Posts Tagged ‘scaphopoda’

A Pentamera-Dominated Sandy Environment

Wednesday, August 29th, 2012

The Place – Where, When, Why.

The American San Juan Islands in the Northern Puget Sound. Waldron Island is at the top (North), CB = Cowlitz Bay. The Friday Harbor Laboratories location is indicated by the colored star on San Juan Island.

Cowlitz Bay, Waldron Island, Washinton. Viewed from the north, July, 1976. The primary study area is indicated in blue, the rocky reef used for orientatioin is indicated in yellow.

Cowlitz Bay of Waldron Island, Washington initially attracted my attention in the early 1970s as the result of a collecting trip undertaken out of the University of Washington Friday Harbor Laboratories (FHL) as part of my doctoral dissertation research.  These trips used a converted fishing boat which was configured to pull a “biological dredge”, which is effectively a metal frame with some sort of netting attached to retain the catch.

M/V HYDAH
Operated under contract to the University of Washington’s Friday Harbor Laboratories, this was the boat I used for dredging in the 1970s. Photographed in San Juan Channel, July, 1976.

This dredge is lowered to the sea floor and pulled along it for some, supposedly, known distance.  Depending on vessel’s velocity, the configuration of the dredge frame, and the substrate,  the apparatus will – optimally – dig into the bottom and collect a sample of that bottom along with what is in it.  The dredge is returned to the surface, emptied on to a “sorting table”, typically, a large box-like apparatus which contains the sample.  The sample is rinsed and organisms of interest are collected.

Samples collected in this manner by oceanographic vessels using well-designed dredges can be taken in a reasonably precise manner.  For example, if the apparatus is pulled at a given speed, it will dig into the bottom of a certain type to a known depth.  Our samples were nowhere near as well-controlled!  In shallow waters, 60 to 200 feet, we could be reasonably sure of getting something.  At other times, it was quite feasible to have the dredge hang up on an underwater obstacle  no sample would be obtained.   Very occasionally the apparatus could be lost, along with all of the cable pulling it.  This latter proposition is, at the very least, expensive and, at least to the person in charge, embarrassing.  Consequently, one had to choose one’s dredging sites with care, and hope that the boat driver knew what he/she was doing.

To help pay for my studies, I applied for and was awarded what at the time was referred to as an National Science Foundation doctoral dissertation grant.  As part of the grant, I requested funding to explore habitats in the region for various of the turrid gastropods I was studying.  I used these funds to pay for dredging trips to the soft sediment habitats that nobody else was really interested in investigating.  I would sort through the materials obtained by the various dredges and if I found some of my “target” snails, and if the area seemed otherwise interesting and diveable, I would try to do some diving in the area and ascertain the habitat first hand.

I chose to dredge in Cowlitz Bay because it was off of the beaten track.  Most of the dredging trips out of the FHL went to the same places over and over, ignoring other areas both near and far from the labs.  As I could readily get information from the commonly dredged places, I decided to spend my grant’s money to go elsewhere.  I didn’t find much in the way of turrids in the dredging results from Cowlitz Bay, but I did find some live scaphopods, Rhabdus rectius, to be exact.

Scaphopods, 3 species commonly found in the Pacific Northwest. Gadila aberrans is not found in Cowlitz Bay, the sediment is unsuitable, and the salinity is likely too low.

As I had an abiding interest in scaphopods  predating my interest in turrids, I later spent some relatively intensive field work looking at the scaphopods and other critters found in the bay.  I did over 30 dives in Cowlitz Bay, most of them with my friend, Dr. F. Scott McEuen, as my diving partner.  Our objectives, on many of these dives, were doing various types of quantitative sampling, either doing transect surveys or collect samples for later laboratory analyses.  On other dives, we simply took pictures.  Scott was investigating the sea cucumbers in the genus Pentamera which are found there in absolutely mind-boggling numbers, and I was looking at the scaphopods whose abundances, while significantly less than boggling, were still high enough to make sampling worthwhile.  Additionally, there were a lot of other interesting things of one sort or another, either in the bottom, on the bottom, or swimming above the bottom of the bay that served to tweak our collective or individual fancies bringing us back to the bay time and time again.

Sea cucumbers in the genus Pentamera in the substate in 20 feet (6 m) of water in Cowlitz Bay in July, 1977. Juveniles of the year have just settled, but are too small to see in this image; all the cukes that are visible are adults. The cucumber population density is in excess of 50,000 animals per square meter.

The Place

This large west-facing embayment opens toward the west.  Most of my diving was done in the northern half of the bay.  There is an underwater ridge running more or less east-west located in the middle to eastern portion of the bay, about one third of the distance from the bluffs forming the southern edge of the bay to the spit of land forming the northern edge.  The ridge has a kelp bed growing from it, so to orient ourselves when we arrived, we would find the kelp bed and go north in our boat until we had covered about half the distance to the northern shore.  There we’d anchor, typically in about 60 feet (18 m) of water.  When we anchored we were a long way from any shoreline, easily a half mile (700 to 800 m), and on cold, drizzly, gray winter days, it seemed a lot further.  This meant that when we hit the bottom after following the anchor line down, we took careful compass bearings so that when we needed to surface we could find our way back to the vicinity of the boat.  Or at least that was the plan.

The substrate in the area was sand or sandy-mud and was generally gently sloping to the west or south.  The deepest we normally swam to was about 90 feet (27 m), and most of our dives were between 20 to 60 feet (6m to 18m). Occasionally, we did a dive in the shallower eastern reaches of the bay.  Over the course of several years, I made dives in this region in every season, and what I will discuss in this sequence of blog articles is a summary and compilation of my diving logs from all of the dives.

Near-shore shallow waters of the NE Pacific are tremendously influenced by the local climate.  The annual cycle is worth mentioning here, as I will discuss details of it in passing.  It is not too much of a stretch to say, “Everything depends on the weather”.  Undoubtedly, climate change is affecting the subtidal communities of this region; while I can guess some of the changes due to global alterations, I don’t think that is a profitable course of action.  These images were taken in the period from about 1976 through 1986, and I will use the observations I made at the time

The Seasons

The seasons of the marine shallow subtidal habitats in this part of the Pacific Northwest region, basically the shallow waters of  Northern Washington, British Columbia, and Southeastern Alaska, bear only a passing resemblance to the seasons likely to be encountered above the waterline (Table 1).  As with the terrestrial environment, the primary driver of seasonality is sunlight, but sunlight’s effects come in pure and modified forms.  Pure solar illumination is really pretty uncommon in this region, and typically is found mostly in the summer; generally these bursts of sunlight result in phytoplankton blooms that degrade visibility significantly.  The blooms tend to alternate, in  textbook fashion, with periods of very clear water, probably due to zooplankton blooms.  When we were diving in this area, the visibility we would expect was predictable most of the year, but in the later summer, as the old carnie saying goes, “You pays your money and you takes your chances.”

The rest of the time, sunlight is filtered and muted through clouds.  While solar illumination is, of course, the ultimate driver for the region’s weather both illumination and weather events working together results in the overall marine environment of the entire region exhibiting remarkably stable physical conditions.  Temperature variations below 16.5 feet (5 m) are minor, seldom varying by more than a couple of Celsius degrees, and generally no more than about 6 or 7 Fahrenheit degrees.  Salinity fluctuates much more drastically due to the rainfall and runoff from snowmelt, but even so, deeper areas, below 10 m (33 feet) remain reasonably stable.  Freshwater layers due to major runoff events such as floods tend to flow out over the more stable underlying areas.  This is not to say there are no effects due to these factors, but major salinity and temperature effects are abnormal, variable in extent and degree, and relatively unpredictable.

Table 1.  Subtidal Seasons Of Cowlitz Bay,

And

The Northern San Juan Islands, Washington. 

Season

Starts

Ends

Cause

Manifestation

Dark

Mid-October

Mid-February

Low Illumination, Cool Temperatures

“Everything is shut down”

Clear water, no plankton

Diatom

Mid-February

Early-March

Increasing illumination and temperature, Nutrients from spriing runoff increase

Substrate becomes covered with a thick diatom coat.

There is clear water with scarce plankton.

Filter-feeders start emergence

First Plankton

Early-March

Late-March

As Above

Phytoplankton blooms;

Water becomes greenish and visibility drops;

Substrate diatom layer becomes thinner;

Some benthic herbivores present; 

Filter-feeders emerged.

Second Plankton

Late-March

Late – May

As Above

Zooplankton bloom becomes noticeable;

Phytoplankton presence is less, Water visibility increases slightly,

Water color changes from green to gray-green/aquamarine;

Spawning is occurring with some benthos,

Diatom cover is largely gone,

Benthic herbivores are common.

Settlement

Late – May

August

Nutrients from runoff become less, Illumination and temperature still increasing

Small animals and settled juveniles become very common. 

Plankton pulses, going from phytoplankton dominated to zooplankton dominated to no plankton (clear water) in short (week long) sequences; 

Water often cloudy, greenish white.

Growth

August

Early- October

Runoff absent,  Illumination begins to drop, Temperature peaks.

Filter-feeders evident;

Benthic predators very active. 

Diatom cover almost gone. 

Small predators disappearing.

Shutdown

Early October

Mid to LateOctober

Temperature drops, Illumination drops, Rains begin.

Plankton disappears;

Filter-feeders shut down. 

Water clears up, becomes dark green.

Diatoms on benthos gone.
 
 
 
 
 

The Current Conditions Are….

Cowlitz Bay, as in the rest of the San Juan Islands, has semidiurnal tides which generally have a pattern of two unequal high tides interspersed with two unequal low tides.   The tidal cycle is primarily driven by the lunar cycle, and the relative magnitudes of the highs and lows fluctuate through the year following the lunar calendar.   The most extreme tides, the largest difference between the higher high and the lower low tides, are found near the solstices, while the least extreme tides are found near the equinoxes.   The differences between the most extreme tides is reflected in the  velocity of water currents, and the unconsolidated substrate in the bay belies the rather strong currents that may occur there.

Coming up next… the animals and interactions.

 

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Predators In The Sand, Or…

Monday, September 5th, 2011

Thoughts On The Evolution And Natural History Of Scaphopods.

Why Here And Why Now?

This post is, obvously, the continuation of a series dealing with scaphopods and some  of the data I will be posting subsequently are also to be found on one or another of my website’s scaphopod pages.   However, these blog entries are not strictly duplicative; I have added a number of new data and I have  altered some of  the information to reflect my present thoughts.   Some of the ideas and data to be  presented here are somewhat iconoclastic, and contrary to what some authorities have proposed.  It is unlikely I will get the opportunity to publish these ideas in more formal, peer-reviewed, jounals, and as a result I thought this is an appropriate place to let the ideas see some glimmer of the light of day, albeit dimly and through some wet mud.  To the questions of “Why Here and Why Now?”  I think the reasonable answers are, “Because I think  this is an appropriate place and it is time.”  Or phrased another way, “Why Not?”

 One of Three Groups…

The scaphopods are the last of the classical molluscan classes to show up in the fossil record, with arguably the first unequivocal scaphopod being Rhytiodentalium kentuckyesnis Pojeta & Runnegar, 1979.  However, this unequivocality is not likely the case; the specimens of Rhytiodentalium are all significantly altered fossils, and from personal examination, it is impossible to tell exactly what they are.  Although some of them match the general shape of modern – and presumably – highly derived scaphopod shells, these “shells” appear to be comprised of small pelletized material.  It is unclear if these pellets are the result of significant or minor diagenesis.  In the first case, the shells could considered as scaphopods.  In the second, they would have to be something else, perhaps, some sort of worm tube.  I think the latter is much more likely than the former.

The term “armchair quarterback” has been coined to describe those individuals who after watching a football game at home on the “aptly-named” boob tube, dissect a quarterback’s performance and describe, a posteriori, what he should have done.   Of course, such a critique, if that’s what it may be called, is done without the experience of being under the tremendous pressure of the momnet on the field of play, without the sport’s equivalent of the “fog of war” clouding information input and, most importantly, it is done with the precision vision of hindsight.  Of course, in the armchair experience, errors made on the field become glaringly obvious.   One of the prime theories of scaphopod evolution is that scaphopods arose from an ancestor that either was in the extinct class, Rostrochonchia, or pehaps in its ancestral group, is the malacological equivalent of such airchair quarterbacking, however, with one glaring exception.  It is undoubtedly wrong, most likely as a result of being proposed by individuals who have had no experience examining or studying live scaphopods or, indeed, live animals of any sort..

There are a number of very serious problems with the Scaphopods from Rostroconchs derivation, not the least of which is that the scaphopod shell is univalved and tubular, while the rostroconch shell is bivalved of various non-cylindrical shapes.   Additioanally, the scaphopods are all predators or scavenger/predators; as a result, they must move; no predator on infauna waits for the prey to come to it.  Then, the scaphopod radula, the structure used to macerate, break, crush  or smash prey is the largest radula relative to the adult body size in all the mollusca.  On the scale of the organisms, it is a truly massive structure.   This massive radula is presumed to have been derived from an ancestor in the same group that is supposed to have given rise to the bivalves.  However, not only do the bivalves  lack the radua, but also any remnant of the head it is found in.  While the scaphopod head is reduced and kept within the shell, it is present, and has a relatively large brain, also a structure missing in the bivalves – and presumably their rostroconch ancestor.  The rostroconch shapes vary quite a bit, but one thing that is evident in all of them is that they are not streamlined and capable of easy movement through sediments.   Indeed, with the shapes typically found  in rostroconchs, it is quite likely, that like some oddly shaped infaunal bivalves today, they did not move at all as adults.  Scaphopods, on the other hand, are all mobile and many of them, given the appropriate stimulus, are capable of bursts of relatively rapid motion, after which they often stop, construct a feeding cavity and feed.  Given the sizes of the adult scaphopods, the  number of body lengths that they are able to move in any given amount of time, and the media that they move through, it is quite reasonable to consider many of them to be “high speed” predators.  Finally, recent molecular genetic work shows them to be grouped with the cephalopods, not the bivalves.

I think it is likely that one of the first branchings of the ancestral molluscan stock gave rise to a predatory organism that had a tendency to develop or elongate in a dorso-ventral direction.   In turn, this ancestor, over time, gave rise to three successful clades, eventually leading to the crown groups of the cephalopods, gastropods, and scaphopods.  All of these groups are all characterized by dorso-vental flexing in the visceral region, a well-developed radula, and elaborations of the cephalic tentacles.

Each of the three dorso-ventrally flexed groups shows particular adaptations and modifications for its primary habitat.  The cephalopods are highly successful predators in the pelagic enviroment.  Gastropods have radiated into virtually every possible niche except aerial flight, and are found in all terrestrial, fresh-water, and marine environments, although their ancestral habitat was the marine benthic epifaunal environment.  Scaphopods have become highly adapted for predation on organisms living in unconsolidated marine benthic sediments.

Cadulus tolmiei in situ, modified from Poon, 1987.

The above image shows Cadulus tolmiei feeding in sediment, cb= captacular bulb, dd= digestive diverticula, fc = foot cavity, g = gonad,  m= mantle,  pa = posterior aperture,  s = shell,

References:

Pojeta Jr., J. et. al. 1972. Rostroconchia:  A New Class of Bivalved Mollusks. Science. 177: 264-267.

Poon, Perry A. 1987. The diet and feeding behavior of Cadulus tolmiei Dall, 1897 (Scaphopoda: Siphonodentalioida). The Nautilus: 101: 88-92.

Steiner, G. and H. Dreyer.  2003.  Molecular phylogeny of Scaphopoda (Mollusca) inferred from 18S rDNA sequences: support for a Scaphopoda–Cephalopoda clade.  Zoologica Scripta. 32:343-356.

More to come…

Until then,

Cheers!!!

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More Scaphopod Information – Including Some Ancient Scaphopod Jewelry

Friday, August 26th, 2011

 Scaphopod Connections

Over the past few days, I have finished scanning my images of Native American scaphopod jewelry and decorated clothing, all of which were photographed in 1987 in the Burke Museum on the University of Washington campus in Seattle.  Some of the Native American dentalium jewelry/clothing images that I have are REALLY impressive, not only for the wealth they contained, but also for the tremendous skill of the remarkable women who made them.  Somehow, I wish I could find something like the shawl in the image below in an old trunk in my garage, and take it to the appraisers on The Antiques Roadshow.  It would get the attention it really deserved.  Ah… well.  All I am likely to find in old trunks in my garage is old trash covered in old dust.

 A shawl, made by a seamstress and master craftswomen from one of the Plains Tribes, in the mid-to-late 19th century.

This is a shoulder wrap or some sort of vestment, I neglected to photograph both sides in 1987, when I took the image.  I would estimate that there may be close to a 1000 Antalis pretiosum shells in this item.

Not surprisingly considering their shapes and durability,  scaphopod shells were widely used in ornamentation elsewhere and elsewhen throughout history.   The following image was taken by Don Hitchcock in from the Dolní Věstonice Museum in the Czech Republic, which has some wonderful artifacts recoverd from an ice age mammoth hunter’s site.  

dolniimg_2014b

A reconstructed necklace made from fossilized Dentalium badense shell fragment artifacts recovered at the Dolní Věstonice site in the Czech Republic.  The artifacts at this site have been dated with Carbon-14 to about 29,000 years ago.  Photo: Don Hitchcock donsmaps.com“

In one of the more bizarre coincidences I have had recently, I found the above image and information with the assistance of Mr. Google and associates.  I hadn’t seen it prior to findinig on the web, but I knew that there should be ancient European, Asian or African dentalium work illustrated somewhere on the web, and charged ahead to find something I might use.  I found this image, and it fit the bill of what I wanted, and I went to track down some information about it, including where the Dolní Věstonice site (which, from reading the information at the site, I realized I must have read about it sometime ago, I recollected nothing at all about it ) is located. 

This Google Earth image shows where the Dolní Věstonice site is located.  The other site indicated, the Frydek-Mistek region, is  where my ancestors, at least back to before the mid-1700’s, lived. !!!  My great-great-grandfather was one of four brothers that migrated together from this area to the US (Texas) just after the Civil War.

Nobody knows, of course, what happened to the descendents of the people who made and used the scaphopod shell necklace, or even if they left descendents at all.   But I think it could be possible -stretching possibilities very thinly- if those descendents remained in that area, that maybe some of the genes of the person who made the scaphopod necklace may have decended to be in the genome – some 28,000 years later – that directed the growth of my scaphopod-studying body.

In closing this entry, I must thank Don Hitchcock for his gracious permission to use his fine image of the scaphopod necklace.  Don has an immense array of web information about the paleolithic period throughout the world, and I have linked to his site in my blogroll.  It is well worth a visit.

Until later,

Cheers,

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Scaphopods

Thursday, August 18th, 2011

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

 

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