31 May 2005

Back to the Cretaceous with Sam Magruder

The manuscript for this barely 100-page novella was found among the papers of the late paleontologist George Gaylord Simpson (1902-1984) some years after his death by his daughter Joan Simpson Burns, who had the fortunate insight to have it published (The Dechronization of Sam Magruder, St. Martin’s Press, 1996).

Sam Magruder is a 22nd century chronologist who, during an experimental mishap, gets transferred to the Cretaceous, where he arrives buck naked and hungry. Nevertheless, not only does Magruder end up surviving to a ripe old age among the dinosaurs, he even manages, in a rather clever way, to send messages back to the future.

Simpson, who made significant contributions to the evolutionary theory during his lifetime, further enlightens his story by occasional tid bits of evolutionary wisdom. One funny thing I noticed though, is that our hero, a scientist from 2162, still uses feet and miles as units of length. But then again, who knows what units they will actually be using 157 years from now.

There is also a witty introduction by Arthur C. Clarke, who picks the title “A Crusoe of the Cretaceous” for the story, and a long, but unmemorable afterword by the late Stephen J. Gould.

I recommend that you get a copy to read on your next long plane trip to......the Cretaceous (and why not?).

29 May 2005

A day of bioblitzing

This weekend my son and I were at the 4th annual BioBlitz* at New Germany State Park in Garrett Co., Maryland. I had never collected snails in western Maryland before and no one had previously surveyed for snails in this BioBlitz. So, this gave me an opportunity to do a little bit of both.

On Saturday afternoon I had the pleasure of collecting with the very enthusiastic Smith Family, who, after watching me do it for a few minutes, became very good at finding snails, and I think, ended up finding more specimens than I did (my excuse is that there were 4 of them).

Right: a couple of the denizens of New Germany State Park, a Triodopsis and a Ventridens.

This morning I had a nice hike with my son and found more snails and slugs. My preliminary total for the BioBlitz is 10 species of land mollusks, including two slugs. The total will probably go up after I carefully examine the collection.

Below: the rainy weather had brought the philomycid slugs out on tree trunks.

Despite the unpleasantly cold and wet evening we spent in our tents, overall, we had a good time. The participants in the bioblitz were all very eager to go out and find things. And our host and the organizer of the BioBlitz, Eric Savage, was very friendly and helpful. He even had a pizza dinner for us on Saturday night.

We hope to return next year for more species and natural fun.

*A bioblitz is a 24-h biodiversity survey of a designated area, usually a park.

27 May 2005

Friday nite's beer review: Kalinkin from Russia

I bought a bottle of these for $1.94 from the local "beer & wine" store here in Germantown, Maryland. The color of the glass of the bottle made me think it was dark beer, what I prefer to drink, but it wasn't dark at all. It tasted OK, though it was a bit too sweet maybe. I guess I could drink it every now and then.

It was bottled by the Stephan Razin Brewery in St.Peterburg [how they spelled it on the back label], Russia (www.razin.ru - it's almost entirely in Russian and there is no e-mail adress). I suppose the guy on the label is Stephan himself (can we call him Steve?). I haven't the slightest idea who he was, what he did. And why is there what looks like a Viking ship on the cap?


Pavane for a dead slug

Last Saturday afternoon while on a walk near my house, I noticed a shiny track on the sidewalk. It ended at a shriveled object stuck to the hot, dry concrete and hardly resembling a slug.

The slug had probably come out of its hiding place during the night, perhaps when the sidewalk was still wet from the Friday's rain. Then, after the sun rose and things started to get hot, it tried to get away. It was going in the right direction when it ran out of slime just six centimeters short of the grassy field along the sidewalk.

I pressed my fingers on the soil among the grass roots and felt that it was still damp at that hour. Six more centimeters, and the slug would have reached safety.

A snail would have survived. It would have withdrawn into its shell and, provided that it didn't get stepped on, waited until the next rain or the night time when the humidity rose before coming out again. Although at times like this it is good to have a shell, at other times being a slug has its advantages too.

A long time ago, when the snail-like ancestors of slugs started out on the road towards slugdom they began to make smaller and smaller shells. This way, they were able to divert resources from shell making to growth and reproduction. They could grow big and lay big eggs without having to also build big shells. They also became faster, for they didn't have to carry heavy, cumbersome shells on their backs. Moreover, when it got too hot or dry, or when there were predators around, they could squeeze into the nooks and crannies that the snails, because of their shells, wouldn't fit. And they didn't have to cross any hot sidewalks.

Millions of years later on a suburban sidewalk, one of their descendents had to pay the price.

26 May 2005

A colorful alien: Arion subfuscus

The European slug Arion subfuscus comes in different shades of brown, yellow and sometimes even red.

Pilsbry1 gives the location of the first U.S. record of A. subfuscus as Boston and the date as “Before December, 1841”. In gardens, abandoned fields and along the edges of second-growth forests in the northeast U.S., it is now one of the most common introduced slugs, along with Limax maximus, Deroceras reticulatum and Arion intermedius. Unlike Limax and Deroceras, however, both A. subfuscus and A. intermedius penetrate deeper into the woods.

These slugs constitute a part of what is called the “naturalized” fauna of the U.S. Unfortunately, they are here to stay.

1. Pilsbry, H.A. 1948. Land Mollusca of North America (north of Mexico ). Volume 2, part 2, p. 670. Academy of Natural Sciences, Philadelphia.

25 May 2005

Tree hugging slugs

One rainy afternoon at the end of last April I went slugwatching in the woods near my house. Wet and warm weather brings out the native philomycid slugs that like to crawl on the wet trunks of the trees. They seemingly feed on the fungi and the microscopic algae growing on the trunks.

They were indeed there, all over the place. It was gratifying to witness their recovery, along with the trees and the other organisms, in these areas that were once covered with farm fields. They have taken back what truly belonged to them.

Even if there are no slugs visible, you can tell that they have been there from the light colored tracks they leave on the trunks of beech trees. I have seen slugs on trees 4-5 meters above the ground. What I would like to know is where they hide when it’s dry.

24 May 2005

Slug shells: silent witnesses to evolution

A person who is familiar with the snail species in an area can tell most, if not all, of them apart by their shells. This is because a snail’s shell, having a vital function in the survival of its bearer, has been shaped by evolution to fit the specific needs of the snail that carries it. As a result, the shells of different species of snails tend to differ from each other.

Unlike the shells of snails, however, the internal shells of slugs have long lost their functions. They now reside, away from the direct effects of the environment, buried under the slugs’ skin. The shell sits atop some of the vital organs, such as the heart and the kidney. Hence, one could argue that it still has a protective function. But this argument is weakened much when one notices that many slugs don’t have shells at all, yet they get by just as well. Moreover, sometimes a slug’s shell can be so thin and flimsy that one wonders why the slug even bothered to make one.

If the snail shells are species specific, mostly because they are directly subject to natural selection, the reverse argument that follows is that the slug shells that are not selected anymore should not be species specific. This is indeed the case with the internal shells of the slugs in the widespread families Limacidae and Milacidae 1.

These are some slug shells that I found in soil samples collected during a field trip in Istanbul, Turkey in the summer of 2000. All they tell me is that some limacid slugs were present in the area. Otherwise, they can’t reveal their true identities, for they have been silenced by evolution.

1. Reuse, C., 1983. On the taxonomic significance of the internal shell in the identification of European slugs of the families Limacidae and Milacidae (Gastropoda, Pulmonata). Biologisch Jaarboek Dodonaea 51, 180–200.

23 May 2005

Deroceras reticulatum mating

Inspired by the story and a photo of mating Limax maximus at bootstrap analysis , I am presenting an account of the mating of another alien slug from Europe, Deroceras reticulatum (also known as Agriolimax reticulatus).

Like Limax, Deroceras is also a hermaphrodite with each slug normally bearing both female and male organs. However, unlike Limax, Deroceras mates on the ground. They have relatively large penises that they carry inside their bodies and which are everted during mating. The penis has a multi-lobed appendage in addition to a peculiarly shaped stimulator organ (sarcobelum).

Although they are stated to mate usually at night, once I observed them mating at noon in my backyard. Detailed descriptions of their mating behavior have been published1, 2. During courtship, which may take an hour or more, the slugs very slowly turn around in a circle while stroking each other with their sarcobela protruding from their genital openings. You can see the worm-like sarcobela in the picture on the left.

During the actual mating, they don't insert their penises into their partners' vaginas, but exchange sperm externally. In the picture on the right their penises appear to have been fully everted and intertwined. The arrows are pointing at what seem to be the appendages on the penises. This phase of the process takes a relatively short time and after which the slugs separate.

Here is a question for the readers to think about: why do these slugs always circle each other clockwise during courtship?

1. Karlin, E.J. & Bacon, C. 1961. Courtship, mating and egg-laying behavior in the Limacidae.
Transactions of American Microscopical Society, 80:399-406.
2. Webb, G.R. 1961. The sexology of three species of limacid slugs. Gastropodia, 1:44-55 .

21 May 2005

Marissa-Cat in the rain

There's gotta be a dry spot here somewhere.

20 May 2005

How to break the 2nd law and (almost) get away with it

I had been ruminating about writing something along these lines and the post I read this morning about the American thermodynamicist J. W. Gibbs over at the Culture of Chemistry provided the impetus.

Gibbs' name is immortalized as "G", the symbol for "free energy". In P. W. Atkins' words, the free energy of a process, given by the following equation, is its single most important thermodynamic property1.

Free energy change = Total energy change - (Temperature x Entropy change)

For any process to be spontaneous, its free energy must decrease. In other words, the change in free energy must be a negative quantity.

If you look at the free energy equation carefully, you will see that there are three combinations that will result in negative changes in free energy2:

1. The entropy increases and the total energy decreases. In other words, both terms on the right hand side of the equation are negative quantities.

2. Both the entropy and the total energy increase, but the absolute value of (temperature x entropy change) is greater than the absolute value of the total energy change, so that the net change in free energy is still negative.

3. Both the entropy and the total energy decrease, but the absolute value of the total energy change is greater than the absolute value of (temperature x entropy change), so that the net change in free energy is still negative.

Here is one way of expressing the famous 2nd law of thermodynamics (again, from Atkins): Natural processes are accompanied by an increase in the entropy of the universe.

Now, if you go back and read the possibility #3 that I listed above, you will see that it applies to a process during which the entropy is actually decreasing. So, is the process breaking the 2nd law? It may seem that way, but it is not.

What is happening is that to satisfy the requirement that the change in Gibbs' free energy be negative, the process is releasing heat to its surroundings. The released heat is increasing disorder in the surroundings by making the components of the surroundings move faster, so to speak. And increased disorder means increased entropy. Therefore, the net change in the entropy of the universe is still an increase. No law is broken, everyone is happy.

There is, however, a way to avoid the 2nd law. But that comes with a heavy price to pay. I will leave that to a future post.

1. My definitions and notations follow Atkins, P.W. 1984. The 2nd Law. W.H. Freeman & Co.
2. For simplicity, let's assume that the temperature is always positive.

19 May 2005

Spacious shells 3

The examples of pulmonate snails with extra space in their shells that I had in my two previous posts on this subject (#1 and #2) were all relatively large. What about smaller snails? Do they also carry extra space in their shells?


This photograph shows a live Euconulus polygyratus. Its shell is 2.3 mm long and 2.8 mm wide. We found this snail a couple of weekends ago during our field trip in Cunningham Falls State Park. A few days after I brought it to the lab, I noticed that the snail had become dormant on the underside of the lid of its container. As the photograph shows, the snail’s body (arrow) was about a third of a whorl behind the aperture.

So, yes, even small snails carry extra space in their shells.

18 May 2005

Snake's tails 2

This is an eastern garter snake (Thamnophis sirtalis), a nonpoisonous species. I ccasionally come across them usually near creeks in Black Hill Regional Park, Germantown, Maryland. I photographed this one in May 2000. It was about a half a meter long (the tulip poplar leaf provides a scale).

Thamnophis sirtalis is a widespread species with many color forms. For more information, try these links.


16 May 2005

Soup d’jour: organic primordial

According to a paper in last Friday’s Science1, the escape of hydrogen from early Earth’s atmosphere might have taken place at much slower rates than previously thought. As a result, the authors explain, the rate of formation of prebiotic organic compounds by electric discharge in this hydrogen-rich atmosphere would have increased. These organic compounds would then have rained into the oceans creating an organic soup, and thereby setting the stage for the origin of life.

So, drink your soup quickly, before it starts to evolve!

1. Tian, F., Toon, O. B., Pavlov, A. A., De Sterck, H. 2005. A Hydrogen-Rich Early Earth Atmosphere. Science 308:1014-1017. Abstract

14 May 2005

Snake's tails 1

Following Henry's lead at his Webiocosm (here and here), I am putting up some snake photos from my collection.

This is an adult worm snake (Carphophis amoenus), a nonpoisonous species. We found this specimen last year in the woods across from Plummers Island, along the Potomac River in Maryland. I have been told that this was the first record of this species for that area. After taking its pictures we released it back to its home.

11 May 2005

The curse of the dumb mummy

Through Zinken, I was directed to a piece on an upcoming National Geographic movie about the alleged curse associated with the opening of the tomb of Tutankhamen in Egypt in 1922. The legend of “the curse” started with the death of Lord Carnarvon shortly after attending the tomb's opening. National Geographic states that a recent theory attributes Carnarvon's death to exposure to ancient, toxic pathogens from the sealed tomb.

This reminded me of a study in the December 2002 issue of the British Journal of Medicine1 that compared the fates of 25 Westerners who were present during the opening of the tomb of Tutankhamen with those of a control group of 11 Westerners who were in Egypt at that time, but did not visit the tomb. Although the group of 25, who would have been exposed to “the curse”, did live shorter lives (mean age at death: 70 years) than the controls (mean age at death: 75 years) and did have shorter survival after the date of exposure (20.8 versus 28.9 years), the differences were not statistically significant. The conclusion of the study was that there was no evidence to support the existence of a mummy's curse.

During the preparation of a body for mummification, the ancient Egyptians removed the person’s brain—amazingly—through the nose, piece by piece. So, fear no mummy who returns to life; not only will he or she be almost as dumb as some of our elected public officials, but you won’t be exposed to a curse either.

1. Mark R Nelson, M.R. 2002. The mummy's curse: historical cohort study. British Journal of Medicine, 325:1482-1484. pdf

10 May 2005

Cast from the past: the first American papers on American mollusks

Thomas Say’s article titled “Conchology” that came out in the winter of 1817 in the First American Edition of the British Encyclopedia by William Nicholson was the first paper on American mollusks written by an American author1, 2. The first edition of the Encyclopedia is apparently very rare; the digital collection of the Academy of Natural Sciences of Philadelphia provides a copy of the 3rd 1819 edition. The figure on the right shows Say’s drawing of Helix albolabris (now Neohelix albolabris) from Plate 1, one of the land snails Say described in his article.

A few months later, in May 1817, the first issue of the Journal of the Academy of Natural Sciences was published, in which Say had his second paper on American mollusks3. Among the species Say described, without drawings, was Succinea ovalis.

1. Weiss, H.B. & Ziegler, G.M. 1931. Thomas Say: early American naturalist. Charles C. Thomas.
2. Johnson, R. I. 1975. First paper on the conchology of the United States by an American author, Thomas Say, 1817. Journal of the Society for the Bibliography of Natural History, 7:265-267.
3. Say, T. 1817. Description of seven species of American fresh water and land shells, not noticed in the systems. Journal of the Academy of Natural Sciences of Philadelphia, 1:13-16. [The Academy’s Web site gives the publication date of this first issue as May 1817.]

07 May 2005

A snail hunting trip to Catoctin Mountain

Taking advantage of the weather mildly reminiscent of spring, I went to Cunningham Falls State Park (Frederick Co., Maryland) this afternoon with Butch Norden of Maryland Department of Natural Resources and Tim Pearce of Carnegie Museum of Natural History.

We spent about 2 hours at the bottom of a steep rocky hill searching for snails and slugs. Among some of our more interesting finds were several of these snails, possibly Triodopsis juxtidens

and many of these small slugs, a species of Pallifera.

There were also small succineid snails. We found several of them attached to leaves and pieces of litter. This one was on a tulip poplar seed.

When succineids are actively moving around, they leave the impression that they are too big for their shells. But as this picture shows, they do fit into their shells when they are dormant.

05 May 2005

How to speak Turkish with an Adobe Acrobat accent

OK, this post has nothing to do with natural history, but I’ll make it fall under “and such”.

Did you know that Adobe Acrobat 6.0 and higher versions have a feature called “Read Out Loud”? It’s under “View” or you can use the combination Shift+ Ctrl+V (to read the page you are on). It does a pretty good job of reading basically any English text. But what about other languages? To find out, I attempted to read out loud a Turkish text, and expectedly, got unintelligible gibberish. The reason is simple: Acrobat reads the text as if it were English, although in reality, the pronunciation of Turkish is as different from English as a crow is from an alligator (there is the connection with natural history). Furthermore, Turkish uses several characters that are not in the English alphabet, and which Acrobat can’t recognize.

The solution I came up with was to rewrite a Turkish text as phonetically as possible using only English characters. It took many trials and errors to get not only the sounds, but also the accents right. If you compare the proper Turkish text with the pdf version, you will see that I had to break apart several words and use commas in unusual places so that the accent would fall on the right syllable. Here is the Turkish text followed by its translation.

Merhaba, benim adım Aydın Örstan. Ben Kastamonu’nun bir köyündenim. Size kısa bir maymun hikayesi anlatacağım. Bilirsiniz, maymunlar akrabalarımız olurlar, sizin ve bizim. Bir gün bir maymun güzel bir bahçeye çıkmış. Bahçede çiçekler varmış, güller ve papatyalar. Karşısına bir de bir insan çıkmış. Maymun insana, “Sen de maymundun, ama kendini rezil ettin” demiş. İnsan da, “Biliyorum, bende ne maymunluk, ne de insanlık kaldı” demiş.

Bunu duyunca, maymun insanın omzuna çıkmış ve “Çok acıktım, yemek var mı? Bir az pastırma ve domates istiyorum. Bir bardak da bira ver, lütfen” demiş. Ne kadar akıllı bir maymunmuş.

Hoşca kalın.

(Hello, my name is Aydin Örstan. I am from a village of Kastamonu*. I will tell you a short story about a monkey. As you know, monkeys are our relatives, yours and mine. One day, a monkey went out into a nice garden. In the garden there were flowers, roses and daisies. The monkey also came upon a human. The monkey said to the human, “You used to be a monkey too, but you have made a spectacle of yourself”. The human replied, “I know, now I am neither a monkey nor a human”.

When the monkey heard this, it jumped up on the human’s shoulder and said, “I am very hungry, is there anything to eat? I want some pastirma* and tomato. Also, please give me a glass of beer”. What a smart monkey it was.

Take care.)

The phonetic version of the Turkish text saved as a pdf file is here. To listen to it, first, download it, then open it with Adobe Acrobat, and then make Acrobat read it out loud (don’t forget to turn on the speakers). It basically sounds like a native English speaker speaking Turkish with a heavy accent. But it is understandable to native Turkish speakers; it sounds funny, though. It can be improved further, but it already took too much of my time.

And what’s the point, you ask? Nothing. It was just a fun exercise.

*Kastamonu: a province in north-central Turkey.
*Pastirma: a delicious meat product native to Turkey and made by curing meat with spices.

02 May 2005

Who can beat nature, mothers or snails?

Every individual in a population of a species is more or less unique; even a pair of identical twins or clonal individuals may differ from each other in environmentally induced details. Natural selection acts on this variation among the members of a species, but only the genetically determined variation is relevant from one generation to the next.

Intuitively, one expects limits on the variability of a character. Fanciful legends and children’s tales notwithstanding, giant men or thumb-sized boys cannot exist, because numerous morphological and physiological constraints would prevent such creatures from being viable. In natural populations what controls the limits of variability is stabilizing selection. For example, in a more or less stable environment, the medium-sized members of a population are usually more likely to survive than those that are either very small or very large. Therefore, it should not be too surprising that the relative standard deviation values for the dimensions of various anatomical characters, not only of mammals1, but probably of any animal species lie between 4 and 10%.

This means that under the watchful eyes of natural selection, mothers2 are not any better than tiny snails3 when it comes to going beyond the limits.

1. Simpson, G.G., Roe, A., Lewontin, R.C. 1960. Quantitative Zoology. Harcourt, Brace & World.
2. The data for the heights of 1052 British mothers are from Pearson, K. & Lee, A. 1903. On the Laws of Inheritance in Man: I. Inheritance of Physical Characters. Biometrika, 2:357-462.
3. The data for the diameters of 131 adult specimens of the tiny snail (mean diameter= 2.2 mm) Vallonia excentrica, collected in my backyard, are from an unpublished study of mine.
4. I acknowledge that a comparison of the variabilities of the heights of humans and snail shells was first presented, using different sets of data, by A. E. Boycott. 1928. Conchometry. Proceedings of the Malacological Society, London. 18:8-31.