SNAIL'S TALES

Not exactly geocaching

2009-11-26T16:03:00.000-05:00

While rummaging in the woods for snails and slugs earlier today, I came upon a well hidden geocache box. What are the chances of finding one of these when you are not actually looking for one?

I opened it hoping to plunder the contents, but there were only a log book and assorted junk, including a golf ball and a small plastic doll. I am not sure what the rules of this game are. Are you supposed leave something in the box? I didn't leave anything or take anything; the 2 snail shells I had found earlier were too good to part with.

I did enter the URL for this blog in the log book, though.

One more 19th century painting of a terrestrial gastropod and a malacologist's story

2009-11-24T23:04:00.001-05:00

This picture of the snail formerly known as Helix aspersa adorns the cover of M. S. Lovell's 1867 book The edible mollusks of Great Britain and Ireland with recipes for cooking them. The book is available at the Biodiversity Heritage Library. I have scrolled thru the book quickly and noticed, in addition to recipes, many records, natural history observations and other miscellanea related to edible mollusks and also 12 colored plates.

The following anecdote is from page 20 and was taken from the famous 19th century malacologist E. A. Rossmässler's Reise-Erinnerungen aus Spanien.

Much amusement was afforded to the Spaniards, by Rossmässler throwing away the delicate animal, and only retaining its shell, which to them was worthless, but most valuable to him as a conchologist. Upon one occasion, on arriving at a posada, he found the hotel people sitting down to their midday meal, before a great dish full of snails. He says:—"One look satisfied me that they were of a rare kind, for which I had sought in vain; and I immediately seized upon some of the empty shells, which caused a universal laugh.

To a modern malacologist the snails' bodies would be as valuable as their shells. Rossmässler would undoubtedly have done the future malacologists a great favor if he had saved a snail or two along with their shells.

The previous 19th century painting of terrestrial gastropods was here.

The Aqueduct of Vallonia

2009-11-23T21:53:00.000-05:00

This is the Alexandria Aqueduct, or what is left of it, in Georgetown, Washington, D.C. According to Mike High's The C&O Canal Companion (1997), the aqueduct once connected the C&O Canal to another canal (not named in the book) on the Virginia side across the Potomac River, which is visible on the right (the Key Bridge is in the background). The C&O Canal is towards the left of the aqueduct in this picture.

I was there last Friday. I noticed that parts of the walls of the aqueduct were wet from water seeping out from between the rock blocks (it had rained the day before). A close inspection revealed tiny snails crawling on a section of the wet wall partially covered with red ivies (towards the lower left in the photo). A closer inspection revealed that the tiny snails were Vallonia.

They are either Vallonia pulchella or V. excentrica, the 2 being somewhat hard to distinguish. Their shell diameter is ~2.3 mm.

The next time I am there I will check again to see if the snails are always out on the wall.

Bipalium adventitium — Part 4

2009-11-22T23:24:00.000-05:00

In part 3 of this series, I attempted to feed a slug, Megapallifera mutabilis, to my "pet" planarian Bipalium adventitium. The planarian refused. In the comments, Megan P. suggested that I repeat the experiment with baby slugs. You see, as long as it is in the name of science, we can even feed babies to predators. We are collecting data here.

I thought Megan's idea was worth a try, but I was freshly out of baby slugs. Luckily, Megan had some and was willing to part with a few. So, last Thursday I visited her lab at the University of MD and returned home with 3 juvenile Philomycus carolinianus, another native species in our favorite slug family the Philomycidae. And early this evening, I offered them to El Depredador that had been waiting patiently in the basement.

So far the slugs have survived. But the night is young and there is plenty of time for a surprise pharynx eversion.

To be continued.

Fluid trends

2009-11-21T17:03:00.000-05:00

In the previous post in this series, the index of satisfaction (IS = optimism / happiness) had stabilized for a change. However, the most recent data clearly demonstrate that the long term trends are fraught with uncertainty.

A sharp drop followed by a gradual recovery was nobody's guess. And once again, we don't know if it's optimism that's going thru a turbulent period or happiness is fluctuating depending on the amount of wine intake.

I will continue to monitor this crucial index and provide updates.

How about a long penis covered with spikes?

2009-11-19T17:30:00.000-05:00

The arrow is pointing at the pointed papillae covering the penis of Chondrus tournefortianus. I don't know what function the papillae may have.
The picture shows the everted penis of the land snail Chondrus tournefortianus. This hapless pair was mating on a hillside at the outskirts of the city of Kastamonu, Turkey one cold and wet morning in October 2008 when I chanced upon them. Not only did I intrude upon their privacy by photographing them, but I also pulled them apart to see if their mating was anatomically reciprocal.

Remember that pulmonate snails, and that is what these are, carry both male and female; in other words, they are hermaphrodites. Therefore, when they mate, it is possible for each snail in a pair to use its penis to inseminate its partner. In many snail species, mating is indeed anatomically reciprocal*. But in some species only one snail acts as the male and gets to inseminate its partner.

One way to determine if the mating of a pair is anatomically reciprocal is to kill them in copula and then to dissect them. I don’t particularly like killing snails, especially if they are in the process of performing a fundamental evolutionary act, that is, passing on their genes. So instead, I pull them apart while watching them under a microscope or a magnifying glass, if I am in the field, and hoping to see their penises as they are being withdrawn (more about that technique here). Other than one interrupted coitus, no damage is done.

In the case of this particular pair of Chondrus tournefortianus, after I separated them, I saw the penis of only one snail and, therefore, concluded that their mating was anatomically unilateral. The details of this lucky encounter and how it has contributed to our knowledge (or the lack thereof) of the family Enidae, to which this species belongs, have just been published in a short paper of mine in the journal Zoology in the Middle East. You may read it here. The paper also has a photo of the mating snails before I took the matter into my hands.

*Strictly speaking, anatomical reciprocity doesn’t necessarily mean reciprocal insemination; an individual could mate without contributing sperm. Anatomical reciprocity can also be simultaneous or sequential. Yes, I know, it does get complicated.

Another 19th century painting of terrestrial gastropods

2009-11-17T20:36:00.000-05:00

This is Tafel XI from an 1889 paper by E. von Martens*. The drawing of the live snail on the bottom represents a Helix asemnis venusta, a species of southwestern Turkey and the nearby Greek Islands.

The previous 19th century painting of terrestrial gastropods was here.

*E. von Martens. 1889. Griechische Mollusken. Archiv für Naturgeschichte 55:169. (Full text from the Biodiversity Heritage Library.)

A true confession: I was Otto Mann

2009-11-16T18:51:00.001-05:00

The magazine American Rationalist praises itself for being an "Alternative to Superstition and Nonsense" for over 50 years. I subscribed to it for several years in the 1990s. Then I got tired of it, although I don't quite remember why, and ended my subscription.

However, I did publish one article in the AR. It came out in the November-December 1993 issue. It was titled Life, Death and Mind Transfer and was about, well, life, death and mind transfer.

Recently, I read again what I had written and quite liked it. Although, I admit, there isn't much in it that was original—at least it seems that way to me now, almost 17 years later. Mind transfer has been a favorite subject of many a science fiction story.

Nevertheless, I decided to scan it and upload it to my library for all to read. Here it is.

The funny thing about this article is that I published it under the pseudonym Otto Mann, although, again, I don't quite remember why. If anyone doubts that I was Otto Mann, I do have a short note to that effect from the late Gordon Stein, the then editor of AR. I also cite one of my own papers for whatever it may be worth.

A few years later I published another article somewhere else as Otto Mann. I will put that up some other time.

Bootleg proceedings of the 3rd OVUM meeting

2009-11-15T17:10:00.000-05:00

The 3rd annual meeting of the Ohio (River) Valley Unified Malacologists (OVUM), organized by Tim Pearce, took place at the Carnegie Museum of Natural History in Pittsburgh yesterday. There were 14 participants and 11 presentations. Here are the speakers and very brief summaries of what I thought they talked about in the order of presentation.

Charlie Sturm (CMNH): Ongoing attempts to locate the field notes that were associated with the freshwater mollusk collection of Herman P. Wright that was donated to the Carnegie Museum in 1932 and which has since been sitting uncatalogued in a drawer.

Tim Pearce (CMNH): Studies to correlate the weather data with the short-term movements of snails.

Francisco Borrero (Cincinnati Museum of Natural History): taphonomic evidence for turnover in the freshwater mussel community in the Ohio Brush Creek.

Aydin Örstan (CMNH): Results of the survey done to determine the present range of Cepaea nemoralis in Frederick County, MD that was introduced by the late Wayne Grimm in 1969.

Andrew Turner (Clarion University): Elevated pH, caused by nutrient enrichment (increased phosphorus levels), may interfere with the freshwater gastropods' detection of the chemical cues produced by their predators.

Beth Meyer (Western Pennsylvania Conservancy): Mussel, fish and macroinverterbate survey of the French Creek, PA.

Nevin Melte (WPC): Recent PA Fish and Boat Commission activities related to mussels. These included the collection and relocation of a large number of mussels from behind Carter’s Dam prior to its removal.

Emily Cholak (Clarion University): Effect of predation risk induced by fish and crayfish on the population dynamics of their prey, the freshwater gastropod Helisoma trivolvis.

Kip Brady (New Philadelphia High School): Ecological projects involving freshwater gastropods in high school biology classes. Will the students develop a better appreciation of wildlife?

Tim Pearce (CMNH): Laboratory experiments to determine if the slug Philomycus carolinianus likes to aggregate with its conspecifics?

Aaron Stoler (University of Pittsburgh): How the presence of leaves from different species of trees in the water affect the survival of tadpoles and the gastropods Physa acuta and Helisoma trivolvis.

T. rex was there too.

Not necessarily profound questions from my notebooks – Part 1

2009-11-13T17:40:00.001-05:00

—The results of one set of data may be interpreted in conflicting ways to produce more than one truth statement. How can a minimalist research program avoid this difficulty?

—Once while walking, I encountered 5 Canada geese. Two of them started honking and flew away, but the other 3 simply walked out of my way. Will we ever be able to understand what factors create such behavioral differences at a given moment?

—Do the internal vestigial shells of slugs have a function?

—How small is the smallest piece of cytoplasm that can be considered alive?

—Is there a dimensional threshold below which a brain cannot develop consciousness or is consciousness present all the way down to the smallest animals with brains?

Grey heron in the C&O Canal.
To be continued.

Absence of evidence could be evidence of absence

2009-11-12T17:57:00.000-05:00

You don't see an elephant in this picture, do you? I don't see one either. In fact, when I was there I looked around carefully, but did not see any elephants. Besides, this picture was taken in Maryland where no wild elephant has ever been recorded. And when I took this picture, there was no nearby circus or zoo reporting a missing elephant.

Therefore, I conclude that my observations and this photograph prove that there was no elephant at that point at that time.

I just proved a negative.

OVUM Meeting will be this Saturday

2009-11-10T19:08:00.000-05:00

The 3rd annual meeting of OVUM, the Ohio (River) Valley Unified Malacologists, will be held on Saturday 14 November 2009 at the Carnegie Museum of Natural History, 4400 Forbes Ave., Pittsburgh, PA.

From the e-mail announcement:

This one-day meeting will run from (9:30) 10 am until the last presentation (to end by 5 pm at the latest). Light refreshments such as fruit, bagels, coffee, tea, and water will be available from 9:30-10:00 am. The meeting will be held in Multipurpose Classroom B. Participants should sign in at the Security Office at the Portal Entrance (off the Parking Lot), then follow signs a short distance to the meeting room.

The meeting is open to professionals, amateurs, and students; basically anyone who has an interest in mollusks. OVUM has no dues, officers, abstracts, or publications. Even busy people can spend a day networking and talking about mollusks.

Please limit presentations to 15 minutes.

For more information contact Tim Pearce (PearceT AT CarnegieMNH.org).

I am planning to go, barring last minute changes to my plans.

Flattened fauna of sidewalks - Part 5

2009-11-09T19:32:00.000-05:00

Part 4 of this series came out in December of last year, almost a year ago. I follow the better late than never principle and continue along.

The first victim of this installment is a spider of some sort. It was more shriveled up than flattened.

Next, we have a squished mantis on a parking lot. It was definitely a case of hit and park. Despite all that incessant praying, the mantis had a grisly death. As they say, nothing fails like a prayer. Ha, ha, ha!

And here is a first for this series: a flattened mammal, a shrew probably. It comes with an assortment of corpse-licking flies. Enjoy!

To be continued...

Garter snake in C&O Canal

2009-11-08T16:46:00.002-05:00

Last Friday, I was watching a couple of mallards swimming in the C&O Canal near Georgetown. Suddenly, a long, skinny object appeared in the water and started undulating rapidly towards the bank. I gazed at it in amazement for a few seconds before my brain circuitry announced that it was a snake. By the time I finished fumbling with my bag and managed to take my camera out, it had left the water and disappeared. Then I spotted it among the mud covered leaves climbing up the bank (I turned the picture sideways to make it fit the page better). Two shots were all I could take before it disappeared again, this time below the cliff I was standing on.

This is a garter snake (Thamnophis sirtalis). In the original post I had identified it as a ribbon snake (Thamnophis sauritus). However, one commenter indicated that it was instead a garter snake (see below). After I obtained confirmation from another source, I revised the post.

Rain drain on a windy day

2009-11-06T20:20:00.000-05:00

Butterfly (and dandelion) in November

2009-11-05T19:20:00.000-05:00

This is the best shot of this butterfly I saw yesterday. Today at the same spot, there were 2 of them frolicking, but they disappeared before I could approach them.

It is one of the sulphurs, either the clouded sulphur (Colias philodice) or the orange sulphur (C. eurytheme). I don't know how to tell them apart.

I don't want to know what muktuk tastes like

2009-11-04T17:57:00.001-05:00

In this post back in April 2008 I asked myself the question of how a person who eats only meat can avoid getting scurvy, vitamin C deficiency.

Not too long ago, a New Scientist reader asked a similar question: how do traditional Inuit avoid scurvy? An answer has been given in this week's issue of the magazine. The Inuit apparently avoid succumbing to scurvy by eating something called muktuk. Muktuk consists of whale skin and blubber and is high in vitamin C. Eating enough of it would satisfy their vitamin C requirement.

The answer to my own question was that the yak hunter Aldat, the subject of my post, could have avoided scurvy by eating tongues and liver of yak.

As for me, I think I will go get a glass of orange juice.

A spider that had its nest on a sycamore leaf

2009-11-03T22:12:00.001-05:00

One windy day about 10 days ago, the sycamore tree on our street lost many of its leaves. I happened to be passing by and picked up one of them. While examining the leaf, I noticed that one lobe was attached along a vein to another lobe by silky material. I pulled the lobes apart and out came a small spider.

Luckily the spider stayed on the leaf while I brought the leaf in and took a series of pictures. Subsequently, it even went back into its partially destroyed abode.

Obviously, this spider lives high up on the trees. But where does it go when the autumn comes and the leaves fall? Does it prefer sycamore trees, which have rather large leaves? After the photo session, I put the leaf behind some bushes in my yard. As of this afternoon, it was still there, but I didn't check to see if the spider was still on it. I'll do that in a few days.

I just posted the pictures on BugGuide.net. Maybe someone will identify the spider.

The view from inside the nostril

2009-11-02T19:47:00.000-05:00

I don't claim to be an artist. But then again, what is art and what does one need to create to become an artist? I do have a few creations of my own. For what it's worth, here is one of the oldest surviving ones.

Blue ballpoint pen on cheap paper. 7x10 cm. Now slightly faded.
The detailed title explains what it is depicting: The outside scenic view as seen from inside the nose—thru the nostril—of a man. Those 2 scimitar-shaped things are nose hairs, while the irregular entity on the right is mucus. I used to wear my watch on my right wrist. Note that the right hand visible outside the nose is also wearing a watch. So, this is presumably a self-portrait of sorts.

It is dated 15 December 1976, midnight. Arguably, a piece of "art" like this can only be created late at night, preferably after midnight when the time is usually ripe for finding out what it is all about.

If Salvador Dalí had doodled this, it would be worth a hefty sum now. But, sigh, I am no Dalí...

Bipalium adventitium — Part 3

2009-11-01T20:07:00.001-05:00

Bipalium adventitium is a predatory terrestrial planarian. Klots (1960) reported that B. adventitium preyed on "small annelids" as well as on slugs and insect larvae. He did not, however, give details or specify what species of slugs the planarians had eaten. According to recent studies, B. adventitium preys exclusively on earthworms. For example, Ducey & Noce (1998) reported that their specimens did not eat 2 species of slugs (Arion sp. and Deroceras sp.) that were offered to them.

I have had one captive B. adventitium since the end of September. I have fed it 2 earthworms and I have also been testing to see if it will eat the native northeast American slug, Megapallifera mutabilis. In the first test I did 2 weeks ago, 2 slugs survived about 20 h in the same container with the planarian. On several occasions, I observed the planarian contacting the slugs and also crawling on them, but it never, as far as I could tell, attempted to attack them by everting its pharynx (yes, that's what they do).

Touch but don't eat: Bipalium adventitium making contact with a Megapallifera mutabilis.
Tonight's test started 3 hours ago. The planarian hasn't eaten in 20 days. As of 10 minutes ago, the slug was still alive.

The experiment continues in Part 4.

Ducey, P.K. & Noce, S. 1998. Successful invasion of New York state by the terrestrial flatworm, Bipalium adventitium. Northeastern Naturalist 5:199-206.
Klots, A.B. 1960. A terrestrial flatworm well established outdoors in the northeastern United States. Systematic Zoology 9:33-34.

2 more data points (or is it datum points?)

2009-10-30T17:50:00.000-04:00

Very little research has been published on the life cycle, ecology, behavior and the general biology of the native slugs (family Philomycidae) of northeastern North America. Megan Paustian and I started doing some work on the water loss and regain characteristics of one species, Megapallifera mutabilis, early in the spring of this year (see this post).

At about the same time, I decided to understand their annual generation cycle better, especially to figure out if adults survive the winter. It's a simple project, really. For 2 years, I will measure the body dimensions and/or weights of live slugs throughout the year. That's about it. The collective data will show how the members of the population change during the year. The important thing is to take as many measurements as possible on relatively warm days in December and also towards the end of March as soon as the weather starts to warm up. If there are large slugs in December and in March that will mean that the adults survive the winter.

The photograph shows 2 of the slugs getting weighed in the field about a week ago. They were adults and quite heavy, as far as this species goes.

Remains of a meal

2009-10-29T20:01:00.000-04:00

In the bosom of a very distant relative

2009-10-28T16:53:00.001-04:00

Among the numerous bone and mollusk shell fragments scattered throughout our yard is this old, thick clam shell. I have no recollection of where it came from and no idea what species it may have once represented.

The other day when I picked it up to move it elsewhere, I found these 3 slugs, Deroceras reticulatum, safely nestled on the underside of it.

The last common ancestor of gastropods and bivalves must have lived sometime in the Cambrian, more than 500 million years ago*. That makes them very distant relatives indeed. Nevertheless, I had no intention of interfering with their family union of sorts. I returned the clam shell with its inhabitants to its spot.

*Here is a brief intro to mollusk evolution.

Fall of the fallen beech

2009-10-27T17:23:00.000-04:00

This is the horizontal beech tree that refuses to die. I visited it last weekend and saw that its leaves had turned yellow. Will it sprout green leaves next spring? We shall find out.

How science differs from pseudoscience - Part 2

2009-10-26T16:14:00.001-04:00

The main, and perhaps the defining, characteristic of the domain of scientific knowledge (DSK) is that the units of information (or provisional truth) within the DSK form a network. This network is possible because the units of information do not contradict each other. And the outcome of this network is that the units of information support each other.

For example, our understanding of the essential processes of biology rely on and do not contradict the principles of physics and chemistry (no, the processes of life do not violate the 2nd law of thermodynamics). Our understanding of the essential processes of evolution, on the other hand, are supported by even additional scientific disciplines, for example, geology.

This is, of course, an idealistic description of science. There are always some minor contradictions within the DSK, because our understanding of nature is incomplete. One purpose of scientific research is then to reduce the number of the existing inconsistencies and, ultimately, to eliminate them all.

We can visualize the DSK as an N-dimensional information space without a definite center and with fuzzy or diffuse boundaries. The boundaries are not definite, because at the threshold of our existing knowledge there are always uncertainties.

In contrast, pseudoscience and religion lack comparable networks of compatible and mutually supportive truths. And their domains of knowledge have extremely diffuse boundaries. You want to be religious? Then you must pick one out of the many choices you have, because all of the existing religions are mutually exclusive. And besides, they all have severe internal contradictions.

There are 2 processes that advance science: (1) piecemeal accumulation of information either inside the DSK to fill in a gap (yes, there are also gaps) or at the edge to expand the boundary slightly; (2) revolutions or “transformations of paradigms” in Thomas S. Kuhn’s words.

Although Kuhn* may have believed that science advances primarily by revolutions, I don’t see why both processes cannot operate in tandem.

An observation done by a scientist represents the 1st process and the outcome is that some new bits of information are added to either the inside or the boundary of the DSK. For our purposes here, we are interested only in the boundary additions.

The crucial question is, How far from the boundary do new additions fall? The answer is, not too far; in fact, they fall quite close to it. They must fall quite close to the boundary. Otherwise, they will threaten the integrity of the DSK.

Part 1

To be continued.

*Disclaimer: I have so far read only a dozen or so pages of Thomas S. Kuhn’s often-cited 200-page essay The structure of scientific revolutions (2nd ed., 1970). My opinions of his opinions may change as I continue to read and understand his arguments.