quite valuable. They were used in the construction of jewelry and as ornamentation on clothing. I have read, with no real estimate of the validity of the statement, that one or two of them could be exchanged for a tanned buffalo hide. Consider that when you look at the image I have imbedded below.
Plains Indian neck ring jewelry in the collection of the Burke Museum,University of Washington, Seattle, Washington.
It has been reported, that given that the shells of the animals were quite valuable, it stands to reason that the one of the first things the Europeans did (in the guise of the Hudson’s Bay Company) was to “devalue the currency” by flooding the market with “counterfeit” shells. When the HBC traders began to realize how valuable the shells were, they sent word back up the communications chain, and European shells were harvested in some relatively great numbers. The European species, Dentalium entale, is/was essentially identical to Dentalium pretiosum and easily collected (and remember, both are now in the genus Antalis). These were sent to HBC traders throughoutNorth America and used to purchase all sorts of trade goods. So many shells became available that this sufficiently brought the value of the shells down so low as to make them worthless as trade goods for the coastal tribes as they could not harvest enough to get the traditional materials (such as buffalo robes, and they became dependent upon the HBC to sell them blankets). If this is true, it is a great (?) lesson in market economics…
More on scaphs later….
Until then…
Cheers, Ron
