Assiminea succinea and her operculum

Yesterday's post was about the tiny semi-terrestrial snail Assiminea succinea and a simple immersion test I had subjected them to in Florida last week. Tim Pearce, in his comment, questioned the identification of the snail. Because the snail in the pictures had eyes at the tips of its tentacles and because no operculum was visible in the pictures, Tim wondered if the pictured snail was instead a common land snail.

A little bit of background information may be necessary to clarify Tim's comments. The land snails that are familiar to most people have 2 pairs of tentacles with the longest pair carrying eyes at their tips. They also don't have opercula. Those are the pulmonate snails in the group Stylommatophora. Among their evolutionarily closest relatives are the snails in the Basommatophora, the adults of which also lack opercula, but have their eyes at the bases of their 1 pair of tentacles. Here is an example: Melampus bullaoides.

Now the plot starts to thicken. The species in the 3rd pulmonate group the Systellommatophora also lack opercula, but have eyes on the tips of their tentacles. In contrast, all other non-pulmonate land snails have opercula and their eyes are at the bases of their 1 pair of tentacles. Here is an example: Pomatias elegans.

To further thicken the plot, I should add that most marine snails, the polyphyletic prosobranchs, have their eyes at the bases of their 1 pair of tentacles and many have opercula.

So, if the snail that I identified as Assiminea succinea didn't have an operculum, it would likely to be a stylommatophoran, although, as Tim noted, it did not have 2 pairs of tentacles. The latter trait is, however, not a universal one among the stylommatophorans as Tim also noted. For example, the snails in the genus Vertigo have only 1 pair of tentacles. Here is an example: Vertigo gouldi.

Confusing? Tell me about it.

Fortunately, to settle the matter quickly I remembered that I had additional pictures of the subject snails and their opercula. Here is a set showing how the little Assiminea succinea comes out of its shell. In the 1st photo the aperture is mostly covered by the thin operculum, while in the 2nd photo, the snail's foot is pushing the operculum (arrow) out of the way. Those little elongated things visible thru its shell, and also outside the shell, are fecal particles, which is another characteristic that separates non-pulmonate snails from at least the stylommatophoran pulmonates; in the latter group, as far as I know, the feces are always in the form of strings and never expelled as individual particles.

I will leave the discussions of the evolutionary implications of all of this, which Tim's touches upon in its comment, to future posts.

Assiminea succinea is in the family Assimineidae. Here is a brief discussion of the characteristics of the family. A new Assiminea species, A. mesopotamica, was described last year by Glöer et. al (Mollusca 25:3, 2007). Their description notes both the presence of an operculum and the location of the eyes.

Attack of the prodigies

I wrote about my "plans" for the stupid intellectually challenged Americans in this post. At the opposite end of the spectrum, there are, of course, those who are too bright and too young. The Guardian reports that

There are nearly 8,000 under-18s at university - up from less than 5,000 in 2002, figures obtained from the Higher Education Statistics Agency by the Guardian show. The overwhelming majority started only a year early, at 17, but official documents suggest there are up to 100 university students under 16.

If we can't enroll them in universities, maybe we can train them to be parataxonomists.

Assiminea succinea takes a dip, but doesn't like it

The tiny Assiminea succinea is one of my favorite semi-terrestrial, coastal snail species. If there were a contest to select the cutest snail, I would vote for it without a 2nd thought.

The shell of this snail was about 3 mm long.
Photographed with an Olympus E-500 with a 35 mm Zuiko lens + 25-mm extension tube; 1/160 s, f14, ISO 200; light was from an Olympus FL-36 flash; both the camera & flash were hand-held.
Despite the fact that Assiminea succinea lives by the sea and is classified as a "sea shell", it doesn't like being in the sea. I was able to demonstrate this to my own satisfaction with a simple immersion* test last week when I was in Florida. The experimental set-up consisted of a small plastic container containing sea water into which a slanted platform was placed.


I placed each of the 2 "volunteers" I had one at a time on the platform just below the meniscus and then watched them while timing them. Both crawled out of the water in about 8 minutes. They were slow crawlers and the surface tension that they had to break thru may have hindered their movements a bit.

Here is one of the little guys struggling to get out of the water.


One nice thing about staying with relatives was that I had a bathroom to myself that I turned into a snail lab and photo studio for the duration of the 5 days we were there. In a hotel room, on the other hand, I would have hesitated to leave my specimens, live snails and equipment around during the day.

The 2nd post about A. succinea is here.

*Immersion is not to be confused with emersion.

The creature from my sister's garden

Keywords: Armadillidium vulgare, Isopoda, Oniscidea, introduced species, Canada

Last October when I was visiting my sister and her family in Montreal, I went out into their backyard one nite after a rain to check out the local creatures. I saw snails, an Oxychilus sp., and the isopod Porcellio spinicornis.

There was another isopod species, Armadillidium vulgare, which I photographed and took one specimen of. Subsequently, I realized that A. vulgare, an introduction from Europe, had not been recorded in Quebec before, although it is quite widespread in North America.

A one-page note announcing the new record coauthored by me and my isopod teachers Joan Jass and Barbara Klausmeier of the Milwaukee Public Museum just got published in the Spring 2008 issue of the Newsletter of the Biological Survey of Canada (Terrestrial Arthropods). The pdf copy of the newsletter is here. Our note is on page 13.

Armadillidium vulgare in my sister's garden.

Incidentally, this is my first isopod publication.

TSA surprise

When I picked up my suitcase at the National Airport at the end of our flight from Florida this afternoon, I noticed that the lock on the suitcase had changed places. So I suspected some funny business.

Sure enough, when I opened my suitcase at home, I found a thoughtful note left behind by the ever-vigilant folks at the Transportation Security Administration.

What could have looked unusual and suspicious to their keen eyes? My sandals? The bag of dirty laundry? The laptop?


Or, were they confused by the many small spiral objects that may have showed up on their screens?


Luckily, my snail shells survived the government scrutiny unscathed.

Otala lactea in Pass-a-Grille

The edible European land snail Otala lactea was introduced to Pass-a-Grille, the southern tip of an ex-island just outside of the Tampa Bay in Florida that is now connected to the mainland by a bridge. Yesterday, we found a bunch of them alongside a wall behind the beach in Pass-a-Grille.

The snails live on sand, which doesn't retain any water on the surface even in areas where the meager ground cover provides some shade. During dry weather both the juvenile and adult O. lactea aestivate on stems and blades of grass.


Later at a nearby restaurant, we noticed that the menu featured escargot. Perhaps, the chef has discovered the ideal solution to control the population of one non-native species.

Flying saucers explained

Our rental car parked by Dairy Rich.
During our trips back home from the beach here in Florida, a dumpy roadside eatery called Dairy Rich has become a mandatory stop. That's where we fulfill our daily recommended ice cream requirement. There are hardly ever other customers (I wonder why), but the usual "staff" of one young girl is quite pleasant.


While we were enjoying our ice cream today, I was reading their menu displayed on the outside wall. One item attracted my attention: Flying Saucer with the rather odd price of $1.51 each. I went over to the window and inquired about it.

Me: What's the flying saucer?
Girl: We don't make them anymore.
Me: What was it?
Girl (smiling): I have no idea.
(The guy in the back says something to her.)
Girl: Oh, it was like an ice cream sandwich.

I may ask about the frozen banana tomorrow.

Isopod blogging from Florida

Every animal phylum with terrestrial representatives seem to have a few species that have not moved very far from their ancestral homes. Their evolution stopped, at least for now, at the edge of the water; although they are terrestrial animals, they can't live very far from the oceans. And why should they? Beaches, mangrove forests, rocky coasts could be pretty good places to spend one's live at, if you ask me.

There are many terrestrial isopod species that live near the sea. Those are the species I don't get to find in Maryland. So, whenever I get a chance here in Florida, I am looking for isopods. Several species have turned up so far. Here is one that came from under some piles of seaweed at the high-tide mark at one of the beaches.

Here is another species from a different habitat. These were in leaf litter among the roots of a tree growing just a few meters away from a lagoon at a local park.


Species identifications will have to wait until I get back home.

Hermit crab blogging from Florida

The life lines of 2 hermit crabs intersected with ours at the beach today. My son found both. After they reluctantly posed for me, I returned them to the incoming tide.

If I am not mistaken, the one above was occupying a Melongena corona shell. The other one was a big, hairy, mean-looking guy (or a gal), but it would rather stay in the safety of its shell than come out and crawl across the sand. I believe the 10-cm long shell it had adopted was a tulip shell (Fasciolaria sp.).

Snail blogging from Florida

My son and I arrived in Tampa, Florida this afternoon for 5 days of fun and snailing. We were greeted by a rain storm that, luckily, ended a few hours later. So we went out for an early evening walk in the neighborhood to scout for snails.

The first species we saw was the extremely common Polygyra cereolus, a Florida native that has been distributed all over the place by human activities. Several of them were crawling on the undersides of pieces of bark that had falled from palm trees.

Later on a sidewalk, several individuals of Bradybaena similaris crossed our path. They too are widespread, but unlike the former species, they are not native to the U.S. and were introduced from Asia.


We will spend most of the day at the beach tomorrow. Hopefully, there will be opportunities to collect some good data.

Sand castles raised during emersion will be razed during immersion

Immersion and emersion are antonyms of each other and at the same time, they have the same pronunciation. The above links are to the Free Dictionary, which uses the same pronunciation symbols for both words, whereas Merriam-Webster uses slightly different symbols for immersion and emersion, but when I played their pronunciations to my wife (a native English speaker), she couldn't hear a difference. She also made the valid point that even if there were a slight difference between their pronunciations, one wouldn't notice it during a normal, fast-paced conversation. Tim Pearce, on the other hand, told me in an e-mail that he pronounces them differently: immersion with a short "i" sound and emersion with a long "e" sound. Next time I see him, I have to ask him to pronounce them.

Tim also mentioned raise and raze, another pair of words that have the same pronunciation but opposite meanings.

Scrabulous game enters 3rd week

I think. Or it may have been 4 weeks since Deniz and I started this game on Facebook. What's the rush, right?

Deniz is leading 140 to 86. The last word I put down was anode. It's her turn.

Crepidula: gender bending gastropods

"The gastropods exhibit nearly every possible modification of sexuality."
R. Tucker Abbott American Seashells (1954)

The marine snails with limpet-like shells in the genera Crepidula, Crucibulum and Calyptraea make up the family Calpytraeidae. They are all protandric hermaphrodites: young snails are males that may grow larger and change into females.

And that isn't the only unconformity the calpytraeids are known for. They also spend their lives in tall stacks with the females on the bottom followed by piles of males on top of them patiently waiting for their turn to mate and then change into females to mate again. How is that for kinky sex?

"Girls will be boys and boys will be girls.
It's a mixed up, muddled up, shook up world, except for Lola."
Kinks, Lola

The picture above shows the intertidal snail Ilyanassa obsoleta from Chincoteague with a couple of Crepidula on its back. Presumably the larger Crepidula on the bottom was a female, while the one on top a male. The drawing below is a simplified rendition of the sex life of Crepidula.


From Mark D. Bertness, Atlantic Shorelines-Natural History and Ecology, 2007.
That the calpytraeids are gastropods, that is, snails, is hard to tell without a close scrutiny. Their shells have all but lost the characteristics spires of ordinary snail shells. It would not be possible for ordinary gastropods to pile up on top of each other for more than 2 or 3 snails before they turn into a rather unstable tower. So I suspect the flattened shapes of the shells of the calpytraeids must have coevolved with their sexual habits.

If humans went extinct, would it be an improvement?

The first science fiction story to be published in the journal Nature was the late Arthur C. Clarke's Improving the neighbourhood.

Down among the stuffed beasts

In the back rooms and top floors of natural history museums, hidden from the public eyes, there are often objects and artifacts that are waiting for their turns to go on display.

Usually, stuffed animals, in life-like postures, but covered in dust, are a dime a dozen.


I am always distressed by the sight of a mammal or a bird that was taken from the wild, killed and then stuffed for the sole purpose of satisfying morbid human curiosities and obsessions. To me, observing a live animal, a product of nature doing what it has evolved to do, is infinitely more satisfying than looking at a taxidermist’s creation.


What about keeping animals in zoos? Some organizations, such as the Born Free Foundation, is campaigning to “phase out” zoos throughout the world. I haven’t given much thought to the idea, but it is something certainly worth considering.

Cloning echinoderm larvae: isn’t there strength in numbers?

Vaughn , D., Strathmann, R.R. (2008). Predators Induce Cloning in Echinoderm Larvae. Science, 319(5869), 1503-1503.

This one of those "Brevia" papers in Science that present important research results with very little data that sometimes leave the readers wondering how the claims made in the paper could have been supported.

When Vaughn and Strathmann exposed 4-day-old sand dollar (Dendraster excentricus) larvae to mucus from fish, their potential predators, the larvae started cloning themselves within 24 hours. For example, buds formed on the surfaces of larvae, which were subsequently released as independent individuals. In other words, one larva became two smaller ones. The implication here is that both larvae had the potential to grow to be adults.

Vaughn and Strathmann emphasize the reduction in size of the cloning larvae as the possible reason why cloning is advantageous when there is a predator lurking around: "We hypothesize that reduced size in clones decreases detection and selection by visual predators and may reduce signals to some nonvisual planktonic predators." I would like to see how the sizes of the clones compare against the size distribution of the controls. Are they significantly smaller than the controls?

What about the other possible advantages of cloning? I can think of 3 that arise not from the shrinking of the larvae but simply from the increase in their numbers.

1. A larva increases its own chances of long-term survival simply by making a clone of itself. If one gets eaten, there will still be the other one that may become an adult. This is true regardless of the added protection being small may offer against predators.

2. Having an "extra" copy of one's self, increases the chances of dispersal of, well, one's self to a place where there may be no predators. (These are planktonic larvae that are carried around by the waves and currents.)

3. The increased numbers of the larvae may even create a "schooling" effect to provide visual protection from predators. This would, of course, work only if the larvae were not too dispersed in the ocean to begin with.

I am looking forward to a longer paper by the same authors that will hopefully present more data and a more detailed discussion.

Science is fun

"There's no importance whatsoever. I'm just doing it for the fun of it."
Richard Feynman explaining to Hans Bethe the reason why he started working on the physics problem that later developed into the project that eventually earned him a Nobel Prize.*

The dictum that science is and should basically be a fun activity is not stressed enough by scientists, especially in scientific publications. The lighter side of doing scientific research is especially obvious to those of us who do field work. Yet scientific reports are often chastised for being rather dull and for not revealing the general feeling of enjoyment the scientists get from doing research.

Earlier today I was reading an almost 40-year old paper** on the sand-beach isopod Tylos punctatus. It was a pleasant surprise to come across a rare admission by scientists in a serious scientific paper that field work is actually a fun activity. Here is the very last paragraph of the cited paper (underlining mine):

T. punctatus is enormously abundant on El Estero Beach: up to 23,000/m² when buried in the sand. Its great abundance, its simple life history, and its simple and pleasant habitat, all make it an excellent animal for research into population dynamics. We cannot now do this research ourselves, but we hope someone else will. It would be fun.

Why don’t we admit openly and announce to the general public more frequently in our writings that scientific research is indeed a fun activity?


*There are slightly different versions of this quote in Feynman’s own accounts of it, but the basic idea is the same. For example, compare the version here, which is from Feynman, R. (1985), Surely you're joking Mr. Feynman, with that in Feynman & Sykes (1994), No Ordinary Genius.

**W. M. Hamner; Michael Smyth; E. D. Mulford, Jr. (1969). The Behavior and Life History of a Sand-Beach Isopod, Tylos Punctatus. Ecology, 50:442-453.

Bootleg transactions of the 10th MAM meeting

The 10th meeting of the Mid-Atlantic Malacologists was yesterday at the Delaware Museum of Natural History (DMNH) in Wilmington, Delaware. With about 40 attendees, 13 talks and 2 posters, this was probably the largest MAM meeting so far. And as usual, it was a lot of fun.

Here are the speakers, in the order they spoke, and the not-more-than-two sentence summaries of their talks.

Marla Coppolino (Southern Illinois University): Abundance and diversity of the land snails of southern Illinois. Her results indicate that there is a weak positive correlation between habitat diversity and snail species diversity.

Gina Meletakos (Towsen University): DNA barcoding of the land snail genus Stenotrema.

Colleen Sinclair (Towsen University): The lack of genetic differentiation among the colonies of the land snail Ventridens ligera along the Potomac Gorge.

Paula Mikkelsen (Paleontological Research Institution, Ithaca, NY): BivAToL project funded by the National Science Foundation to reconstruct the phylogenetic relationships of the Bivalvia.

Aydin Örstan (Carnegie Museum of Natural History): Annual generation cycle of the land snail Oxyloma retusa.

Bill Fenzan (Norfolk, VA): When E.J. Petuch described Conus lightbourni in 1986, the holotype was to have been sent to the DMNH, but the museum never received it. More than 20 years later, Bill Fenzan identified the lost holotype in the collection of a shell dealer and was able to obtain it for the DMNH.

Robert Robertson (Academy of Natural Sciences, Philadelphia): Studies on the larval development of the gastropod family Pyramidellidae. They are ecto-parasites of many marine animals, including tube worms and oysters.

Ilya Temkin (American Museum of Natural History, New York): The story of Museum Boltenianum, a sale catalog from 1798 that was published by P.F. Röding to sell the mollusk shells from the collection of J.F. Bolten and also to publicize the latter's taxonomic system.

Gerald Lang (Carnegie Museum of Natural History): Color variations of unionid shells and possible evidence for beaver predation on freshwater mussels.

Valves of Lampsilis ovata that were forced open by a predator. Did a "vegetarian" beaver do it? (From the collection of Gerald Lang; published here with his permission.)

Susan Hewitt (New York): Marine mollusks of the island of Nevis in the West Indies. There are 500 species of them and she is still counting.

Megan Paustian (University of Maryland): Resource competition (or the lack thereof) between native and non-native slugs in Maryland forests.

Charlie Sturm (Carnegie Museum of Natural History): The ongoing search at the CMNH for the syntypes of the many species of the freshwater clams of the family Sphaeriidae that Victor Sterki described 100 years ago.

Liz Shea (DMNH): Squids of the Sable Island Gully Marine Protected Area off Canada. What are the sperm and bottlenose whales feeding on?

Posters:

Tim Pearce (Carnegie Museum of Natural History): Influence of glacial history on the distribution of land snails on the islands of Lake Michigan.

Clement Counts (Salisbury University): Chronology of the invasion of the U.S. waters by the bivalve Corbicula fluminea.

I will take this opportunity to thank again to Liz Shea, the curator of mollusks at the DMNH and Leslie Skibinski, the collection manager, for organizing this wonderful meeting and also for providing access to the collections during the lunch break and after the meeting. I am already looking forward to next year's meeting.


Most of the meeting attendees outside the Delaware Museum of Natural History.

Sleeping Haplotrema concavum wakes up

Around noon today the dormant Haplotrema concavum that I first saw on 20 December 2007 (85 days ago) was still hibernating in its little hole in the soil. The previous posts about this particular snail are here and here and here.

I wanted to take pictures of the snail, but I was afraid that if I waited too long, it would wake up on its own and crawl away, so I decided it was time for me to wake it up. I brought it home in a little container and when I took it out about a half an hour later, the snail had already moved closer to the aperture (you can see in the pictures in the earlier posts that during hibernation, the snail's body was 1/4 whorl behind the aperture).

Here is a set of pictures of showing how H. concavum came out of its shell. About 2 minutes elapsed between the first and the last picture. Compare it with the pictures of how Pomatias elegans comes out of its shell in this post. In both snails the foot comes out first, followed by the head. In other words, the overall sequence is the same in both snails even though from an evolutionary view point they are quite distant from each other.

In the case of P. elegans, the foot has to come out first to move the operculum, which is attached to the foot, out of the way. But why does H. concavum, which doesn't have an operculum, have to put its foot out first? I can think of 2 answers. First, it wouldn't be safe for a snail to put its head out first, because if a waiting predator attacked it, the snail could get injured on its head where all the vital organs are, whereas an injury at the tip of the foot would be easier to deal with. Second, the snails without opercula are stuck with this sequence because their musculature and body plans evolved from ancestors that had opercula.

Here is the fully revived H. concavum.


Haplotrema concavum is a carnivore and this one hasn't eaten anything since December. I have some potential prey for it. If I can photograph it doing what it does best, eat another snail, I will post those pictures next week.

Bag o' books

I mentioned in this post that one of my favorite bookstores is the NHBS Environment Bookstore over in the UK across the Atlantic. About a month ago an e-mail from them announced a huge sale. Despite the shipping cost and despite the depressingly low value of the dollar these days, I calculated that NHBS's total would still be less than what I would pay Amazon in the U.S. for the same books, despite the fact that Amazon doesn't charge for shipping for orders above $25; the NHBS's sale prices were that low. I already have a backlog of books to read, but how can I resist such a deal?

So I ordered 3 books: A History of the Ecosystem Concept in Ecology by F.B. Golley, The Insects: An Outline of Entomology by P.J. Gullan & P.S. Cranston and John A. Endler's classic Natural Selection in the Wild.


The books came today in a sealed box that was inside a blue bag large enough to smuggle 3 cats across the U.S.-Canadian border. Now I am wondering what to do with the bag.

Polynesian rats of Mokapu: is there a statute of limitations for introduced species?

I am all for the prevention of the introductions of species to areas where they are not native and for the elimination of those that were introduced recently, provided that the latter process can be accomplished without harming the coexisting native wildlife*.

A recent post over at Raising Islands--Hawai'i science and environment was about the eradication of the non-native Polynesian rat, Rattus exulans, on a small island of the Hawaiian Archipelago. Detailed information is given in the Final Environmental Assessment (EA) prepared by the U.S. Fish and Wildlife Service and Hawai'i Department of Land and Natural Resources.

Mokapu Island. Picture from the EA.
The subject island is Mokapu, an uninhabited 4-hectare (10-acre) piece of rock with steep sides 1 kilometer off the northern coast of the much larger Moloka'i Island. The justification for the eradication program was the known propensity of the Polynesian rat to prey on ground-nesting seabirds, although as far as I can tell from the speculative information in the EA (see section 1.2.4), it was never demonstrated if such predation actually took place on Mokapu and if it did whether it was threatening the nesting bird populations.

The eradication was accomplished by dropping food pellets containing a rodenticide called diphacinone from helicopters. I will leave aside the thorny issue of introducing a poison into the environment to save a habitat and the wildlife that live there; the EA discusses the potential effects of diphacinone in the environment.

Reading about this raised more of a philosophical question in my mind: how long does an introduced species have to exist continuously at a location before it can be considered “native”? The EA mentions that the Polynesian rat was introduced to the Hawaiian Archipelago about 1500 years ago. By now, the rats are certainly "naturalized" members of the Hawaiian fauna and they are there to stay. And if the native Hawaiian species and the rats have coexisted for so long, how likely is it that the rat could have recently turned into a menace to the native wildlife? I don’t think that is a likely scenario at all. The EA mentions this issue only in passing:

Of the four rodent species, the Polynesian rat arrived with the early Polynesian settlers and is found throughout the main Hawaiian Islands (Hess et al. in press, Tomich 1986). Because the introduction of rats to Hawai'i perhaps as early as 1,500 years ago, its major influences on the native plants and animals are assumed to have occurred long before Europeans arrived at the archipelago.

During so many years of mutual struggle, one may even expect natural selection to have given the native wildlife some ability to resist the rats. Of course, it is possible that the rats invaded Mokapu much recently and therefore, they may still be in the stage where they would be most harmful to the native wildlife of Mokapu. However, according to the EA, people are not known to visit Mokapu, although fishing is done around it. It is, therefore, not clear how the rats ever reached the island. One possible dispersion route is via logs and other debris carried by waves and currents from nearby larger islands. If that has been the most likely way of transfer, then the rats may have reached Mokapu a long time ago.

There may be a deeper issue here. Are we turning the rat into a scapegoat to bear the blame of what everyone darn well knows to be the real cause of extinctions: habitat loss to never-ending development?


*I also support eliminations of goats, those destructive rascals.

I hear the snails talking to me!

Deniz the Niece revealed that she hears voices. That’s no reason to be alarmed though, for those are the voices of the characters in the novel she’s been writing. It’s all part of creative thinking.

Sometimes I hear or read something – a word, a phrase, a lyric – and it starts the ball rolling, whether action, dialogue or monologue, and I have to write it *now* or I’ll lose it. These are the ideas that come fully-formed, often at the beginning of a new story, and are generally the roughest stuff – need a lot of hacking through in the editing process.

Interestingly, she is describing how I frequently come up with ideas when I am intensely working on a scientific manuscript. It usually happens when I am on a walk. I start thinking about the parts of the manuscript that still need to be written or revised and about the snails that are the usual “characters” of my manuscripts. Then, a train of thought, so to speak, suddenly appears, as if from out of a tunnel; this is followed by sentences to be added to the manuscript forming in my mind. If I happen to have a pen and a piece of paper on me, I may even write them down so as not to forget them.

And, yes, although at first they sound perfectly fine, these spontaneous creations must be edited, rewritten, revised, rewritten...many times. And occasionally, upon further rumination, they even get chucked out of the manuscript.

I guess writers’ minds works the same way regardless of what it is that they may be writing, whether it is fiction or nonfiction. The process of creativity in literature and science must have a lot in common.

Boxcar graffiti LVIII & LVIX & LX

10th meeting of the Mid-Atlantic Malacologists will be this Saturday

The 10th almost-annual meeting of the Mid-Atlantic Malacologists will take place on Saturday 15 March 2008 at the Delaware Museum of Natural History in Wilmington, Delaware.

MID-ATLANTIC MALACOLOGISTS (MAM)
Tenth almost-annual meeting

Saturday 15 March 2008 10:00 am
Delaware Museum of Natural History
4840 Kennett Pike, Box 3937, Wilmington, DE 19807, U.S.A.
Host: Dr. Liz Shea, Curator of Mollusks

The tenth almost-annual meeting of the Mid-Atlantic Malacologists will occur Saturday 15 March 2008 at the Delaware Museum of Natural History (DMNH) in Wilmington, Delaware. This one-day gathering is designed to facilitate contact among professional, amateur, and student malacologists who are interested in any aspect of molluscan biology. There are no dues, officers, abstracts, or publications. Meeting and parking are free of charge. Participants are encouraged to present and discuss data, compare notes on methods and problems, and catch up with colleagues and friends. Presentations (15 minutes max.) are very informal and cover topics as diverse as current research, trip reports, and collection issues.

For additional information or to inform Dr. Liz Shea, Curator of Mollusks at DMNH, that you will attend and/or give a talk, please contact her at esheaATdelmnh.org.

I am planning to go and talk about my research with Oxyloma retusa.

The pleasure of finding a snail shell

Many years ago I watched a program on PBS about the physicist Richard Feynman*. I liked Feynman's ideas so much that I ordered a copy of the transcript, which I still have. This is what Feynman said about the Nobel prize he had won:

I don't see that it makes any point that someone in the Swedish Academy decides that his [someone's] work is noble enough to receive a prize. I've already got the prize. The prize is the pleasure of finding the thing out, the kick in the discovery, the observation of other people using it. Those are the real things, the honours are unreal to me.

Earlier this afternoon, my son and I went on a walk in the woods near our house. I had my eyes open for trees with holes in their trunks, for those are the places I've often found snails. Presumably, the tree holes provide both food, perhaps in the form of fungi growing on rotting wood, and shelter from the weather. Near the end of our walk we were at an area where I had not been before. A tree that had a large cavity at its base attracted my attention. I went over and took a look at it. Sure enough, there was an old, bleached Anguispira fergusoni shell just outside the cavity.


I have hundreds of shells of A. fergusoni, most in better condition than this one, from these woods. But finding this one on a cold winter day gave me a special pleasure, because I had never encountered that species at that particular location before. It extends the range of A. fergusoni that is known to me by only about 150 m or so. Three hundred years ago, when an unbroken forest covered this region of North America, this would have been an insignificant find, but today when even the "protected" wildlife habitats are under constant threat of destruction, it is somewhat reassuring to know that if what is over there is destroyed by some new road or a sewer project, a few snails may still survive over here.

Soon after we returned home, I thought of Feynman's ideas. Although I couldn't recall his exact words, the general idea of the pleasure of discovering something had etched itself in my mind.


*It was the Nova episode #1002 titled The pleasure of finding things out that aired on PBS on 25 January 1983. I was still in graduate school at that time.

A Sunday story: Father, Son and the Holy Donkey

During their formative years monotheistic religions appropriated and conveniently adopted, with or without suitable modifications, many pagan customs, traditions and deities. New saints and otherwise holy men (and women) have continued to be created out of figments of imagination, hazy scraps of ancient legends or from outright fakers (for a recent example, see this post). Unfortunately, the "true" believers are too brainwashed to see thru the fake, yet thin, veil of authenticity what is actually hiding behind the purported holiness.

In his memoirs, My Life as an Explorer (1925), Sven Anders Hedin mentions the abundance of saints' graves around the city of Kashgar in 1890. He also relays this self-parodying story that was apparently popular at that time among the local Moslems.

A sheik used to teach the Koran to his disciples at a saint's grave outside Kashgar. One day, one of the pupils came to the sheik and said: "Father, give me money and food, so that I may go out into the world and try my luck." The sheik answered: "I have nothing else to give you but a donkey. Take it, and may Allah bless your journey."

So the youth took the donkey and left. He wandered around for a while and one day when he was crossing a desert, the donkey died. The youth buried the donkey and then sat down on the grave to cry. Just then, a caravan of some rich merchants happened to be passing by. When the merchants inquired about the reason for the youth's sorrow, he told them that he had lost his "faithful travelling-companion." The merchants were so touched by this that in the due course of time they had a magnificent mausoleum erected at the spot.

The tale of the new saint's grave travelled fast, and pilgrims from far and near thronged there to perform their devotions. After many years, the old sheik from Kashgar also went there. Astonished at finding his former pupil a sheik at so prominent a saint's grave, he asked: "Tell me, in confidence, who is the saint that rests under this cupola?" The pupil whispered: "It is only the donkey you gave me. Now you tell me who was the saint that reposed where you used to teach me?" To which the old sheik replied: "It was the father of your donkey."

How snails mate: Oxyloma retusa

Keywords: Succineidae, gastropod, pulmonata, mating, sex, evolution, shell coiling, dextral

Snail shells come in 2 basic shapes: tall or wide. Shell shape is usually expressed as the ratio of shell height to shell diameter; therefore, tall shells are taller than wide, while wide shells are wider than tall. This fundamental dichotomy and the scarcity of shells that are about as tall as they are wide was first pointed out by Cain (1977).

It so happens that the mating positions of terrestrial pulmonate snails also fall in 2 groups: face-to-face and shell-mounting. Interestingly, which position a given species mates in depends, with exceptions, on its shell shape: most species with tall shells mate by shell mounting, while most species with wide shells mate in the face-to-face position. Evolution by itself is an exciting enough research area and when you add sex to it, you can imagine the simulation, arousal of curiosity and the gradual building up of intellectual tension only released by occasional climaxes provided by the publication of a landmark paper. Research on the evolutionary origins and implications of mating positions of snails is no exception; for more information, I will refer the readers to Asami et al. (1998), Davison et al. (2005) and Davison & Mordan (2007).

The almost-amphibious land snail Oxyloma retusa (family Succineidae), which previously was the subject of this post and this post, has a tall shell and expectedly, mates by shell-mounting. Here are 2 individuals mating.

The snail on the right is on the shell of the slightly lower snail on the left and has its head slightly twisted. The twisting of the head is apparently necessary, because these are both dextral individuals and so, their genital openings are on the right sides of their heads. Only by twisting its head can the snail on top bring its genital opening next to that of the lower snail.

A sinistral snail, on the other hand, would have its genital opening on the left side of its head. Could it still mate with a dextral individual of its own species? Yes, if they had tall shells. According to Asami et al. (1998), 2 individuals with tall shells and with opposite shell coiling could mate "with small behavioral adjustments." In the case of O. retusa, for example, the necessary behavioral adjustment would be that if the snail on top were sinistral, it wouldn’t need to twist its head. Therefore, an aberrant individual with a tall sinistral shell among tall-shelled dextral conspecifics is more likely to be able to mate and leave offspring than one with a wide sinistral shell among wide-shelled dextral conspecifics. The evolutionary result of this is that sinistral species or closely related species with oppositely coiled shells are more common among tall-shelled lineages than among wide-shelled ones.

Pascal over at Research at a snail's pace has some information on the reproduction of another succined, Succinea ovalis.


Asami, T., Cowie, R.H. & Ohbayashi, K. (1998): Evolution of mirror images by sexually asymmetric mating behavior in hermaphroditic snails. American Naturalist 152:225-236.

Davison, A., Wade, C.M., Mordan, P.B. & Chiba, S. (2005): Sex and darts in slugs and snails (Mollusca: Gastropoda: Stylommatophora). Journal of Zoology 267:329-338.

Davison, A. & Mordan, P. (2007): A literature database on the mating behavior of stylommatophoran land snails and slugs. American Malacological Bulletin 23:173-181.

Cain, A.J. 1977. Variation in the spire index of some coiled gastropod shells, and its evolutionary significance. Philosophical Transactions of the Royal Society, London 277:377-428.

How to help searchers find what they are looking for

Yesterday someone who was searching the Internet using the keywords "barnacle mollusk symbiosis" found this post, which is about barnacles, but mentioned mollusks only as one of the many different substrates a barnacle can grow on, and missed this one and this one, both of which would undoubtedly have been much more relevant.

Ever since then, I have been monitoring the keyword activity lists created by StatCounter to see how closely the searchers' keywords come to the posts they end up with. Often, they are right on the target or find a post the topic of which appears to be close enough to their inquiry. For example, 2 people using the search phrases "what are shells made of" and "composition of snail shell" both found this post, a perfect match. Likewise, someone else with the phrase "king married sister" found this post; again, I think, a pretty good match, although it is hard to be sure without knowing what exactly the person who was doing the search had in mind.

On the other hand, the person who searched with the phrase "how to cook moon snails, " which are marine, only got this recipe for cooking land snails. But I suppose one could adopt a recipe that works for one type of snail to cook another.

The person who used the words "snails food" was less fortunate and came to this post about a snapping turtle, which is not something snails normally consume, but for some reason missed this one, which is indeed about what a snail may eat.

It is interesting to note that some of the search phrases were the exact matches of the titles of my posts. For example, "the last tree" and "is it a boy or a girl". However, I have no idea what exactly the searchers in those cases were looking for and I doubt the person who used the latter phrase wanted to know how to sex an isopod, which happened to be the subject of my post with the same title.

I can recommend 2 improvements in blog posts to help searchers find the information they are after:

1. Connect relevant posts to each other with links to redirect a person to another post that may be more relevant or may provide further information.

2. Add relevant keywords to posts to increase their chances of getting found by search engines when the keywords or phrases used by searchers contain associated words that may not be in the actual text of a post. For example, if I had added the keyword "mollusk" to at least one of my linked posts about barnacles living on snail shells, then the searcher who used the phrase "barnacle mollusk symbiosis" would probably have found them.

I already routinely link my related posts to each other. And I will now start adding keywords at the bottom of my posts.

An evolutionary view from the shore of a microcosm

To better make sense of a book* I've been reading, today I searched for Stephen A. Forbes’s classic paper from 1887, The Lake as a Microcosm. Luckily, a copy was available at the Early Classics in Biogeography, Distribution, and Diversity Studies: To 1950 archive.

Forbes’s insight of the intricate evolutionary interdependencies of the species in lakes was impressive; his clear explanation of the complexity, within just one short paragraph, was even more so.

If one wishes to become acquainted with the black bass, for example, he will learn but little if he limits himself to that species. He must evidently study also the species upon which it depends for its existence, and the various conditions upon which these depend. He must likewise study the species with which it comes in competition, and the entire system of conditions affecting their prosperity, and by the time he has studied all these sufficiently he will find that he has run through the whole complicated mechanism of the aquatic life of the locality, both animal and vegetable, of which his species forms but a single element.

A hundred years before Geerat Vermeij came out with Evolution & Escalation (Princeton University Press, 1987), Forbes had already hit upon the idea of a perennial evolutionary arms race between predators and their prey.

Every animal within these bounds has its enemies, and Nature seems to have taxed her skill and ingenuity to the utmost to furnish these enemies with contrivances for the destruction of their prey in myriads. For every defensive device with which she has armed an animal, she has invented a still more effective apparatus of destruction, and bestowed it upon some foe, thus striving with unending pertinacity, to outwit herself, and yet life does not perish in the lake, nor even oscillate to any considerable degree; but on the contrary the little community secluded here is as prosperous as if its state were one of profound and perpetual peace.

Is there a battle of evolution beneath the calm surface of this microcosm?
And what is the simple explanation behind all of this? Natural selection, of course.

We thus see that there is really a close community of interest between these two seemingly deadly foes. And next we note that this common interest is promoted by the process of natural selection; for it is the great office of this process to eliminate the unfit.

What Forbes referred to as the elimination of the unfit is now known as stabilizing selection, which operates by making it more likely for the individuals with extreme traits to perish before reproducing.


*William H. Drury, Chance and Change, 1998. Review is forthcoming.

On the destructive roots of Christianity

Were the fanatic Christian iconoclasts responsible for all those headless statues that now clutter up the museums? Eberhard Sauer, a reader in classical archaeology at the University of Edinburgh, attempts to answer that question in The Archaeology of Religious Hatred (Tempus, 2003).

The required detective work is, however, no easy task when the only clues available in most cases are nothing more than some headless pagan gods or mutilated murals. How can we know that it wasn’t an enemy soldier seeking revenge, or an earthquake or a simple accident that was the real culprit? According to Sauer, the presence of any of the following 5 pieces of evidence is enough to suspect Christian zealots and "saints".

1 exceptionally laborious and thorough modes of destruction without any obvious practical purpose like re-use of stone,
2 cases where pagan images appear to have [been] targeted, but other artwork spared,
3 cases where naked deities were more thoroughly destroyed than their modestly dressed counterparts,
4 temples in which items of value, notably coins or other metal
items, were deliberately left behind, and, of course,
5 iconoclasm in temples which soon thereafter were consecrated
as churches or built over by churches.

Sauer discusses several examples of vandalized pagan temples, mostly in Europe, but also in the Middle East and Egypt, goes over the available evidence and argues that in many cases the perpetrators were Christians.


Who dunit? Gods that were being restored at Claros in western Turkey in August 2000.
The book provides quite a bit of information on Mithraism, a relatively short lived religion that was popular among the subjects of the Roman Empire, and about which I knew nothing previously. According to Sauer, some common elements Mithraism had with the then emerging Christianity made its temples a frequent target of Christian iconoclasts.

It is precisely because Christianity did not have a monopoly on the promise of salvation and heavenly life after death that Eastern mystery cults, notably those of Isis and Mithras, were serious competition, even though the exclusion of women put Mithraism at a major competitive disadvantage.

Not every case Sauer reviews as a purported example of destructive Christian iconoclasm is fully convincing; in some instances, the evidence is not entirely supportive and his conclusions are speculative and controversial. For example, the destruction of the Mithras temple at Mühlthal in Bavaria was attributed, by its excavator, possibly to looters seeking treasure despite the fact that a large number of coins had been left behind. Sauer, however, thinks that Christians were indeed responsible for the act, because "[i]t makes infinitely more sense to argue that the decision to leave money behind was borne out of religious conviction, the fear of contamination with cursed votive objects, and the fear of divine punishment."

However, treasure-seeking, which must have been a strong and perennial driving force for the vandalism of many religious sites, cannot be easily dismissed. Charles Fellows noted in his Travels and Researches in Asia Minor the impressions he had of the Anatolian peasants' destructive preoccupation with hidden treasures in Anatolia in 1840. (Incidentally, more than 160 years later, the rural mentality towards antiquities is sadly still the same in Turkey.)

My guide kept earnestly begging that I would point out the stones in which he should find gold, thinking that I knew from my books where it was to be met with. The people had spent much time and trouble in cutting pedestals in pieces, imagining from their having inscriptions that they contained treasure. They have in several instances been fortunate, and I saw a split stone which from its form had probably been a kind of altar; into this they had cut, and, concealed in a hollow in the centre, they had found, they said, much gold money.

Overall, this is an interesting book, but it is a little difficult to read, because of Sauer's somewhat dense style. Most of the book is general enough for a reader like me with no relevant background to follow, but towards the end, Sauer veers into what appears to be a long-running dispute between academic fractions and the previously more informative style of the book turns into one of "he said that and I said this." Fortunately, however, those parts are short and can be skipped without missing out much.

$30 a month for an online dictionary? Get serious, Oxford

The Oxford English Dictionary thinks their online version is worth the "low" monthly rate of $29.95. If that was an annual fee, I would think about it, but still turn them down. I don't see the point of feeding them so much money every month when there are all those free dictionaries. What could they possibly offer that the rest can't?

Merriam-Webster
Free Dictionary
Dictionary.com

There are probably others.

Bufo viridis under a rock

It's been almost 10 months since I mentioned in this post that I was going to write about this particular toad. Well, it's better late than never.

I found this Bufo viridis (also known as Epidalea viridis or the European Green Toad) last May in southwestern Turkey. It was under a large rock that I had lifted up while searching for snails. I didn't measure it, but wrote in my notebook that it was about 7-8 cm long.

We were on a mountain at an altitude of about 1800 mm. That area gets a lot of snow in the winter. In fact, when we were there in the beginning of May, there were still patches of snow on the higher slopes. In the picture below, you can see yours truly standing next to one such patch of snow that had by then turned into a sheet of ice. And yes, it was warm enough to wear a T-shirt.


As for the toad, it survives the harsh winter thanks to the abundant rocks that cover the surface. Its hypolithic hiding spot protects it from the snow, the ice, the cold winds and the sun. The underside of the rock must also be safe haven from its predators. We can say that the generations of B. viridis that live there have adapted themselves to the terrain.

Not bad

Hot and sweet.

Sleeping Haplotrema - update

The dormant Haplotrema concavum that I found on 20 December 2007 (73 days ago) was still hibernating this afternoon. The previous posts about this particular snail are here and here.

Tomorrow and Tuesday are predicted to be unusually warm. If the warming trend continues and if the snail is still there next weekend, I may attempt to revive it then.