To Pen A Tale Of Pens…

September 28th, 2011

Life History

The term “life history” is really a misnomer.  What the term really means is the generalized “story” of an average individual’s life.  Probably the animal whose life history is best known is the human.  Broken down by geographical region, and other demographics, it is possible to predict with surprising accuracy the life span, as well as the major life experiences, such as the number of offspring, and when they occur, for the average individual of many human populations.  In the case of humans, the driving force for the accumulation of such knowledge is not the desire for “abstract knowledge,” but rather the desire to make a profit.  On such knowledge is the insurance industry built, and it is based to a great extent on studies of human life history profiles extended to the greatest precision possible.  We also know the life histories of a large number of other, mostly terrestrial, organisms.  In these cases, biologists have spent a great deal of time studying populations of these animals and have noted when the animals are born, when they die, how long they live, when they mate, and so on.  All of these data can be massaged and manipulated statistically to provide a good understanding of the essential experiences of an average member of those species.  

However, once we pass out of the terrestrial realm and into the oceanic environment, our ability to see all of the relevant aspects of any given organism’s life is significantly obscured by a wall of water.  To accumulate the data and the observational knowledge to flesh out a “life history” takes good, down to earth (or ocean bottom), tedious, long-term, expensive and dedicated research.  Because of the effort involved, such work has been completed for precious few animals, most of which are temperate, due primarily to the prevalence of marine laboratories in temperate regions.

The Story

In this essay, I summarize the results of a series of research projects concerning a temperate octocoral, the sea pen, Ptilosarcus gurneyi.   This species has also been known as Ptilosarcus quadrangulare,  Leioptilus quadrangulare, Leioptilus guerneyi, and  Ptilosarcus quadrangularis, but these names have long been considered to be junior synonyms.  Nonetheless, they still turn up from time to time, particularly in comments on the internet.  The basic research on which this article is based was reported in two papers (Chia and Crawford, 1973; Birkeland, 1974), but in addition, there is a significant amount of my own hitherto unpublished research.  For ease of readability, I will not cite either main reference again.  If the reader is interested in more detail, please read these articles or contact me directly.  In total, this information represents several thousand person-hours of observational time.  As far as I know, no similar body of knowledge exists for any tropical octocoral, although there are similar accumulations of information regarding some Mediterranean gorgonians.  I hope, however, that this example will give some appreciation for the life history of, at least, one type of octocoral.  Perhaps, as well, this essay will present the types of data needed to discuss the biology of these animals.

Figure 1.  A mature Ptilosarcus gurneyi individual extended about 50 cm out of the sediment.  The primary polyp consists of the base which extends into the sediment, and the rachis or stalk extending from the base up between the “leaves.”  The gastrozooids or feeding polyps are found on the outside of the leaf edges, while the siphonozooids, or pumping individuals, are found in the orange regions on the sides of the rachis.  The “warts” on a few of the leaves are caused by a parasitic isopod living inside the pen’s tissues.

 

Figure 2.  A portion of a sea pen bed in the central Puget Sound region, the depth was about 15 m.  Water flow was from the left, and the foreground field of view is about 1.5 meters (5 feet) across.

Sea pens are octocorals.  Taxonomically, they are placed in the Order Pennatulacea of the Subclass Octocorallia (= Alcyonaria), in the Class Anthozoa of the Phylum Cnidaria.  All of this jargon means they are animals whose major body parts consist of modified polyps.  Being octocorallians, their polyps show an octamerous or eight-fold symmetry most obviously manifested by the presence of eight tentacles around the mouth of the feeding polyps, or gastrozooids.  These eight tentacles each have a series of small side branches, a condition referred to as “pinnate branching.”  Unlike other octocorals, sea pens are mobile.  While they are sessile, living in unconsolidated ocean bottom sediments, they are not fastened to the substrate and at least some sea pens are capable of significant locomotion.  

The adult sea pen is body considered to be comprised by the fused modifications of three types of polyps.  The base and central stalk region, or rachis, is considered to be the modified original polyp.  The feeding polyps possess tentacles are called gastrozooids and typically found either extending from the surface of the rachis much like the spokes of an umbrella, or on lateral extensions from the rachis, the “leaves”.  Depending on the sea pen species and the adult size, there may be from about ten to many thousand gastrozooids.  Embedded in the rachis surface are the siphonozooids; modified polyps lacking tentacles.  These structures consist of a “mouth” which is lined with microscopically sized, beating, hair-like projections called “cilia.”  Siphonozooids pump water into the body of the colony.  The colony has quite an intricate system of channels which allow the movement of water and nutrients throughout the body.  The forces necessary for the water movement comes from muscular contraction of the body and the beating of the cilia lining the water channels.

 

Figure 3.  The “leaf” edges of a mature sea pen showing many gastrozooids.  The leaves are oriented into the current, and can generate hydrodynamic lift.  When the animals are disturbed, they may orient into the current, inflate, climb out of the sediment, and drift away in the current.

 Figure 4.  The siphonozooid region of a sea pen rachis; siphonozooids, basically polyps without tentacles, pump water into the pen.  Small stenothoid amphipods are commonly found on the pen’s surface. 

Sea pens are like the late comic, Rodney Dangerfield, in that they “don’t get no respect.”  They are often largely ignored in invertebrate zoology classes, and hardly discussed at all in many marine biology classes.  Nonetheless, they are surprisingly abundant and, in fact, may be the dominant cnidarians over large regions of the earth’s surface; areas where stony corals, other octocorals, and most sea anemones are essentially absent, the deep sea soft-sediment bottom.  The largest of Earth’s ecosystems, much of this area is characterized by the presence of sea pens.  I doubt anybody has made the calculations, but I suspect that it would a sure bet to say that the biomass of sea pen living tissue exceeds that of all other benthic cnidarians combined. 

Figure 5.  A small sea pen that had been drifting across the bottom.

Ptilosarcus guneyi, the subject of this article is found throughout the Northeastern Pacific from Alaska to Southern California.  Fully expanded, large, adult individuals may extend for about 60 cm (2 feet) out of the sediments, with the base extending into the sediments another 15 to 30 cm (6 to 12 inches).  Fully contracted, these same large adults will be about 15 to 20 cm (6 to 8 inches) long.  The body color ranges from a pale cream to deep orange red.  The body morphology may remind one of a fat, carrot-colored quill pen; hence, “sea pens”; alternatively, when contracted, they may remind one more, simply, of carrots.  Internally, they contain a single large calcareous and proteinaceous style.  The size of the style is related to the age of the sea pens, and measurements of it may be used to obtain ages of individuals in a population.  Ptilosarcus gurneyi are found in shallow waters, ranging from the lowest intertidal zone to depths of about 500 feet, but are most abundant in shallow waters.  And, the animals in this species may be amazingly abundant.  In the Puget Sound areas studied by Birkland, the number of sea pens averaged about 23 pens per square meter, with about 8 of these being three or more years in age.  Sea pen beds typically reach depths in excess of 50 m, and extend laterally for dozens of kilometers, interrupted only physical features such as scouring by river currents, dredged harbors and the like.  Although these beds are discontinuous, because of the currents in the area, they are not isolated from adjacent beds.  Larvae are dispersed throughout the region, and even adult pens may move laterally great distances.  The adults can crawl up out of the sediment, inflate with water, and drift along in the currents, much like an underwater balloon.   

Figure 6.  A sea pen photographed in the field, shortly after the spring equinox, a day or two prior to spawning, showing the eggs in the gastrozooids.  The extended nature of the gastrozooids is visible in the image.  Their guts extend through the leaves into the rachis where they meet and fuse with a large internal canal system that extends throughout the animal.  The eggs are about 0.6 mm in diameter.

The sea pens have a cyclic behavior pattern of inflation, feeding, and then deflation.  They may do this several times a day, and the rhythm appears more-or-less unrelated to feeding or available foods.  At any one time, Birkeland found that only about a fourth of the pens were exposed, with the rest being completely buried in the sediments, often to a depth of 30 cm (1 foot) or more.  The sea pens totally dominate and structure these communities.  Very few other macroscopic animals live in the sediments of sea pen beds, possibly because the continuous bioturbation resulting from the movement of the sea pens.    

As one might expect, the shear mass of sea pen flesh in these areas is a resource that has not “gone unnoticed” by predators.  In fact, there is an amazing variety of predators that have become adapted and, in some cases, totally dependent upon the sea pen populations.  In many respects, Ptilosarcus gurneyi in sea pen beds fills an ecological position similar to the huge herds of bison that used to occupy the American Great Plains or the grazing animals of the Serengeti.  In each of these cases, whole food webs were built upon the basic primary resource species.  Sea pens are suspension-feeders eating small organic particulate material, larvae, and other small zooplankton.  In turn, they are the food of a wide variety of benthic predators.  When small, they are eaten by several, mostly small, nudibranch species.  As they grow they become too large for some of the nudibranchs, although others may still eat them.  However, as the pens grow to maturity, they become the prey of several sea star species.  At the apex of this food web is yet another sea star, which preys on those stars.

In The Water

Ptilosarcus gurneyi generally spawns in the first week following the spring equinox.  In the laboratory during that time, sunlight hitting a tank of gravid sea pens that has been shaded will induce spawning.  The eggs are large, about 600 μm across, and a mature female colony will produce upwards of 200,000 of them.  Fertilization occurs in water column.  Embryonic development occurs over about 3 days at 12º C, and results in a foot-ball shaped, mobile, non-feeding, planula larva about 1 mm long.  After about five days, planulae raised in the laboratory begin to swim to the bottom of their containers.  By inference, the same behavior in nature would move them toward the ocean bottom.  In laboratory containers, they repeatedly swim vertically downward and touch their anterior end to the sediments.  If the sediments are coarse sand, with particle diameters in the 0.250 to 0.500 μm range, they will stick to, and “settle” into that sediment and begin to metamorphose into a small sea pen.  If appropriate sediments are not available, settlement and metamorphosis may be delayed for as much as a month.  Without appropriate sediment, the animal will die.  These pens are found in an areas dominated by vigorous tidal flows and offshore currents.  In a month, the larvae could disperse over great distances. 

  

Figure 7.  Drawings done from life of developing Ptilosarcus  gurneyi embryos.  Top.  The newly released ovum.  Center.  Embryo at about the beginning of the 4-cell stage; about 4 hours old.  Cleavage is incomplete and doesn’t extend through the embryo.  Bottom:  Embryo between the 4 and 8 cell stages, about 6 hours after fertilization.

 

 Figure 8.  Drawings done from life of developing Ptilosarcus  gurneyi.  Top.  The 8-celled stage is about the same diameter as a newly spawned egg; about 7 hours after fertilization.  Center.  The embryo is at the 16-celled stage; about 8 hours old.  Bottom:  This embryo is at the blastula stage, about 12 hours old.

   

Figure 9.  Drawings done from life of developing Ptilosarcus  gurneyi.  Gastrula stages; individual cells no longer visible.  Left.  Early gastrula, irregularly shaped, about 24 hours old.  Center.  Gastrula, about 36 hours old.  Right:  Late Gastrula, the embryo has become ciliated and is swimming; 2 days old.


 
 

 Figure 10.  Drawings done from life of developing Ptilosarcus  gurneyi.  Top.  Early planula, about 3 days old.  Bottom:  Planula larva at 4 days old.

 

Figure 11.  Drawings, done from life, of developing Ptilosarcus  gurneyi.  Top.  Planula at 5 days.  Center.  Planula, settling, about 6 days.  Bottom:  Settled larva undergoing metamorphosis into a juvenile sea pen; about 8 days of age.  The animal is capable of contraction and elongation.

Once metamorphosis begins development to a feeding individual is rapid, with the first polyp having functional tentacles within 2 weeks of spawning.  Active feeding begins soon thereafter and given sufficient food, growth is relatively rapid.  Once the sea pens have settled, they become potential prey for many predators.  Birkeland found that small sea pens are eaten at the rate of about 200 per year per square meter by small nudibranchs.  If they can survive this period, they get large enough to avoid becoming prey for the smallest of the nudibranchs, but they graduate into become food for sea stars.  Sea pens grow at a relatively constant rate, reaching sexual maturity when they are about 24 cm (9. 4 inches) tall and five years old. 

Both growth and predation rates are continuous; there is no cessation of growth upon reaching an “adult size.”  As with many cnidarians, no old age or senescence is demonstrable in these animals.  Nonetheless, they don’t live forever.  In essence, Ptilosarcus life is an exercise in “beating the odds,” and as in all such cases, the “odds,” – in this case, the odds of being eaten by a predator – are too great for indefinite success.  The life expectancy of an individual sea pen in the Puget Sound areas appears to be about 14 to 15 years.  Older animals may be occasionally found but, if so, they are very rare. Predators aren’t the only source of mortality in sea pens, nor are sea pens immune from parasites which may influence their growth and survival; however, these factors remain unstudied.

 

 

Figure 12.  Drawings, done from life, of developing Ptilosarcus  gurneyi.  Larva undergoing metamorphosis.  Top.  11 days.  Center.  13 days old; tentacles clearly evident; bumps on body surface are of unknown function, spicules were not present; mouth is open and a gullet or gut is evident.  Botom:  15 days old; note the development of the first pinnae on the tentacles.

 

 

 Figure 13.  Drawings, done from life, of developing Ptilosarcus  gurneyi.  Two individuals about 3 weeks old; spicules are visible in the body wall.  They have one complete feeding polyp, the primary polyp, and siphonozooids on the stalk.  The animals were actively feeding at this time and were about 3.5 mm long.  The extent of the visible gut is shown in the right individual.  The individuals were settled and growing in coarse sand.  At this point, I terminated this growth series and transplanted the juveniles to a sea pen bed in one of my benthic research study sites.  

 

Figure 14.  A juvenile sea pen, photographed in nature; depth about 15 m.  The animal is an estimated one year old.  It was between one and two centimeters (about 0.4 to 0.8 inches) high.  Note gastrozooids, and the internal calcareous style (visible as a white band).

 

 

Figure 15.  Juvenile sea pen, photographed in nature; depth about 15 m.  This animal is about two years old.  It was about 5 centimeters (about 2 inches) high.  Note: the gastrozooids, the siphonozooids (visible as bumps on the stalk), and the developing leaves.

 

 Figure 16.  Older juvenile sea pen, probably about 4 years old, about 15 cm (6 inches) high.  The internal style that can be used to age the animals is clearly visible as a white internal stripe.

 

Figure 17.  Evidence of incomplete, or attempted, predation; in both cases these partially eaten sea pens probably were attacked by nudibranchs.

   

 Figure 18.  The Predators.  These nudibranchs primarily eat the smallest pens and become common in sea pen beds shortly after the juveniles settle and metamorphose out of the plankton.  Top. Hermissenda crassicornis.  Bottom.  Flabellina trophina.  Both nudibranchs are small, reaching lengths that do not exceed about 4 cm (1.6 inches).  These species are responsible for the deaths, on the average, of upwards of 200 sea pens per square meter, per year.

 

Figure 19.  The Predators.  This nudibranch, Tritonia festiva, reaches lengths of about 10 cm (4 inches) and primarily eats small to medium-sized sea pens, but will not hesitate to take a chunk out of a larger one, as the above individual is about to do. 

  

Figure 20.  The Predators.  These two large nudibranchs, Tritonia diomedia (top) reaching lengths of 15 cm (6 inches) and Tokuina tetraquetra (bottom) reaching lengths in excess of 30 cm (12 inches) also eat sea pens.  Tritonia is common in sea pen beds, Tokuina are uncommon in those areas, and tends to eat isolated sea pens growing in sediment pockets in rocks.  Individuals of these two species can eat the largest of sea pens without any difficulty whatsoever.

 

 Figure 21.  The Predators.  These images show Armina californica, (top) probably the most abundant nudibranch predator that eats Ptilosarcus in the Puget Sound region.  Although solitary individuals are capable of eating a pen, these animals are gregarious and are often seen clustered over the remains of their prey (bottom).  Armina californica are reach lengths of about 10 cm (4 inches) long, and will eat all size categories of pens.

Figure 22.  The Predators.  In the areas of the sea pen beds, about 50% of the food items eaten by the rosy sunstar, Crossaster papposus, are sea pens.

 Figure 23.  The predators.  In the areas of the sea pen beds, about 98% of the food items eaten by leather star, Dermasterias imbricata are sea pens.

Figure 24.  The Predators.  The vermillion seastar, Mediaster aequalis,  preys on sea pens, among many other things.  Here a sea star is hanging on to a previously buried sea pen that is expanding and trying to dislodge it.  Pens bury into the sediments and, if stimulated, the pen will sometimes inflate, and expand in an apparent attempt dislodge the predator.  Note that the pen has lifted the sea star totally off the substrate.

 

 Figure 25.  The Predators.  The spiny sea star,  Hippasteria spinosa, eats only sea pens.  It takes a full grown star about 4 to 5 days eaten a fully grown sea pen.

 Figure 26.  The end result of the effects of all of the predators is the style.

 Figure 27.  The Green Disease.  As if predation wasn’t enough, the sea pens are subject to other maladies.  The green coloration in the pens above is caused by an endoparasitic green alga, which appears to kill the pens, albeit it takes several years to do so.

Figure 28.  Not all Ptilsosarcus gurneyi in the Northeastern Pacific are found in dense beds.  They may be found in many other habitats where sand pockets of the appropriate type occur.  The anemones to the left are Urticina piscivora, and are about 30 cm (12 inches) across the oral disk. 

During their lifetime, these pens probably reproduce about ten times.  If the average number of eggs produced by one pen is 200,000, then each female will produce about 2,000,000 eggs over her life span.  If the populations are assumed to be constant, neither shrinking nor growing, then over the life span of the female she must spawn the eggs to replace herself and her mate, indicating the odds of survival to successful reproduction by any given Ptilosarcus gurneyi individual in the Puget Sound region is about 1,000,000 to 1.  Although those odds seem pretty slim, they are significantly greater than many other marine animals such as pelagic fishes.

  Figure 29.  Juvenile Ptilosarcus settle in dense assemblages; they have to, to be able to withstand the predation pressure of the array of predators that feed upon them.

 Finishing Thoughts…

 There are some things that may be taken to heart from my tale of sea pen life and, mostly, death.  First, despite their apparent simplicity, these are hardy animals capable of surviving much environmental perturbation and unless they are eaten, they have the potential of living a long time.  Second, they are mobile and capable of movement, and will leave areas that are not to their liking.   Third, although P. gurneyi  lack zooxanthellae, they have a rapid growth rate.  The Puget Sound region, the so-called “Emerald Sea,” is exceedingly rich in plankton.  One reason sea pens are so abundant in the region is all of the potential food.  They eat small zooplankton.  They probably will not eat much phytoplankton unless it is a suspension of clumped cells.  Finally, these are very neat and strikingly beautiful animals, I haven’t even touched on their bioluminescence, but suffice it to say, in a dense sea pen bed at night the blue green glow from the pens is bright enough to take notes by.   This species is as typical of the Pacific Northwest as apples and sasquatch, and yet it is almost as unknown as the giant Palouse earthworm.   And that is a pity! 

References:

Birkeland, C. 1974.  Interactions between a sea pen and seven of its predators.  Ecological Monographs. 44: 211-232.

Chia, F. S. and B. J. Crawford. 1973.  Some observations on gametogenesis, larval development and substratum selection of the sea pen Ptilosarcus gurneyi. Marine Biology. 23: 73-82.

Kozloff, E. N.  1990.  Invertebrates. SaundersCollege Publishing. Philadelphia. 866 pp.

Ruppert, E. E, R. S. Fox, and R. D. Barnes. 2003. Invertebrate Zoology, A Functional Evolutionary Approach. 7th Ed.   Brooks/Cole-Thomson Learning. Belmont, CA. xvii +963 pp.+ I1-I 26pp.

Shimek, R. L. Unpublished Observations.

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Predators In The Sand, Or…

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

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.  

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. 

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

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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Gastropteron

August 8th, 2011

Although they look like they are nudibranchs, the two snail species featured in today’s posting are surely not nudibranchs, even if one is kind of sluggish in form and fashion.  The larger of the two, Gastropteron pacificum, is a bubble shell, meaning it has a shell that looks quite like a soap bubble and it is about as durable.  When sitting on the bottom, the animal is about the size of a grape.  The sides of the animal’s foot are expanded into two long lateral lobes that are normally folded up over the animal, but virtually nothing of the animal is normally visible as it is generally covered in a mucous sheet which, in turn, is covered by sediment particles.  The animal looks like a lump of mud on a bottom that is covered in lumps of mud, and so this is pretty good camouflage.  

Gastropteron pacificum, a stationary lump of pseudo-mud. The pink structure is a fleshy, tubular, siphon that brings in breathing water. 

Gastopteron pacificum individuals are found frequently in the spring in waters of the North American “Pacific Northwest” and if a diver ventures into its gorpy, mucky, muddy habitat – otherwise known when I was working in these areas, as a “Shimek study site” –  one can often see the trails left by these little guys as they move around, presumably in search of food or a mate. 

Gastropteron pacificum, leaving a trail in the mud as it crawls from there to here.

They are probably detritivores, as they are reported to eat detritus and diatoms in the laboratory, but I am not sure what they eat in nature, and neither, to the best of my knowledge, is anybody else.  I don’t think they have been studied in any detail which, if true, is quite a pity as they are neat little critters.  When something startles them – a diver (me) in my case for the photograph, or the presence of a bottom-feeding fish, such as the ratfish, Hydrolagus colliei, the little snail unfolds its foot flaps and flaps away.  They are quite strong swimmers and this appears to often be an effective escape response.  

Hydrolagus colliei

This ”rat fish,” or ”chimerid,” is a cartilaginous-skeletoned fish but obviously not a shark.  Individuals in this particular species can reach about 70 cm (28 inches) in length. Rat fishes are some of the most common predators in the soft-sediment ecosystems of the NE Pacific, and some of my unpublished data indicate they feed on mollusks, annelids, and echinoderms. 

A Gastropteron pacificum individual.

This little animal is swimming away from the most fearsome and horrific predator of all, a diver – in this case, of course, me.  I was sensed, probably by my water disturbances, and it then took off, and stayed waterborne for about 2 minutes.  Although Gastropteron swimming appears to be undirected, given the currents in the region, it will likely cover some distance before it quits swimming and falls back to the bottom.

If the Gastropteron is successful in its life, it find a good friend and they will do the snaily version of the ”wild thing” resulting some time later in the deposition of some jelly-like ”egg masses” attached to the bottom.  These are filled with small fertilized eggs (zygotes) that develop within the misnamed egg mass, which eventually dissolves releasing the larvae into the plankton. 

A group of Gastropteron “egg,” actually embryo, masses. I don’t know if all of these are deposited by one individual or if they aggregate during spawning to deposit the jelly-like masses (many snails in this region do form spawning aggregatations).

However, they don’t get a break!  There is a small sacoglossan slug, Olea hansinensis, in the area that searches out and eats the eggs of Gastropteron and its relatives.    

Olea hansinensis.

This is a small sacoglossan slug that eats eggs of cephalaspidean snails, such as Gastropteron.  This one was about 3 mm (1/8th inch) long, but larger individuals are said to reach about 13 mm, or half an inch in length.

More later,

Until then,

Cheers,

 

 

 

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Starting Something New

July 19th, 2011

Nudibranchs

For quite a while I have wanted to post a number of my underwater images which were taken from 1975 through 1994, mostly in a few of the shallow water environs of the Pacific Northwest, a.k.a. the Northeastern Pacific.  Most of these were taken to be illustrative, that is to show the animal or organism, primarily for lectures or in presentations, they were not meant to “artsy” images, although some certainly turned out that way.  I finally have bitten the bullet, and am scanning a lot of these images into high-definition digital form, this being largely facilitated by the purchase of an external hard disk drive (HDD) of terabyte capacity, so that I actually have a convenient place to store the images.  Judging from the size of the scanned images, I may well fill that HDD.  However, I obviously can’t post such high definition images here, nor can I post them all, as I estimate I have well over 5,000 images.  Consequently, I have decided to post a few every few days for the foreseeable future. 

Unfortunately, the posted images are really not the best quality; the images scanned from my slides average about 80 Mbytes each, so, the images posted here are really quite low in resolution.  Sorry about that, but it can’t be helped.  In my scanning, the order is not random, but it is also not taxonomic.  It is “slide holder order.”  I had/have arranged my opisthobranch slides in slide holders in a loose leaf notebook with the nudibranchs first, but within that group they are in more-or-less haphazard order.  If that bothers you, exit now and save yourself the heartburn.  Once I get them all scanned, I will arrange them in some sort of logical order, but that is in the future.  

The very diverse and species-rich array of animals grouped under the name ”Opisthobranchia” were, until recently, thought to be related.  That is no longer the case, and while some subgroupings within the old group, such as the nudibranchs, are good taxonomic groups, the term “opisthobranchia” is now obsolete and used only as an informal term, and one I suspect will die out over the next few decades.  I hope you enjoy the images and the commentary that goes with some of them.  The taxonomic nomenclature (i. e. the names) used in the opisthobranch image postings follows that given in the fine photo reference book:  Beherens, D. W. and A. Hermosillo. 2005. Eastern Pacific Nudibranchs. A Guide to the Opisthobranchs from Alaska to Central America. Sea Challengers Publications. Monterey, California. vi + 137 pp.  If I have made any mistakes in the listing or image names, those are mine and mine alone.

Hermissenda

Hermissenda crassicornis, the opalescent nudibranch.  Photographed at a depth of about 10 m on the 4th of July, 1992 in Barkley Sound, Vancouver Island, British Columbia, Canada.

A pair of Hermissenda crassicornis, the opalescent nudibranchs.  These were photographed at about 10 m on the 14th of October, 1983 near Ohiat Isand in Barkley Sound, Vancouver Island, British Columbia, Canada.

These nudibranchs are not social animals and their appearance together is probably happenstance.  However, they may be getting together to mate.  Unlike many other nudibranchs, particularly the dorid nudibranchs in which copulation may take many hours, mating in Hermissenda is anything but sluggish.  As with all nudibranchs, they are hermaphroditic and mating is reciprocal.  From start to completion, copulation takes but a small fraction of a second.  

A Hermissenda crassicornis, the opalescent nudibranch.  Photographed at about 12m depth, on the 2nd of June, 1982 in Barkley Sound, Vancouver Island, British Columbia, Canada.

The above opalescent nudibranch appears to be on a rock with brown algal filaments on its surface, but that is misleading.  The scene is one of a small patch reef created by the annelid worm, Dodecacaeria fewkesi.  What appears to be brown algal filaments on the substrate are actually masses of tentacles arising from the worms whose calcareous tubes are cemented together forming the reef. 

And there is more going on!!!

The tall structures in the background are hydroid colonies; probably the nudibranch would be eating the hydroids if it were on them.  The small white blobs on the hydroids are either individuals of another nudibranch, from the genus Doto, or that species’ eggs.  During the spring, everything in this region grows like crazy, particularly those animals, such as the hydroids, that feed on plankton, which is very abundant.  In this case, the hydroids, of course, feed on small zooplankton. Individuals of Doto species feed on the hydroid polyps and their populations bloom right after they hydroids have their growth spurt.  These small nudibranchs, about 3 or 4 mm long, can have population densities exceeding 5,000 per square meter, and will be featured in an upcoming post.

Dodecaceria fewkesi, the “reef building” cirratulid worms.  Photographed on the 28th of April, 1984 inDodger Channel, Barkley Sound, Vancouver Island, British Columbia, Canada.

These worms secrete the calcareous tubes that they live in.  Dodecaceria individuals aggregate together, probably due to asexual reproduction as well as larval recruitment.  In doing so, their calcaeous tubes fuse forming, first, what appear to be small rocks with worm holes in them.  Later, as time goes on, these rocks grow by the addition of more worms.  In doing so, they create one of the few types of reefs, other than those made by corals, that are biogenic, or made by living organisms.  These worm reefs are never very large, but they can be as much at 20 to 30 (6 to 9 m) feet long and 6 to 10 feet (2 to 3m) high, or as big as some coral patch reefs.

A portion of a small reef built byDodecaceria fewkesi, the calcareous-tubed hair worm.  Photographed on the 29th of April, 1983 in Pole Pass, between Crane Island and Orcas Island, in northern Puget Sound, Washington, USA.  The slightly “foggy” appearance to this image is due to small plankton in the water reflecting my strobes’ light. 

This image shows the small “rocky reef” made by the hair worms.  This area in the San Juan Islands of Washington, was one of my primary research study sites in the early 1980s.  In addition to the small patch reefs made by this worm species, there are other, much larger, reefs at this site that are made by a different type of worm, the sabellariids, and I will probably post images of them in the future.  Most biologists don’t realize that corals are not the only reef forming animals, and when told of these worm-built reefs, often respond with disbelief and incredulity.  Nonetheless, such structures are reasonably well-known and described in the scientific literature. 

As with coral reefs, these worm reefs are “hot spots” of local species diversity.  However, there small size and lack of much 3-D heterogeneity, limits the number of other animals that live with them.  Nonetheless, opalescent nudibranchs, and the hydroids they feed on are often common on these reefs.   Due to the distance from the reef, not much other life is recognizable in this image, though.  The large white blob is probably a contracted plumose sea anemone (Metridium sp.), which when inflated fully would be a couple of feet high.  The golden crescent near the bottom, is the aperture of a large scallop (Hinnites sp.) that is found in the area.  These animals cement their shells to rocks, and unlike most scallops are immobile when they are adult.  That individual is probably about four inches (10 cm) across.  

Flabellina

 There are lot of small aeolid nudibranchs found on, and eating, hydroid colonies or other cnidarians in the spring in this region.  Here are a couple of shots relating to, and of, Flabellina trilineata.

The orange structure is a colonial hydroid, Garveia annulata, that was occasionally common in some areas that I dove in.  The hydroid colony in this image is a couple of centimeters long. Notice the large orange “balls”  (reproductive polyps), they are about 1/4 mm in diameter.

The three-lined nudibranch, Fabellina trilineata.  This little nudi reaches lengths of about 1.5 inches (36 mm) or so, and is commonly found in the spring in rocky areas in the Pacific NW subtidal regions.  It,  like many aeolid nudibranchs eats hydroids, including Garveia.

This image shows a baby F. trilineata (notice the rows of tiny cerata growing on its back) eating Garveia.  The nudi is about 2 to 3 mm (about 1/8th inch) long.  You can get an idea of size by noting the reproductive polyps and comparing this image with the images of Garveia, above.

One of the activities I tried to do at times during my diving career was to take “extreme” macro shots of various invertebrates in the field.  I had an apparatus that allowed me to get an image magnified up to about 12x on the slide; so, if the animal was 2 mm long, the image would be about an inch long on a 35 mm slide.  In this case, the nudibranch in the last image above was magnified about 8 times.  There were a lot of technical problems with taking these images, not the least of which was that the object to lens distance was very small, and that it had to be accommodated within my camera’s underwater housing.  Given the water currents in the areas where these images were taken, even holding one’s position during the water flow, euphemistically referred to as slack water, could be difficult.  The large camera and strobe housing caused an immense amount of drag, and severely limited my mobility.  Other problems included looking through the viewfinder of the camera with a scuba mask on, and so on…  Suffice it to say getting any sort of image was a problem.

The major difficulty, however, was getting enough light hitting the very small object to reflect back, passing through the underwater housing plastic, then the lens, and then the bellows that was on the front of the camera, and into the camera to properly expose the film.  I began to feel like I needed a tactical nuke to take the picture.  If I was able to successfully expose the object so that the slide was properly exposed, it sometimes felt like I need to produce so much light that it would vaporize the object I was taking photographing.

In the above image of the baby Flabellina on Garveia, the digital software ”pushed” the exposure quite a lot, but doing so increased noise, and that noise is particularly apparent at the low resolution I must use here.  That is why the image is a bit blurred.  It can’t be helpped, sorry.

The next species of choice is Flabellina trophina, one of the more blah of the these normally spectacular wee beasties.  Nonetheless, I have a fair number of images of it, as the species was common in some habitats I was investigating, and there were often not a lot of other animals visible there, so rather than return to shore with only half a roll of film shot off, I would take images of individuals of this species of nudi, and sometimes a few other critters.

Flabellina trophina.  Photographed near Seattle in central Puget Sound, WA. in 10 m of water in 1982.

A head-on view, this image shows to advantage the extensions of the brown or tan digestive gland up into the cerata on the animal’s dorsum.  “Cnidosacs,” specialized structures containing undischarged nematocysts from the animal’s previous dinners are located at the tips of each ceras and their presence is emphasized by the bright white coloration.  This is probably aposematic or “warning” coloration for any visual predator, in these cases either a fish or crab that might consider this nudi a tasty snack.

Flabellina trophina.  Photographed near Seward, AK in 10 m of water, in 1982.

This shows the animal in a side or lateral view; F. trophina can reach lengths of about 50 mm, or 2 inches.  The structure visible on the animal’s right shoulder is the combined anal and genital apertures.  All nudibranchs have their genital openings in this region, but the anus may vary in position, and that is – as one might guess – one of the characteristics defining each different subgrouping within the nudibranchs.  The aeolidacea all have these apertures in position as shown in this individual. 

Flabellina trophina.  Photographed south of Seattle in central Puget Sound, WA. in 12 m of water in 1988.

I have no quantitative data, but my notes list several observations of this species feeding on sea pens (Ptilosarcus gurneyi).  I was working on photodocumenting the events occurring in sea pen aggregations (called sea pen “beds,” for no logical reason known to human cogitation).  Over some 20 plus years, I made, maybe, 150 dives in this habitat and took several hundred images. There will be slides of many other different animals posted during these excursions through my slides that were taken in the sea pen aggregations.  Starting with some nice research by Chuck Birkeland the natural history and “ecology” of the sea pens in the Puget Sound region are probably the most well known of all pennatulaceans.  In any case, I was photographing F. trophina in the beds not because it was documented to feed on the sea pens (it was not, even though I found that it is a common predator on them – or at least it was when I was actively diving in those areas), but rather because it was common and somewhat attractive, and sometimes, I just wanted to take its picture. :-) .  I took the above image because it shows a lateral view of the animal with its snout elevated which is a common posture.

Flabellina trophina.  Same images as above. 

While I was preparing the scanned image for this post to the forum, which involved making lower (much lower) resolution images, I noticed what I thought might be artifacts due to fine hairs that got on the slide prior to it being scanned.  And, gee, living in a house with a large hair factory, one that specializes in producing very thin, fine hairs (a.k.a. – my true buddy, Casper = “A Maine Coon Cat” = giant fur ball).  I figured that if these were, indeed, fine Casper hairs, I would have to reclean the slides and try scanning them again.   The “hair” images/artifacts are circled, and if one examines the image above this one, it is quite possible to see them without the circles.  There are a lot more faint “hair-artifacts” visible than are circled.  

My buddy, Casper, a generator of loose, fine hair, but not guilty of being the source of “hair-like” images on my nudibranch slides. 

Flabellina trophina.  Same images as above. 

When I examined the fine “hairs,” I found that Casper was off the hook, they were not artifacts at all, but were actually part of the original image.  They were microscopic phytoplankton floating by in the water as I took the images.  As I described above, I could photograph microscopic subjects.  Well, here is the inadvertent proof of that statement!  And, it is something that I had never seen on the image before this scan! 

I further enlarged the portions of the images in the red circles and included them in the original image.  They are shown outlined in red and are indicated by the arrows.  Note the “zig-zag” structures.  Well, those structures are not 2-D zig-zags, but rather 3-D helices of chained diatoms.  Here is a link to a photomicrograph showing similar diatoms in a better view.  

WOW!!!  I think this is REALLY neat, because it shows how what appears to be the relatively clear water in a photograph of an underwater scene may, in fact, be filled with plankton that are just below the resolution capabilities of either the camera or the printer or scanner to show.  I have often heard a comment to the effect that a given tropical coral reef image shows water so clear that it is ”obvious” that there is no plankton in it.  I wonder how many of those images would show microscopic plankton of one sort or another if they had been taken with a better camera or printed in better manner.  

No plankton present…  LOL!!!  Obvious, INDEED!!!

More images soon.

Until then,

Cheers, Ron

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Wilsall, Montana

June 25th, 2011

As any of my regular readers, either here or on my forum know, I live in Wilsall, Montana.  Located in South-Central Montana, the scenery of the area around my home is striking.  If one can ignore the right-wingnut politics of rural Montana, which are rather like those of the communist-scare era of the early 1950s, but not as progressive, it can be a nice place to live.  However, because of the overabundance of nutcases, this is kind of  an odd place to be if one has any sort of decent liberal arts or science education; it keeps feeling like being transported to an alternate universe.  I keep wondering, “What is IT with these people?  The basic motto seems to be “On my honor to do my best to help myself and forget the rest.” 

I suspect the real problem is that many of the folks here haven’t had the dubious pleasure of living someplace else, so they don’t know how good they have it, and because of that it is easy for them to trash it by simple neglect and the inability to see that the government has a positive role to play in the process of maintaining the region’s well-being.  And -  shock of shocks!!! - that the taxpayers have a responsibility to fund it.  Not so for these dorks!   They want the ability to trash the place, and many of them are hell bent on doing so – and regretably they are succeeding. 

Fortunately, at the present time, at least, the process is still a relatively slow one.  With the increasing degradation caused by climate change, coupled with the inevitable population growth, the time will come soon enough when the children and grandchildren of the present folks will curse the lack of foresight of their progenitors.  And because, that time will mean the absolute loss through death and destruction of a lot that I hold dear about this place, I am glad I won’t be alive to see it.    

Oh well, for the present, here we are, and here we will stay.  Among things we simply can’t afford to move to anyplace else.    

The political and social environment aside, the area’s physical and biological environment is spectacularly beautiful.  Wilsall is in the Shields River Valley, which is bordered on the west by the Bridger Mountains and on the East by the Crazy Mountains.  The illustration below, courtesy of the remarkable software of Mr. Google et alia, shows the lay of the land pretty well.  The northern end of the valley is north of Ringling, Montana, where there is a watershed divide between the Shields River and the Smith River drainages.  The south end of the valley terminates in the  Yellowstone River valley, a few miles east of Livingston, Montana where the Shields merges with the Yellowstone.  I thought I would use the next few blog entries to showcase some of the spring and early summer scenery and wild (mostly birds) life found either in our yard in the small cowtown of Wilsall, or in the nearby region.  Some beautiful and interesting bird life is found in Wilsall, for at least the present.  And even though the changes for the worst are relatively slow, they are accelerating and are noticeable, so … that will not be too long, at all.

A Google map image showing the Shields Valley from south of where the Shields River empties into the Yellowstone River. Our house's location is shown by the small yellow marker. Wilsall is located at the east end of "Battle Ridge."

Sunset over the Crazy Mountains to the east of Wilsall, Montana. The highest peaks in this range are a skosh over 11,000 feet above sea level.

 

The Bridger Mountains to the west of Wilsall, as viewed from the Wilsall Reservoir a few miles north of town. As with the Crazy Mountains, the highest peaks top out at around 11,000 feet.

One of my favorite Wisallian birds - for that matter one of my favorite birds at all - is the Western Tanager.  Not only do they have spectacular coloration, they have neat behavior.  When I grew up in Great Falls, Montana, about 150 miles north of Wilsall, I had no idea such gorgeous creatures even existed, let alone could be commonly found at times within 100 miles of my home.  At the time of my youth, Great Falls was the city of small, brown sparrows.  It was home to a giant population of one of the curses of the North American avifauna, the damned English sparrow.   I pretty much thought that in a town, any town, about all one was likely to see were these small, nondescript or cursed ugly brown birds.   My dear wife disabused me of that stupid idea, and has shown me the absolute pleasure of looking at our little flying dinosaurs, for which I am truly grateful. 

With that background, you probably can imagine my wonder and delight at seeing my first Western Tanager here a few years ago!  I simply couldn’t believe my eyes.   Wow!!  I still can’t get over them.  NOR DO I WANT TO!!!  These lovies are here for a while in the beginning of summer.  This year we appeared to have 4 pairs which were here for about a month.  So for your viewing pleasure, in this post I have uploaded a few images of  some Western Tanager males.  Most folks know that there are some wonderfully descriptive names for the aggregations of some birds, probably the best known of these is, ”An Exultation of Larks.”  After watching the 12 pairs of Western Tanagers that were around our yard last year, we decided that a fitting descriptive name for a small aggregation of this wonderful species would have to be,  “A Squabble of Tanagers.”  What feisty birds!!!  And how absolutely wonderful to watch their interactive behavior!!!

A Western Tanager Male, in our silver poplar tree giving me an askance glance while I focused my camera on him from within my office about 20 feet from him.

A Western Tanager Male in our "fly-through" bird feeder located about 20 feet outside my office window. I think these males KNOW how good they look! This year we had a series of males ranging from ones with almost no orange/red on the head to ones that looked like their heads had been dipped in brilliant red/orange paint. There was quite a difference in aggressiveness - and even the most "laid back" Western Tanager males are AGGRESSIVE!!!

A Western Tanager male checking out some food. Unlike a lot of birds, these guys (and their gals) tend to closely examine some foods with one eye or the other before picking it up.

Well, that’s it for today!

More soon, there are some nice critters found around here.

Until later,

Cheers!!!

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Yes, I Am Still Alive…

June 1st, 2011

My wife went in for hip replacement (her seventh) surgery on 3 February, and I thought that after she returned home, I would have plenty of time to do her chores around the house, my chores around the house, and at least some of my regular work, including some regular updates to this blog.

Well, yes…  I am a total nutcase.

Now almost four months later, she is well on her road to recovery, and beginning to take back over her chores.  And I am slowly recovering from being a gibbering idiot at trying to do it all.  Maybe at one time I could have done this.  Not now, the decrepency (if that is a word) of old age has hit me with a vengence.

I had to prioritize – and blog writing was right down on the bottom. 

Howsoever, I have now given the two presentations I was scheduled to give, managed to hold body and soul together – and hold her body and soul together – keep the house reasonably clean, drive into town and do our shopping, and do my job on Marine Depot’s Forum, and frankly, I am pretty proud of myself.  Some things suffered.  I haven’t been able to keep up the yard as I should.  However, I have been feeding our birdies as I needed to.  And over this lousy, dreary, dim, awful, skummy, drizzly, spring;  in other words, an awful Montana spring thast was like a glorious Seattle winter – except we had more snow, that feeding of our avian dinosaurs has been necessary! 

Still and all, we made it! 

To any readers, if I have any, I hope to be writing regularly again within a couple of weeks.

Birdies

We feed a lot of birds, and have been doing so for a lot of years.  And boy, oh boy, has there been a difference in our returnees this year.   For those of you who don’t know, the small song birds are relatively long-lived, some of them well more than 15 years.  They also seem to return year after year to successful nesting grounds.  And that is what we try to give them.  We provide lots of good food, nesting areas where we can and as much as possible freedom from humankind’s favorite birders, cats.  Now don’t get me wrong, we don’t hate cats.  Quite to the contrary, my best buddy is my big Maine Coon Cat, Casper, and my wife’s darling is Lily, a feral kitten she rescued. 

However, cats do a real number on song birds.  And we can’t do much about adjoining yards, but we do pretty good at keeping our yard feline free, at least during the daylight hours. 

That, and lots of shrubbery and trees, and… wow… we normally have a LOT of birds.

But this year, while we have a lot of birds, the array is very different.  We love our blackbirds.  The arrival of red winged black birds in the first week of March is our sign that winter is waning.  And we love their chorus.  Their song is so wonderful – it truly lifts the spirit.  A few weeks after the red wings our grackles come back.  These are common grackles, no great shakes as birds go, you might say.  And you would be WRONG.  With their glorious irridescence and cocky attitude the male grackles are great guys to have around.  We know spring is here when we can say, “The gracks are back!!!!”

‘Cept this year, they almost weren’t. 

Last year we had about 15 returnees.   This year, only 3.  And the red-wing contingent was down tremendously as well, from probably about 20 to about 5.   You know if this drop is summed over much of the northern areas, these species have taken a tremendous hit over the winter.   In fact, a few more winters like the last one, and we will be out of the blackbird business.  And our world will be very much poorer.

Let’s hope that isn’t the case…

Until next time,

Cheers…

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Rossia

February 12th, 2011

One of my favorite animals is the little sepiolid squid found in the Pacific Northwest, Rossia pacifica.  So…

I thought I would just post a few images of this wonderful small squid.  The next two images were taken sequentially as rapidly as my strobes would recycle.   The color change occurring in response to the strobe’s flash was impressive and ”instantaneous.”

Rossia pacifica, in one of my research localities.

A Rossia that has changed color in response to my strobes. This is the same individual shown in the preceding image.

 The animal below saw me coming and watched me.  It moved a bit but not too much as I approached, presumably a predator, such as  a dog fish (Squalus) would try to catch a swimming squid, and .  When I got about a meter away, it turned “white;” at the ambient light at that depth it really just matched to bottom color.

A Rossia that "went white" when it saw me approaching. NOT a happy critter!

 Individuals of Rossia have a very stereotyped escape response.  It appears to be a response to slow patrolling predators on the bottom fauna, particularly dogfish sharks.  The sepiolid lauches from the bottom and swims about 30 to 40 cm above the bottom more-or-less in a straight line inking every few meters.  When it should ink the last time, it doesn’t, but it turns dark, throws its arms up in a “scatter” posture and drifts like an ink blot until it hits the bottom, whereupon it bleaches (which makes it effectively disappear) and rapidly covers itself with sediments.

Rossia in its "drifting" posture. This posture will occur prior to the animal dropping to the bottom and covering itself with sediment.

 

This is an ink blot made a swimming "escaping" Rossia. Unfortunately, the sediment in the water obscures it somewhat, but it mantains a coherent shape roughly that of a swimming squidlet.

Rossia drifting and mimicking an ink blot. It has already inked a couple of times, and is not actively swimming, but is just drifting in the current.

After the successful escapes, eventually eggs are laid and after several months they hatch.  The first image is of an egg clutch.  The next two are of a newly-hatched, itsy-bitsy, baby Rossia. 

 

Rossia pacifica egg capsules on an old discarded coffee mug. The capsules are about a centimeter long.

A newly-hatched Rossia. Less than a 1 cm long, this animal is probably only a few days post hatching..

A baby Rossia swimming. When this color pattern occurs as the animal is swimming, it effectively "disappears" and becomes very cryptic as it swims or drifts over the substrate.

This last image is of a Rossia watching me as I took its picture.  Who could resist those eyes? 

A Rossia watching me; it was about 2.5 centimeters (1 inch) long.

Until next time,
Cheers,

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Identifications…

January 11th, 2011
Ah… well, yesterday I started to do some research on an article which may have the title of  ” The Vampires of the Sea.”  A twilight  article dealing with…

those bloodsuckers, bar none – Pyramidellid snails.   

Whether or not I develop this article fully depends on a lot of things, not the least of which the direction my muse (and I do have one – a characteristic I find “amusing”…  :-) ), takes me.  And also, of course, whether or not, I can find an editor who will accept it.  Anyway I am still in the very early stages of this thing, and I am trying to find some more background information about Pyrams. 

Now, like Yogi, I figure I am a bit “better than the average bear” with my knowledge of the group, but I really need to know more before I do anything that can be considered to be a reasonable and – hopefully – entertaining article about them.

Basically, the Gastropod family Pyramidellidae is a very large group of small… white… snails without any really nice identifying characteristics.  There are, quite literally, thousands of names applied to these snails, and how those names relate to the actual species – if any – of those snails is really open to question.  As with many marine groups – probably as with MOST marine groups – of animals, they are a taxonomic mess.  There are three basic reasons for this, the primary one is that they are all – dare I say it, again – small,  white, and feature-less snails.  If you think about it, once you have the basic constraints of a small, helically-coiled, shell, there are NOT a lot of ways that those constraints can be varied.   In point of fact, back in the 1960s, a paleontologist named David Raup, wrote a series of nice papers noting that virtually all marine animals with a “shell” can be easily described mathematically (Raup, 1962; 1966; 1969). 

The term “shell” in this sense is restrictive and excludes arthropods – even though they are “shellfish” they don’t have a “shell” in the way that Raup meant: “a non-living external covering to the animal.”  What arthropods have is an “integument” – a covering that is made of an intricate and complex fusion of living and secreted elements that is an integral part of the animal’s body, interiorally and exteriorly.  If you try to remove a shrimp’s “shell,” you are left with a mass of dead flesh.  If you try to remove a snail’s or a clam’s shell, you will find that, in many cases, it is quite possible to do this and still have a living animal.  And that animal may remain alive – in the case of some snails – indefinitely.  Clams without a shell perish in short order, as they can’t feed.  But snails without a shell can generally do everything shelled animals can do.   Everything, that is, except withstand the bite of a predator’s jaws.  Virtually every biologist who studies large populations of marine snails occasionally finds a shell-less one; probably an animal whose shell was eroded away by a sponge, or whose shell was cracked by a crab and, by a miracle, the shell was removed.  As an example, over the course of three years, I encountered two almost-naked specimens in one species, Ophiodermella inermis, that I worked on many years ago.

Ophiodermella inermis, photographed in Dyes Inlet, Washington.

Anyway… Raup found that virtually all mollusk and brachiopod shells were basically helical in shape, and that all fundamental shell shapes could be described by only three parameters, 1) the shape of the shell’s aperture, 2) the rate at which the shell’s aperature coiled around the central axis, giving the width of the animal, and 3) the rate at which the coiling moved along the central axis which determines the animal’s length.  As all of the functions occur simultaneously, how each of the parameters varies in relationship to the others changes both the absolute and relative proportions of the shell’s shape.

This diagram below shows how the shell parameters determine the difference in shell shapes for some snails commonly found in marine reef aquariums. The top shows a Nerite; here the shell aperture just moves in a spiral around the axis of coiling and moves outward at a rate that is not very large.  This results in a spirally-coiled shell where the whorls appear to overlap.  The other shells are trochoideans.  And here the parameter of “aperture shape” is circular.  The aperture moves around the axis of coiling at various rates – giving a turbinate or trochoid shape.  Additionally, the aperture moves along the axis of coiling determining whether the shell is squat or elongate.  Although the flat Stomatella seems to be very different from a conical Trochus in structure, with a little thought, it is easily possible to see how those shell shapes are related.

.Shell parameters illustrated by various snail shells; all shells grow in three dimensions but the position of the aperture in each successive whorl may change due to only 3 parameters. A. Growth of a shell where the aperture shape moves in a spiral within one plane; the nerite shell is an example of this. B. Here the aperture moves along the axis of coiling but remains tangent to that axis; the illustrated turbinid is an example of that growth. C. Here the aperture moves along the axis of coiling, but also translates or moves outward from that central axis. An opening called an umbilicus in the center of the shell is the result. The illustrated trochid shows this growth form, with the earlier positions of the growth generating aperture shown in gray. The shell of Stomatella is auriform, an extreme example of the prominence of the whorl translation rate.

Given that all molluscan shells can be basically described in this manner, if shells lack much distinctive coloring, sculturing, or extra ornamentation, it should be apparent that there really are not a lot discrete characteristics that can be used to uniqually differentiate any given shell from all others that are basically similar in shape.

That lack of potential characters is the first factor that has caused taxonomic problems with pyramidellid shells.

The second and third problems were two malacologists, William Healey Dall and Paul Bartsch.  Dall was the first curator of mollusks at the United States National Museum (aka the Smithsonian Institution).  Bartsch was his “disciple” and successor.  As curators at the Smithsonian, a lot (really A LOT!!!) of specimens (= dead shells) were sent to them by various collectors.  As they tried to identify these shells, they often found that the shells were not “quite” like shells in the museum’s collection – or in other museums’ collections.  This meant that these shells were then new to science and needed to be taxonomically, or scientifically, described.  Virtually all animals that are described from United States regions or by American authors have representative or “type” specimens deposited in the Smithsonian’s collections, so they had a lot of comparative material.  Presently, that is a huge number of specimens, several millions.  Back in Dall’s time, the collections were a lot smaller… but still relatively very large…  So, they had a lot of material with which to compare any given specimen in their descriptions.  Thus, if they decided a given specimen was a “new” species the odds would seem to favor the fact that it was new. 

Maybe…

Typically what these two ol’ boys did, was to let specimens accumulate until they had enough to write a short (or sometimes very LONG paper describing them all).  At the time, the custom was to describe a molluscan species on the basis of one shell. 

ONE. 

THE

TYPE.

The type was supposedly an “average” or representative shell that “typified” the species.  By the way, Dall and Bartsch were by no means alone in the way in which they described “their” species.  It was the standard method of the era.  They were, however, especially prolific, and it seems, especially “gifted” with the inability to find unique precise and useful descriptive terms.  Simply put, many of their descriptions are “precisely ambiguous,” they are written in ways that seem to precisely describe the specimen, but which don’t allow a reader to determine if a given questionable shell that they are holding in their hand is from that unique species.  I think this was because they didn’t include much or any information addressing variations between specimens of the same species.

And what about those variations?  Well, Dall, at least paid lip service to the concept of variation, but he generally didn’t include any useful way to describe variations in the species he described.  Any good field biologist knows that variation is quite literally “the stuff of life.”  For example, for little white snails, such as pyrams, if one collects one hundred specimens from a known species, they will vary in length, width, the number of whorls, slight color variations occur, the proportion of length to width will vary a bit, the number of ribs on whorl may vary, and on and on and on…  One specimen really can’t do it.

Nonetheless, the conception of a species at the time, which was reinforced by rules of Linnaean taxonomy implied that there was no variation in a species.  This was a result of considering all species to be divinely created.  If a creator designed each species, he/she/it/they would obviously get it right the first time and there could be no variation.  That was all fine and dandy up until the publication of The Origin of Species in 1859.  Once the concept of evolution became established, the concept of a species HAD to include variation.  And so it did.

In concept.

But in practice…  Well, let’s just say the idea of variability in a species was not an easy one to get across.  Modern descriptive statistics is just that, modern, so at that time there was no formal way to estimate variability.  The concept of a standard deviation wasn’t there.  Even including a range of sizes in a species description was rarely done.

In essence, for any species – the idea of that species was “crystalized” within a single typical specimen, the type.

Over his lifetime, Dall described 5,302 species in every group of animals defined at the time, from mammals to mollusks.  Most, however, were snails.  Bartsch described an additional 905.  The heyday of these descriptions extended from the 1870s through about 1925 for Dall (several years after he died, actually, as Bartsch published some of Dall’s descriptions after his death).  Bartsch retired in 1945 and died in 1960, and I think his last taxonomic publications were in the 1950s.

Modern day molluscan taxonomists who work in the Pacific where these men had the largest taxonomic effect have a love-hate relationship with them.

Love…about 0.000001%,  Hate… well, do the subtraction.

Simply put, it is essentially impossible to differentiate most small snail species described by these men.  They gave lip service to the concept of species variability, but using the typological approach and their writing style such variability was impossible to descibe.  Interestingly enough, that is not the case with many other prolific describers of molluscan species that were writing at the same time.  Henry Pilsbry was another malacologist who described a lot of species; according to his article in Wikipedia, he wrote over 3,000 scientific papers and described over 5,000 species.  His descriptions have stood the test of time well, so the problems with Dall and Bartsch were due to Dall and Bartsch.

How bad is the situation, really? 

Pretty bad.   Really!

For example, if a large collection of pyramidellids or other small snails is taken from one bay or locality, their parameters will vary, of course.  If those specimens can be determined by other means (ecological parameters, for example) they are all found to by one species, it would be nice – satisfying even – to put one valid name on them.  And… by examining the works of Dall and Bartsch, one can often find numerous – perhaps several dozen – entirely satisfactory species names that will fit within that single collection of specimens from a single species from a single small bay.

Amongst the references I downloaded (thanks to Google’s digitizing, many books in the public domain are downloadable) was:

Dall, W. H. and P. Bartsch. 1909. A monograph of West American Pyramidellan Mollusks.  United States National Museum, Bulletin 68. 1-258 pp, 30 pl.

This monograph contains 258 pages of species descriptions…  And 30 plates of illustrations…. As an example , take a look at this one.

This is one of many plates of illustrations showing species of Turbonilla.  Turbonilla is one of the genera of pyrams that has species that will attack Tridacna.  Do you think you could use such images as these to differentiate between any two them reliably?

Could anybody?

When I discuss specific animal groups in my articles for the reef aquarium hobby, I like to give examples of those species…

CORRECTLY IDENTIFIED examples of those species.

And, please excuse me, so that I may now go and start beating my head against the wall.

Because it will feel soooo good when I quit. 

An aside… 

Oh… for those of you who might know mammals, the Dall sheep and the Dall porpoise were named after William Healey… AND here is something I will bet you probably didn’t know.  His name “Dall” was pronounced rhyme with “Gal,” NOT “Gall,” as it is most often used.   See… I even give you a piece of “party” trivia to amuse your friends with.  Of course, if you do so, you risk never being invited to such parties again.

References:
Raup, D. M. 1962. Computing as an aid in describing form in gastropod shells. Science. 138:150-152.

Raup, D. 1966. Geometric analysis of shell coiling: general problems. Journal of Paleontology. 40:1178-1190.

Raup, D. M. 1969. Modeling and simulation of morphology by computer. Proceedings of the North American Paleontological Convention. September 1969:71-83.

Until later,

Cheers,

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