SNAIL'S TALES

Archaeo+Malacology Group Newsletter No. 20

2012-01-17T21:45:00.000-05:00

The AMG Newsletter No. 20 is available here.

This issue starts off with yet another report on the land snail Papillifera papillaris. This time, Anette Rosenbauer is reporting it for the 1st time from Germany. The species, a native of Italy, was found in some stone-working yards.

There are also several articles by Henk Mienis about various mollusk finds at archaeological sites in Israel. In one of them, Mienis reports a mysterious accumulation of the shells of the marine snail Columbella rustica at a ruin.

In addition, there are the usual book reviews, lists of recently published relevant articles and the announcements of upcoming meetings.

Sleeping Cepaea nemoralis

2012-01-08T20:33:00.000-05:00

Yesterday I returned to my Cepaea nemoralis survey grounds near Frederick, MD to check up on the snails after an almost 2-year break.

I encountered several dormant snails partially buried in the damp soil. Obviously, neither the dampness nor the unseasonably warm weather (air temperatures were well above 10°C) were enough to wake them up.

Two previous posts about dormant Cepaea nemoralis were here and here.

When barnacles were mollusks

2011-12-29T18:14:00.000-05:00

This brightly colored picture of the gooseneck barnacle (Lepas anatifera) is from Edward Donovan's The Natural History of British Shells published in 1799.

Back then, and until the 1830s, barnacles were grouped together with mollusks, simply because they had shells as do most frequently encountered mollusks. Barnacles are actually arthropods, because they have jointed appendages like insects and their relatives. This post was about a barnacle on a snail shell.

Here is the title page of Donovan's book. It is available on Google Books.

Old Discus ruderatus

2011-12-19T21:59:00.004-05:00

As part of an ongoing study, which is almost finished, I've been measuring shells of several species of Discus. Among the species included in the study is the European Discus ruderatus. Here are the labels of 2 old lots from the Carnegie Museum of Natural History in Pittsburgh.

The oldest date I can make out on the labels is 7/30/01; undoubtedly, that was 1901. And the stated location "Klausenberg, Transylvania, Hungary" was presumably the city of Cluj in Romania.

The 2nd lot was collected in Grisons, a canton in Switzerland, in August 1852.

The previous post in this series was about Discus rotundatus.

When taxonomy was much simpler

2011-12-14T18:49:00.000-05:00

An excerpt from the entry for "Limax" in the 3rd edition of the Encyclopaedia Britannica published in 1797:

LIMAX, the Slug, or Naked Snail; a genus of insects belonging to the order of vermes mollusca...There are eight species, distinguished entirely by their colour; as the black slug, the white slug, the reddish slug, the ash-coloured slug, &c.

Observations of Deroceras laeve

2011-12-07T22:09:00.000-05:00

One highlight of tonight's malacology-related activities at home was the filming of 3 individuals of the slug Deroceras laeve while they were having their meals.

The slugs, who had been starving for several days, were on a glass plate that I had coated with corn starch. They seemed to really enjoy the starchy meal. Here is a frame from a film footage of one of the slugs taken thru the glass and the starch layer.

The arrow #1 is pointing to the jaw, while the arrow #2 is, I believe, to the tip of the radula that the slug was using to scrape the starch off the glass.

Morphological scaling in snails

2011-11-24T19:24:00.000-05:00

Here is the relation between shell volume, foot sole area and shell length for an intertidal snail.

In juveniles the foot is already shorter than the shell. During ontogeny the shell grows faster than the foot and so in adult snails the foot ends up being even shorter relative to the shell.

Note how much the rate of growth of the sole area lags behind the rate of growth of the shell volume. This is because volume is proportional to the cube of one or more linear dimensions, while area is proportional to the square of linear dimensions.

The interplay of volume and surface area and the resulting scaling effects underlie many evolutionary processes. For example, one reason why the smallest animals are all aquatic is that they lose their water content very quickly outside of the water, because their surface areas are very large relative to their volumes. At the opposite end of the range, the inner surfaces of the lungs of the largest animals always have convoluted morphologies, because the area of a flat surface would not be enough to satisfy the gas exchange requirements of the relatively much larger volume of the animal itself.

In the case of the subject snail, the consequence of this scaling effect is somewhat more mundane. When its shell gets too large relative to the foot, the snail can't lift the shell up anymore; it simply drags it behind its tail. In an earlier post, I discussed how this happens in the land snail Euxina circumdata.

This subject has had me preoccupied during most of my waking hours for the last month or so. In fact, I even lost sleep thinking over it one night. But finally, I am beginning to fit all the available pieces of the puzzle together.

Jaws of a different kind

2011-11-13T22:05:00.000-05:00

One of the many live snails I photographed last June when I was in Turkey was this juvenile of the species formerly known as Helix aspersa. After the photo session, I released it back to the wild, but its photos are now in my records with the code name HA1.

HA1 was one subject in an ongoing study looking at the relations between the dimensions of snails' feet and shells. One way of getting that information is to take pictures of snails from below while they are crawling on glass. The ruler provides the necessary scale.

When I took a closer look at the above picture a few months later, I noticed that the snail's jaw was also visible. Here is the relevant detail from the same picture.

Despite its name, the gastropod jaw is only remotely analogous to the vertebrate jaw. The jaw is attached transversely to the upper margin of the mouth. The snail uses its jaw to scrape off food particles, for example, algae, from surfaces or to rip off pieces of food, for example, leaves, and to push them into the mouth cavity.

In search of forgotten knowledge

2011-11-03T19:28:00.000-04:00

I spent several hours today looking up ancient information in ancient books. Thanks to sites like Google Books and the Biodiversity Heritage Library, one can now do that sort of research right from one's computer. Who needs libraries anymore?

The keyword I used for my searches was, of course, snail.

Among the not-so-dusty tomes I discovered was The system of natural history (1800) compiled from the writings of Comte de Buffon.

Buffon's book was the newest of the books I skimmed. The oldest one was John Hill's An history of animals: containing descriptions of the birds, beasts, fishes, and insects of the several parts of the world from 1752. I'm not sure who John Hill was.

The most interesting find, so far, was Microscopic observations or, Dr. Hooke's wonderful discoveries by the microscope by Robert Hooke (1780).

More than 200 years ago Hooke gave a fairly accurate description of how most terrestrial gastropods move (spellings and capitalizations are original):

Its Way of moving from place to place, though destitute of Feet, is effected by two large muscular Skins, that are lengthned by letting out; after which, their Fore-part is shortned into Folds, and the hinder Part falls into the fame Contraction: Then the Fore-part extends, and draws along the Shell. A glutinous Slime emitted from the Body, enables it, at the fame time, to adhere firmly and securely to all Kinds of Surfaces, which is an Advantage few Animals that have Feet can pretend to.

Hooke also described the jaw of a snail. I will write about that in a future post.

Ventridens suppressus and its mystery

2011-10-23T09:13:00.000-04:00

Most land snail species that have teeth or lamellae in the apertures of their shells develop them as they near sexual maturity. In a handful of species, such apertural formations are present in young snails, but diminish in number and size or disappear completely in adults. The North American snail Ventridens suppressus is in the latter group.

The apertures of the shells of newly hatched Ventridens suppressus are unobstructed. Up to 5 lamellae develop in their apertures as the snails go thru their ontogeny. But as they approach maturity, the lamellae get resorbed one by one and the adults end up with 1 small tooth. Sometimes even that disappears completely.

Here is one individual that I found recently (shell diameter was ~5 mm). It has 2 lamellae in its aperture. This is Pilsbry's 3rd neanic substage (Fig. 235 in Land Mollusca of North America, vol. II:1).

In a paper that came out about a year ago, I hypothesized that in the aperture of the shell of the semi-terrestrial snail Pedipes ovalis, one long lamellae functions to protect the penumostome (breathing hole) from the movements of the foot.

I have long been puzzled by the lack of apertural formations in young shells and, in the case of species like Ventridens suppressus, in old shells. If they have a function, why are they not present at all life stages?

A soiled Anguispira

2011-10-16T04:57:00.000-04:00

The land snails in the genus Anguispira spend the winters buried in soil among the roots of trees. In November 2009, I wrote about 5 dormant Anguispira fergusoni that had become dormant for the winter.

A couple of days ago when we were looking for slugs in the park near our house, my wife discovered several of the same snails among the roots of a tree.

The shells of all the snails were coated with mud. They had probably been awakened from their sleep in the soil by the heavy rain we had had the day before.

I intend to go back to the same tree next weekend. I will search for the snails and if I find them, I will mark their locations in the soil with little flags. Then I will monitor them throughout the winter.

I also need to figure out a way to mark the shells of the snails for later identification.

A box of plasticine

2011-10-09T09:18:00.000-04:00

This tinful of plasticine tops the list of things I have used more or less continuously for the longest time. I bought it in London during a very short visit to England in September 1975. That was 36 years ago*.

I don't think I had a clear purpose in mind when I bought it. And for a long time I didn't do much with it. However, it gradually acquired a unique function in my photographic activities: I now use pieces of it to position snail shells when I'm photographing them.

Originally, each color was a separate stick. After years of handling, the colors are slowly amalgamating. I suspect 35 years from now there will be one mass of indeterminate color.

*The tin is not original; it's an Altoids box.

Old Discus rotundatus

2011-10-04T08:38:00.000-04:00

In the summer of 2008 when I was in Montreal for a few days, I collected some snail shells, which I later identified as Discus catskillensis, a species native to North America. There were, however, objections to my identification and knowledgeable readers proposed that the snails I had found were instead Discus rotundatus, a European species introduced to the U.S. and Canada.

After a long hiatus and with additional specimens collected last summer, I have now decided to pinpoint the identification of the Discus of Montreal for once and all.

I have at hand several lots of Discus species from museums that I will be comparing with the Montreal shells. Here are 2 lots of Discus rotundatus.

This one was collected in Sweden in July 1923 by someone named B. Sundler. Then it passed into the hands of R. Jackson before coming to the DMNH. I am not familiar with either of those names.

The 2nd lot is even older. It was apparently collected by a Mr. Schenk in Switzerland before joining the collection of Victor Sterki. Sterki (1846-1933) was born in Switzerland. So these shells may very well have been taken before Sterki emigrated to the U.S. in 1883.

Old museum shells with associated bits of papers that reveal the collectors names and locality data do have some nostalgic charm. Here is a related post.

Measuring diameters of tall shells

2011-09-29T21:51:00.000-04:00

There are 2 basic shapes of snail shells: tall shells and wide shells. It is easier to measure the height (length) of a tall shell than it is to measure its width (diameter). The reverse holds for wide shells. In other words, because of their uneven shapes, the longest dimension of a shell is always easier to measure than the shorter ones.

The "standard" diameter of a tall shell is measured perpendicular to the coiling axis, also known as the columella (the white line in the picture) of the shell.

But this requires that the columella be held parallel to the caliper jaws. Easier said than done. To take the above picture, I had to support the shell with plasticine.

Some years ago, I realized that it was much easier to measure the oblique diameter of a shell. Here is one way of measuring the oblique diameter*. Note that the columella is not parallel to the caliper jaws.

The 2 diameters are, of course, not equal to each other. The perpendicular diameter of the shell in the pictures was 5.8 mm, while its oblique diameter was 5.5 mm.

The shell in the pictures is Batillaria minima, the subject of 2 manuscripts I am currently writing.

*I showed another way of measuring the oblique diameter in this post. It is imperative that the measurement method be explained in a manuscript so as not to leave any uncertainty.

The native and the alien

2011-09-25T22:26:00.000-04:00

Back in 2006, for a brief period I kept an individual of the native philomycid slug Philomycus carolinianus and an individual of the introduced slug Arion subfuscus in captivity. The slugs lived in the same container and as far as I could tell, their interactions were peaceful. I published my observations as a short note in the 2007 issue of Tentacle (p. 14).

About a week ago, I made a similar observation, this time in the wild. I was searching for Megapallifera mutabilis, another philomycid slug. I found one squeezed inside a tight crevice in a tree and there was an Arion subfuscus a few centimeters below it.

If the 2 species had antagonistic interactions, they probably wouldn't rest so close to each other. Or would they?

One more well hidden tree frog

2011-09-21T17:50:00.001-04:00

A gray treefrog, Hyla versicolor or H. chrysoscelis, in the cavity of a tulip poplar.
The previous well hidden tree frog post was here.

Snails of an Ottoman fort

2011-09-19T18:36:00.000-04:00

Back in July 2010 when we were in Turkey, we spent one afternoon visiting the ruins of an Ottoman fort in the village of Rumelifeneri at the entrance of the Bosphorus from the Black Sea.

The main purpose of our trip to the site was, of course, to collect land snails. The paper presenting the results of our little survey just came out in Triton. You may download a pdf version of it from here.

The snail fauna of the location was impoverished in terms of the number of species, although the shells of the existing snails were abundant. The most noteworthy find was the 2nd ever record of Discus rotundatus from Turkey.

A pickup for slugs

2011-09-16T19:12:00.000-04:00

Last Sunday we took a walk along a wooded park in a slightly rural area. Near the end of the park there were some isolated houses and in front of one of them was an old, dirty pickup truck.

I noticed some peculiar marks on the dust-covered hood of the truck.

On close inspection, they turned out to be slug feeding tracks.

These slugs normally graze on layers of blue-green algae (cyanobacteria, actually). But what was covering the hood of the truck didn't look anything like algae to me. It was for like a blackened crust of street dust. There must be something nourishing in it, though.

Here is another post about the discovery of slug tracks in an unexpected spot.

But was I art?

2011-09-13T19:06:00.000-04:00

Back in July when we were in Pittsburgh for the American Malacological Society's annual meeting, my wife and I also visited Wood Street Galleries. There was an exhibit called "Long are the Days, Short are the Nights" featuring a group of artists from Iceland, the country that insists on slaughtering whales.

There were some intriguing pieces, including this one called Rotating Unit by Egill Saebjörnsson.

It consisted of a rotating piece of chicken wire thru which patterns of light were being projected on the nearby wall.

I couldn't resist the temptation to include myself in the display.

Maybe that's the whole point of art.

Asian tiger mosquito caught on film

2011-09-11T12:27:00.001-04:00

Prior to the early 20th century, there had been many deadly epidemics of the virus-caused illness yellow fever in the Americas. In 1881, the Cuban doctor Carlos Finlay proposed that the disease was transmitted by mosquitos. To establish that mosquits were indeed the vector of yellow fever, the American army surgeon Walter Reed carried out experiments with human volunteers in 1901. The volunteers allowed themselves to be bitten by mosquitos that had previously fed on yellow fever patients. Some of the volunteers contracted yellow fever and died from it.

I don't think I would ever volunteer for such a heroic act. Nevertheless, yesterday I allowed an Asian tiger mosquito to feed on my arm for more than 30 seconds so that I could film it. Here is a 10-s clip for your enjoyment.

Not much happens actually. It would be more interesting to catch a mosquito in the act of inserting its proboscis thru the skin. But that would probably require quite a bit of luck, many trials of filming and not to mention very cooperative volunteers.

Sorry for the shakiness of the clip; it was difficult to hold the camera steady with 1 hand at the high magnification I was using.

A new website for alien gastropods in North America

2011-09-08T21:34:00.002-04:00

The United States Department of Agriculture's Animal and Plant Health Inspection Service has just made public Terrestrial Mollusc Tool for those terrestrial gastropods that are likely to be introduced into the U.S. from foreign countries.

The primary users of the tool are intended to be customs inspectors at U.S. ports of entry whose duties include the spotting and the identification of live snails and slugs that may be intentionally or unintentionally being brought into the U.S. These include the pest species such as the giant African snails (Achatina spp.). But the key should be useful to everyone who is attempting to identify the non-native gastropods, for example, Cepaea nemoralis, already established in North America.

The tool also provides useful information on the biology and study of gastropods, including well-illustrated instructions for dissecting snails and slugs.

As mentioned in the Acknowledgements, yours truly was one of the "expert" reviewers of the beta version of Terrestrial Mollusc Tool.

2 clueless trees

2011-09-07T19:09:00.000-04:00

This beech (left) and the tulip poplar next to it have obviously not heard of the dictum that species are supposed to compete with each other. This picture doesn't reveal that they are both about equally tall and, so far as I can tell, equally healthy. That they have grown so well so far is an indication that they are actually tolerating each other.

Then again, maybe they are in a fierce competition. It's hard to tell what's going on high up in the intertwined canopy or deep among the tangled roots.

Weekend gastropods

2011-09-05T17:31:00.000-04:00

The warm and humid weather over the weekend had brought the slugs out. On Saturday morning, I was able to collect 20 Megapallifera mutabilis in an hour. I brought them home and weighed them to add more data to the population cycle project that has been going on for 2.5 years (more info here).

These slugs have a tendency to aggregate both in the wild and in captivity. This is called huddling.

During our Sunday morning walk, I returned the slugs unharmed to their favorite trees. My wife and I then walked to a spot where 2 days earlier we had collected about a dozen shells of the snail Neohelix albolabris. We searched for about a half an hour and found another dozen or so. We did not see any live snails, but I found one that had died recently. The snail's body was still intact and it hadn't started to smell yet. So I brought it home and saved it in alcohol.

That was the 2nd population of Neohelix albolabris in the park near our house that we have come across this year. I wrote about the 1st one here.

Methylene blue

2011-09-03T20:21:00.000-04:00

An ancient surface

2011-09-01T20:52:00.002-04:00

This is a close-up of a fossil bivalve shell from the famous Calvert Cliffs of Maryland. It is probably a Chesapecten sp., maybe about 5 million years old.

Pavement kitty

2011-08-31T13:47:00.000-04:00

Lake Champlain's zebras

2011-08-28T20:19:00.000-04:00

We left Montreal Friday morning and a couple of hours later left Canada near Rouses Point, New York. After exiting the U.S. border station, we took Route 2 that crosses Lake Champlain into Vermont. While still on the bridge, we stopped for lunch at a convenient parking lot facing north.

After I finished my sandwich, I had my customary quick walk along the shore of the lake to check out the local mollusk fauna. These small mussels were abundant on the rocks at the edge of the water.

If I am not mistaken, they are the infamous zebra mussels (Dreissena polymorpha) that have been present in Lake Champlain at least since 1993.

These mussels are native to southeast Europe. They were 1st seen in North America in 1988. Despite its small size, the zebra mussel is a nuisance species, because it is invasive and often present abundantly (more info from the USDA).

Trochulus hispidus in Montreal

2011-08-25T21:41:00.000-04:00

I spent part of my last full day in Montreal photographing and filming the snails I found in my sister's garden. One of them was the following.

The diameter of the shell was 8.7 mm. Note the hairs visible along the edge of the body whorl. Based on the descriptions in Identifying Land Snails and Slugs in Canada – Introduced Species and Native Genera, I have identified this specimen as Trochulus hispidus (the other candidate is T. striolatus). It is a native of Europe that has been introduced to Canada.

Cepaea nemoralis at Bishop's Mills

2011-08-24T08:44:00.000-04:00

Yesterday on our way to Ottawa we stopped at the village of Bishop's Mills and paid a visit to our naturalist friend Fred Schueler. Our sojourn culminated with a search for the snail Cepaea nemoralis. Our expedition was brief, though, and barely extended beyond the lily patch across the road from Fred's house.

We did find several of our favorite snails on the soil under the lily leaves and among the grass.

How these snails, which are native to Europe, came to be in Bishop's Mills is a question we will leave unanswered for the time being.

The snails of Skaneateles Lake

2011-08-22T08:48:00.000-04:00

This week I am in Canada. Yesterday morning on our way to Niagara Falls thru New York, we stopped at the northern shore of Skaneateles Lake for a short walk along the lake and on the pier that extends into it.

These operculated snails were abundant on the shore.

I suspect they are a non-native species of apple snail (family Ampullariidae). A more definite identification will hopefully follow after I've had a chance to send their pictures to more knowledgeable people.

A scatter plot for Albinaria

2011-08-18T20:49:00.000-04:00

In the previous post, I presented a histogram for the heights of a sample of 131 adult shells of an Albinaria species. Now here is a bivariate plot of shell heights (H) against shell diameters (D) for the same sample.

Height and diameter are about equally variable and they are also correlated with each other. What could this mean?

If the snails were under strong selective pressure to conserve their shell volumes, we would expect a negative correlation between H and D: when H became large, D would be smaller and vice versa. So a plot of D against H would look like this:

I obtained this plot by calculating a hypothetical value of D for each measured value of H at a constant volume. I obtained the volume from the mean H and D values for the sample assuming that the shell shape was a cylinder. Of course, in a real-life sample there would be scatter arising from biological variation and measurement error.

The positive correlation between H and D in my sample (1st plot) indicates that shell volume is not conserved. What is under selection is probably the shape of the shell. But what is the significance of shell shape?

Let this be tonight's food for thought. I will probably return to this topic in the future.

A histogram for Albinaria

2011-08-16T19:42:00.001-04:00

Regular readers may have noticed that one of my passions is to measure snail shells. I have written about the variability of shell dimensions on several occasions, for example here. Naturally, I have pages and pages of data waiting to be analyzed and made sense out of.

Today, I entered a set of measurements from 2004 into the computer. They belong to a sample of 131 shells of an Albinaria species that we had collected in 2002 in Turkey. Here is the histogram for shell heights.

I haven't run any statistical tests, but the distribution looks roughly normal. The 2 specimens making up the right-hand tail seem to be outliers. However, the relative coefficient of variation* is 5.8%, which is quite ordinary for shell heights of tall-shelled land snails. So those 2 shells actually lie within the expected range of variation for a sample of this size.

The 2nd entry in this series is here.

*(standard deviation/mean)x100

A challenge for hand-held close-up video photography: a speedy inchworm

2011-08-14T19:36:00.000-04:00

And now for something completely different: the video of an inchworm looping on my deck.

As you can imagine, it wasn't easy to follow this little guy with the camera while keeping it in focus and at the same time without shaking the camera too much. It was about 16 mm long.

Lights, camera, Euxina circumdata!

2011-08-11T09:20:00.000-04:00

I bought a new camera recently that can take high resolution videos, which I intend to use to film my favorite creatures. The ultimate aim is to better understand their behavior and functional anatomy.

I am more or less a novice at this and still learning the tricks of video photography, especially of the close-up, hand-held camera kind. The experience I have gained from years of still photography helps, though.

Here is one of my 1st attempts at snail cinematography. The subject was an adult Euxina circumdata with a shell length of 11.7 mm.

Do remember that at such high magnifications the depth of field is very short as it would be in any kind of close-up photography. As a result, not everything is in focus simultaneously. But the nice thing about using a hand-held camera is that I can move it back and forth to bring different parts of the subject in focus.

Notice how short the snail's foot is relative to its shell. Because of that size discrepancy, the snail can't lift its shell up when crawling on a horizontal surface. I have written about this before in this post. Nevertheless, the adhesion provided by the short foot is more than enough to support the weight of the snail's body and its shell when it's crawling sideways as you can see in the video or even upside down.

I had to reduce the resolution of the file to be able to upload it here. The original uncut version is 225 MB.

The lizard of Magnesia

2011-08-09T18:32:00.000-04:00

This was probably a Laudakia stellio, a relatively large lizard that inhabits rock outcrops, ruins and even the walls of houses in western Turkey and elsewhere.

I saw this one on one of the surviving walls of Magnesia on the Meander last July in Turkey. They are quite skittish, as are most lizards, and quickly disappear inside a crevice as soon as they spot an approaching human.

A telephoto lens would have produced a better picture, but I didn't have one with me.

Busy as a carpenter bee

2011-08-07T21:19:00.000-04:00

I am into making videos these days. Here is a carpenter bee I filmed this morning.

I am still in the learning phase. I hope to get better as I get more practice and develop my techniques in the art and science of close-up moving pictures, my primary interest.

So expect more video clips on this blog from now on.

A hot squirrel on its belly

2011-08-05T21:20:00.000-04:00

On very hot days it's not unusual to chance upon flattened squirrels on sidewalks or streets. The 1st time I saw a squirrel like that it was so flat that I thought it had been run over by a car. But when the squirrel noticed me it got up and ran to the nearest tree.

After the squirrel in the picture above ran away, I walked over to the shady spot where it had been lying and flattened my palm on the asphalt. It felt cool. Apparently asphalt and concrete conduct heat well. So by flattening its belly against such a surface, a squirrel loses body heat and lowers its body temperature. That's a good thing to achieve on a hot day.

Initially I thought the belly-cooling behavior had probably originated among the city-dwelling squirrels within the last 200 years or so. But when I searched the internet for more information, I saw pictures of squirrels lying on soil or wood chips. The behavior may in fact be an ancient one.

A hot rock

2011-08-03T14:26:00.000-04:00

The eastern North America has been under the influence of a heat wave that hasn't quite abated yet. For about 3 weeks now, the daytime temperatures have been hovering around at least 30ºC (what's that on the Fahrenheit scale?).

July 22nd was an exceptionally hot day. At 1545 a few centimeters above the soil in my backyard, I measured an air temperature of 39.3ºC. When I put the probe of the thermistor in contact with the surface of a rock that had been baking in the sun, it shot past 46ºC*.

It eventually went up to 46.7ºC and would have gone up even higher if I hadn't gotten too hot from squatting out there and escaped inside.

My underlying purpose was to figure out how the snails and slugs that normally inhabit the undersides of those rocks were faring with the heat. I could not find any Vertigo to run a test, though. Had they all retreated deep into the soil?

*Admittedly, this was not a good measurement. The thermometer probe, being unshielded, was probably exposed to radiation. On the other hand, it would have been difficult to shield it while measuring the temperature of the surface of a rock.

Field trip at Powdermill Nature Reserve

2011-08-01T11:58:00.000-04:00

Following the American Malacological Society's annual meeting in Pittsburgh last week, a group of us went on a field trip on Thursday. The location was the biological research station of Carnegie Museum of Natural History, Powdermill Nature Reserve, near Rector, PA.

We spent about 2 hours in the woods searching for snails and slugs. Some of the finds included this slug, a Pallifera sp.

And there were several individuals of Mesodon thyroidus. This one was climbing a tree, something they often do on warm and humid days.

The next snail, Ventridens intertextus, was the highlight of the trip for me, for I had never seen this species before.

After field work, we had lunch, sorted and identified the specimens collected and socialized. Here is the group photo after lunch.

Reminiscences of the AMS meeting

2011-07-29T14:22:00.000-04:00

The American Malacological Society's 77th annual meeting took place in Pittsburgh the City of Bridges with the participation of an ever-dwindling number of about 70 malacologists. Most of them were American with a handful of Europeans. So where were all the other mollusc workers?

It seemed to me that most presentations were about terrestrial or freshwater molluscs. Which is fine with me, but it nevertheless made me wonder why there are so few scientists in the U.S. working with marine molluscs.

There was a nice session on the history of malacology. If I'm not mistaken this was the only such session at least since 2003 when I 1st started attending these meetings. I've been told that a history of malacology session will be held also at the next year's meeting.

The meeting logo had been inspired by the well-known prints of the Pittsburgh native Andy Warhol.

My major complaint about the meeting is that the opening reception took place on Saturday night before the meeting had actually started. I certainly had no intention of arriving in Pittsburgh a day early (and paying for the hotel for an extra night) just to attend a reception. A much sensible spot for the reception was the Sunday night.

The meeting room was also too cold.

I had 2 presentations at the meeting both of which, I think, went well. Here is a short film clip of me during my presentation on Assiminea succinea.

The next year's meeting will be in Philadelphia.

Following the meeting on Thursday we had a fun field trip. I will write about that in a few days.

Andy Warhol would want you to stop thinking (but to keep on buying)

2011-07-26T21:36:00.000-04:00

Today was our 2nd full day in Pittsburgh. I took a break from the American Malacological Society meeting and visited the Andy Warhol Museum with my wife.

Warhol was born in Pittsburgh and the museum dedicated to him is the place to learn about him and his art.

Besides Warhol's original artwork, the museum also shows the movies he made, including Sleep, the almost 5.5-hour long film of his lover John Giorno sleeping. I could only watch about a minute of it. But Mario Banana was quite amusing.

According to a display in the museum, Warhol once said "Buying is much more American than thinking, and I'm as American as they come."

Although I may not care for much of what Warhol did or believed in, his museum was fun to visit. And we did buy some reprints of his work.

Monongahela from Duquesne

2011-07-25T21:56:00.000-04:00

I am in Pittsburgh this week for the American Malacological Society's annual meeting. The meeting is taking place in Duquesne University.

Duquesne is on a hill overlooking the Monongahela River. This is the view of the river from the very back of the university.

Archaeo+Malacology Group Newsletter No. 19

2011-07-22T11:27:00.000-04:00

The AMG Newsletter No. 19 is available here.

An interesting article by Claire Perrette in this issue is about the ornaments made from marine shells that were found at a neolithic site in the Fijian Archipelago. A nice photograph shows the different types of ornaments.

In 3 articles Henk Mienis writes about various mollusk finds at archaeological sites in Israel.

There are also the usual abtsracts of relevant papers from the literature as well as information on past and future conferences.

A variety of penises

2011-07-20T21:34:00.000-04:00

One of the 2 talks I will be presenting at the American Malacological Society meeting next week in Pittsburgh will be about the semi-terrestrial snail Assiminea succinea.

To learn more about the anatomy of Assiminea, I dissected one snail last weekend. It was a male, because it had a penis. To get a good picture of the penis, I removed it from the snail. Here it is.

The picture on the left shows the penis as it was curved while attached to the snail's body. During copulation the penis would be straightened and would look more like the way it does in the picture on the right.

The shell of the snail was 2.31 mm long. So its penis was about half the length of its shell. Talk about a long member.

Then I went thru my papers and found drawings of the penises of several species of Assiminea in a paper by Abbott*. Here they are.

Penis anatomy would definitely be a useful characteristic in a future revision of Assiminea systematics. But, no I don't intend to do that.

*Abbott, R. T. 1958. The gastropod genus Assiminea in the Philippines. Proceedings of the Academy of Natural Sciences of Philadelphia 110:213-278.

An unusual Eobania vermiculata

2011-07-18T18:02:00.000-04:00

Most individuals of our favorite land snail Eobania vermiculata have shells with 5 bands, although some of which may be fused into wider bands.

One may occasionally come across shells that are devoid of bands. In the picture below the shell on the left is the usual variety, while the one on the right is "bandless".

Presumably, the bandless shells form when all the bands merge to create one diffuse pattern. Here is another example.

What happens when you poke a grasshopper?

2011-07-16T21:34:00.000-04:00

This is what happens.

Osilinus turbinatus in its habitat

2011-07-14T21:14:00.006-04:00

Many snail species that live in the transition zone between the sea and the land blur the boundary between aquatic and terrestrial species. They usually spend most of their lives outside of the sea. Yet, they cannot move far from it, because in one way or other, their livelihoods are tied to the sea.

One such snail is Osilinus turbinatus (Vetigastropoda: Trochidae). This species is very common on rocky coasts of the Mediterranean Sea. Here is one individual at its usual habitat that I filmed in Turkey back in June (yes, the snail is that thing near the center of the screen).

Osilinus turbinatus has traditionally been considered a marine snail. But it seems more comfortable outside the sea than in it as long as it is within reach of occasional waves.

I will write more about Osilinus turbinatus in the future.

Luciferase and sex: fryflies mating #1

2011-07-12T18:27:00.000-04:00

Fireflies seem quite abundant this year and their evening attempts at procreation have not ebbed yet. Here is a pair mating (see this post for a similar picture).

This is the position in which mating pairs may be seen most often. But, how do they get into this position? Surely, males and females can't be crawling backwards until they bump into each other. Remember that prospective firefly mates locate each other using light signals. Males fly around flashing their lights at species-specific intervals and the females waiting on the ground respond with their own species-specific flashes.

Here is the 1st video I ever made of a pair of fireflies locating each other and then initiating copulation.

The firefly seen in the beginning is the female. She is flashing to a male that was initially not visible. He soon appears on the left, flashes once in response and then flies to the leaf the female is on and climbs on her back. The pair spends about 45 seconds in that position. During that period the male can be seen caressing, if I may anthropomorphise a bit, the back of the head of the female. Its antennas are also quite active, while the female, as far as we can tell at this magnification, is quite immobile, although I suppose she is monitoring the male's activity patterns. Are they making one last check to make sure that they are of the same species? Somewhere along the line, the male enters the female and then turns around to assume the typical mating position.

These are probably a species of Photinus, but that's as far as I can go with an identification.

American Malacological Society meeting coming up

2011-07-10T22:57:00.000-04:00

The annual meeting of the American Malacological Society will be held in Pittsburgh, PA from Saturday, July 23rd thru Thursday, July 28th, 2011. More information is available here.

The abstracts and the program are available as a pdf file here.

I will be giving not 1, but 2 presentations. The abstracts of my talks are on pages 60 and 61 of the pdf file. I have never given 2 presentations at a meeting before. I have spent the last 3 weeks working on my talks and I am not finished yet.

Both of my talks are based on topics I have written about on this blog on several occasions. One of my talks is about the semi-terrestrial snail Assiminea succinea. I will present an overview of everything I have so far learned about that little snail.

My 2nd talk is in the History of Malacology Symposium. It will bring together my ideas concerning 3 different subjects: the snail research of Richard Thomas Lowe (1802-1874), mosaic evolution and Hasok Chang's proposal of the practicing of the history of science as a "complementary science" to contribute to the advancement of present day science. Hopefully, my attempted synthesis will make sense.

Flashing firefly flying for fertilization

2011-07-08T17:48:00.000-04:00

The backyard fireflies are still carrying on their annual rite of luciferase, photons and sex. Here is a movie I made of a flying male.

To be continued.

Turtles of Magnesia

2011-07-06T19:47:00.001-04:00

While exploring the ruins of Magnesia on the Maeander for snails last month in Turkey, I noticed a whole bunch of turtles in the nearby creek.

The creek, whose name I haven't bother to look up, was probably a tributary of the River Meander, which was not too far away. The banks of the creek were extremely muddy. The water level in the creek probably fluctuated depending on rainfall or on the amount of water removed for agriculture. These particular turtles apparently like the mud.

We were on a bridge above the creek. Despite the fact that the bridge was quite high, the turtles entered the water as soon as they spotted us peaking down. This was the closest picture of one I could get.

Based on the habitat and range information in the book I have on the amphibians and reptiles of Turkey*, the turtle is probably Mauremys caspica. But when it comes to turtles, I am just a bystander. So I could be quite wrong.

*Ibrahim Baran. Türkiye Amfibi ve Sürüngenleri. Tübitak. 2005.

Firefly on the window

2011-07-05T18:14:00.000-04:00

Fireflies have been coming out in throngs every night around our house. They are always enchanting to watch. This one landed on the kitchen window the other night.

Besides the light producing organ near the end of the abdomen, the eyes are also noteworthy. I didn't know fireflies had such big eyes. This is, however, not surprising; an animal that finds its prospective mates by mutual light signals in the dark would be expected to have evolved large eyes.

The view from N9

2011-07-03T09:42:00.000-04:00

While I was searching for and collecting snails, primarily Albinaria, my wife filmed me and the scenery one day last month in Turkey*.

We were at my station coded N9. N9 is a limestone hill rising from the filled-up delta of the river Küçük Menderes, the ancient Cayster. During the Roman times, this hill was undoubtedly an island before the silt brought by the river filled up the delta. The Aegean Sea is visible in the background in the beginning of the movie.

N9 is the site of an ongoing experiment started back in 2006. That was the subject of this post from a year ago.

*It was a windy day and most of what the camera's microphone recorded was the sound of the wind. So I turned the sound off while editing this clip from the original longer film.

Happy Evolution Day!

2011-07-01T12:37:00.000-04:00

On this day in 1858 Charles Darwin’s and Alfred Russel Wallace’s independently developed ideas on evolution by natural selection were made public for the first time during a historic session of the the Linnean Society in London.

Darwin had been developing his ideas for 20 years, but before that day he had revealed them only to a few close friends and correspondents, including the American botanist Asa Gray. Wallace, on the other hand, had come up with his version of natural selection, very much similar to that of Darwin's, several months earlier while doing fieldwork in the Malay Archipelago and communicated it to Darwin in a now famous letter*.

The presentation at the Linnean Society was initiated with a letter of introduction by Darwin’s close friends Charles Lyell and Joseph D. Hooker, opening with the words:

My Dear Sir, -- The accompanying papers, which we have the honour of communicating to the Linnean Society, and which all relate to the same subject, viz. the Laws which affect the Production of Varieties, Races, and Species, contain the results of the investigations of two indefatigable naturalists, Mr. Charles Darwin and Mr. Alfred Wallace.

This was followed by the reading of extracts from an unpublished essay Darwin had written in 1844, part of his 1857 letter explaining his ideas to Gray and the manuscript Wallace had sent to Darwin.

Why not celebrate this great idea today and everyday? Read a book on evolution, teach someone about evolution, visit a natural history museum or take a hike in the woods or go to a sea shore to witness the products of evolution. And don’t forget to remember Darwin and Wallace, for, after all these years, their idea remains indefatigable.

Hooray to the bearded guys! Pictures of Darwin (left) and Wallace are from the Linnean Society.

*According to the Darwin Correspondence Project, Wallace's letter and unpublished manuscript are missing.

An unusual Albinaria

2011-06-30T22:32:00.000-04:00

When land snails become dormant attached to vertical surfaces, they almost always point the apexes of their shells downward. Every now and then, however, one may come across a nonconformist snail sleeping on a wall with its apex up. I presented an example of such a snail in this post.

Here is another one.

These snails are Albinaria lerosiensis. I photographed them in Turkey earlier this month. Both snails had become dormant on the side of a limestone rock for the dry Mediterranean summer. The snail on the left was in the normal orientation with its apex down, while the one on the right had its apex up.

The snail on the right had another idiosyncracy: its apex was missing. Such decollated individuals are occasionally seen among individuals with intact shells.

Sea urchins of the Aegean

2011-06-28T20:44:00.000-04:00

Sea urchins are fun as long as there isn't one under your bare foot.

These urchin tests were all from the same location in western Turkey. Their differing colors may indicate that they belong to different species. Alternatively, they may be color variations of one species. But there are also size differences: the reddish ones never seem to grow as large as the green or the purple ones.

Leave a comment if you think you can enlighten us.

Reveal-it-all toilet facilities open to public

2011-06-27T12:24:00.001-04:00

Earlier this month while I was in Turkey, I went back to Magnesia on the Maeander, one of the 2 ancient cities in western Turkey named Magnesia. This time I discovered a particular attraction in the ruins that I had missed a year earlier: the communal toilets.

A nearby display in English explained thus:

The Public Lavatory (Latrine) 4.-6. Century A.D.
A vestibule with a pool; in the second room two fountains, benchs [sic] for sitting along the three sides for appr. 20-25 pupil [people], run-off water to cleanse before the bench and running water under the seating to carry refuse from there. Excavated 1993-94; partly restored 1995.

I suspect the top of the bench was modern, because only 2 of the seats had full openings, while the rest were just depressions.

The accompanying picture on the display showed several men using the facility.

But where did women go to relieve themselves?

White wagtail on the roof

2011-06-24T14:59:00.000-04:00

I am not much of a birder and the number of bird species I can identify on sight is probably only about 20. So, I often try to photograph the ones I find interesting and unfamiliar with the hopes of putting a name on them later.

Here is a bird I noticed a couple of weeks ago while vacationing in western Turkey. The longest lens I had with me was 50 mm, but luckily, the bird was not too skittish, so I was able to get a few satisfactory pictures of it. If I'm not mistaken, it is a white wagtail (Motacilla alba). It is stated to be a common species of Europe, Asia and northern Africa.

Airbus touchdown

2011-06-22T06:39:00.000-04:00

The airplane we took from Istanbul to Washington, DC yesterday had 2 external cameras, one facing the front of the plane, while the other the ground underneath. Their continuous output was available for watching in the computer monitors in the back of every seat. For most of the flight, all we could see was an endless stream of clouds, but roads and houses became recognizable once the plane started its descend.

As we were approaching the runway, the bottom camera got turned off, but the front one stayed on, giving us an exciting, if scary, display of our landing.

A minuscule arthropod

2011-06-19T07:19:00.000-04:00

The other day while searching for snail shells in fine gravel I had brought home from a beach, I noticed a white speck moving rapidly among the sand grains. It appeared smaller than the period at the end of a sentence. Despite its high speed, relative to its size, it went only a short distance, relative to my size, before it hid itself under a sand grain. That made it easy to relocate it by getting it to move again by touching a few grains.

Here are the pictures of it I took before I lost it for good.

I suspect it was a mite of some sort. Its body was about 0.25 mm long (the ruler division next to it was 1 mm long).

Getting seriously interested in marine snails

2011-06-17T12:46:00.001-04:00

One of the joys of my childhood was beach combing. Some of the shells from those days still survive, still unidentified. Over the years, I have had occasional opportunities to collect seashells, but never too seriously. This week, however, I have returned to my old passion.

We are staying at a seaside town on the Aegean coast of Turkey where we are likely to return in the future. So, I figured a checklist of the local coastal mollusks wouldn't be a bad idea. No such list has probably been published and therefore, there is potential for a publication.

I have so far collected a large number of shells adding many species to the yet to be constructed list and also adding quite a bit of potential weight to my suitcase on my flight back home. I also took some fine gravel from one of the locations, the sorting of which afterwards provided hours of fun and perhaps 30 species of tiny mollusks.

My knowledge of marine mollusks is meager and so, my main difficulty will be identifying the specimens, especially the very small species. Hopefully, by the use of various internet resources and books and with a little help from friends.

Experiment in progress: land snails in the sea

2011-06-15T05:16:00.001-04:00

Darwin may have been the 1st scientist to test the survival of land snails in sea water. He never published the results of his experiments as a separate paper, but wrote about them in his letters and summarized them briefly in the Origins of species. You may read a synopsis of his experiments in this paper of mine.

Darwin was trying to determine if land snails could disperse between continents and islands by floating in the sea. This was important for him to know, because he had figured that the snail species on islands had either arrived there from somewhere else where they had originally evolved or had been created separately on each island.

Several mechanisms are responsible for the dispersal of land snails across water. Floating freely or while attached to floating wood may be one of them. I don't know if anyone else has tested the survivability of land snails in the sea (water) since Darwin. I am spending my vacation by the Aegean Sea in a town where the snail Eobania vermiculata is extremely abundant. So, earlier this week I decided to follow in Darwin's footsteps and run a few experiments of my own.

Here are Eobania vermiculata floating in sea water.

There were casualties in the name of science. But before accusing me of animal cruelty, remember that this is a species that is killed in boiling water by the thousands in the name of gastronomical satisfaction.

A full report will await further tests and intense contemplation.

Not exactly a bird at the bird feeder

2011-06-12T09:14:00.000-04:00

Why, it's a chipmunk, of course.

Notes on Melarhaphe neritoides

2011-06-12T08:11:00.002-04:00

Two days ago I spent about an hour observing and photographing the semi-terrestrial snail Melarhaphe neritoides* in a rock pool by the Aegean Sea. This was in the morning and all of the snails, save one, were dormant on the rocks above the water. The one odd Melarhaphe was in the pool crawling slowly on the rocks.

The sea was rough and every time a wave breached over the raised edge of the pool, the water level in the rock pool went up and submerged the snails on the rocks for a few seconds. But the snails appeared oblivious to the water and remained inside their shells. Perhaps, they were waiting for the night time to start their activities. It may not be a bad idea to visit the spot after sunset to check up on the snails.

*Family Littorinidae.

A mysterious tube at low tide

2011-06-10T15:46:00.000-04:00

Back in April when we were in Florida, I spent several hours one afternoon at a tidal mudflat near the Honeymoon Island outside of Tampa. The tide was out and it was a good time to collect data on the intertidal snail Batillaria minima.

At the edge of the receding water outside the range of Batillaria minima, which lives quite close to the high tide mark, I saw a tube sticking vertically out of the mud.

I suspect it was the case of a polychaete worm. The worm itself was probably deep inside in a water-filled chamber waiting for the water to return. Either that or it was a drinking straw stuck in the mud. In the next picture my finger provides a scale.

A thirsty Eobania

2011-06-08T13:13:00.000-04:00

The land snail Eobania vermiculata is often present abundantly in urban parks and gardens in western Turkey. Of course, this is a good thing if one needs them for research purposes. Ever since I arrived in Istanbul last Saturday, I have measured the shells of about 80 of Eobania and photographed more than 15 crawling snails. And I'm not done yet.

Meanwhile, here is one Eobania vermiculata detecting and apparently drinking from a drop of water.

Where on earth is Vulgaria?

2011-06-06T10:21:00.000-04:00

One of my all-time favorite TV shows is The Man From U.N.C.L.E. from the mid-1960s. As I noted before, the producers of the show occasionally attempted to be politically correct, long before political correctness existed, by using silly fake names for various things. Another example of this was in the episode The Cherry Blossom Affair, in which the U.N.C.L.E.'s archenemy T.H.R.U.S.H. develops a device that induces earthquakes. To test the device the chief of the T.H.R.U.S.H. office in Tokyo selects a mountain named Kilo in a country named Vulgaria.

T.H.R.U.S.H. chief Harada, played by Jerry H. Fujikawa, announcing the target of the earthquake machine.
If Vulgaria was made up to avoid offending any real country, that was a needless precaution, for the U.N.C.L.E. agents Napoleon Solo and Illya Kuryakin interfered at the last moment, as is always the case, and destroyed Harada's machine. The use of the name of any real country, Bulgaria, Australia, you name it, would have been perfectly alright, I think.

Blogging will be intermittent

2011-06-03T15:33:00.000-04:00

...over the next 2.5 weeks as I travel in Asia Minor starting in a few hours. Unlike some trips in the past when the main focus was malacology, the present one is leaning more towards social studies. But gastropods are in 2nd place lagging not too far behind. In fact, some specific snail-collecting activities have been planned.

I will post on the blog provided that I have time and internet access. Otherwise, I have posts scheduled to publish once about every 3 days.

Behave while I'm gone. I promise I too will behave while on the road and will engage in partying, mild drinking and trespassing (in the name of science, of course) only occasionally.

Melampus and its foot

2011-06-01T22:57:00.001-04:00

The foot of Melampus coffeus (family Ellobiidae) is divided by a transverse groove into an anterior propodium and a posterior metapodium. The anatomy of its foot is similar to that of its cousin Pedipes. Also, in front of the propodium is the snout with the mouth going thru it.

What is the mechanism of locomotion of Melampus? Lack of time is preventing me from writing more on this interesting topic. But expect more in the future.

This is the 3rd entry in a series of posts about this species. The 1st one was here and the 2nd one was here.

Protoconchs of Assiminea

2011-05-30T22:45:00.001-04:00

There is a generalization that among closely related, especially congeneric, marine snails, the species with smaller protoconchs have planktonic larvae that go thru a free-swimming stage, while those with larger protoconchs have direct developing larvae that hatch out of their eggs as tiny crawling snails. The idea seems to go back at least to Verduin (1977) with possibly even earlier versions.

To compare the sizes of the protoconchs of related species, Verduin (1977) measured the following 2 dimensions of a protoconch, where D_n is the diameter of the nucleus of the protoconch and D_1/2 is the diameter of the 1st half whorl.

Since D_n is within D_1/2, the 2 measurements are tightly, in fact, linearly, correlated. Nevertheless, a plot of D_n versus D_1/2 is a useful way to separate groups of supposedly planktonic versus supposedly direct-developing species as Verduin (1977) showed to be the case with the species in the genus Alvania.

Recently, Aartsen (2008) noted that the application of Verduin's method to the Atlantic and Mediterranean species of Assiminea revealed the existence of 2 groups. However, he did not present a plot. So I added my own measurements of Assiminea succinea to Aartsen's measurements and did a Verduin plot.

To illustrate the intrinsic variability in the dimensions of such traits, I show here the measurements of 4 specimens rather than the mean value.

As far as I know, among these species, life history information is available only for A. grayana, which has planktonic larvae and for A. succinea, which has direct developing larvae. In the plot, the protoconchs of the former are smaller than those of the larger. So at least with those 2 species, we have agreement with the generalization that direct developing larvae are larger than planktonic larvae.

Aartsen. 2008. Basteria 72:165.
Verduin. 1977. Basteria 41:91.

Miscellaneous birds from the feeder

2011-05-29T21:04:00.000-04:00

I have photographed these birds within the last month.

Here is a common grackle,

...a male house finch, if I'm not mistaken,

...a catbird from behind,

...an unsure mourning dove,

...and last but not least, Mr. and Mrs. Cardinal.

Cat in the box

2011-05-28T22:22:00.000-04:00

My cat Marissa's trip to the vet is an ordeal both she and I have to endure once a year. The problem is that she refuses to go into the carrier voluntarily. If I attempt to force her in, she screams, hisses, scratches and even bites and I eventually give up. So last fall, I resorted to adopting a large cardboard box to transport her to the vet. I cut open a hole on one side large enough to shove Marissa in. The box itself is tall enough to prevent her from jumping back out before I shut the lid down and tape it up with duct tape.

I left the vet's office today with preventive medication for ticks and fleas as well as an instruction sheet on how to put a cat in a carrier. It looked so easy when they put her in the carrier I had brought with me. Then again, they do it many times a day. We will see how successful I will be the next time.

Meanwhile, here is Marissa Cat getting examined.

Batillaria minima and its foot

2011-05-26T22:53:00.000-04:00

I first encountered the intertidal snail Batillaria minima in Florida in 2006. Ever since then it has become one of my favorite snails. I have already published one short paper about B. minima's retractibility into its shell. I have also written about the species on this blog numerous times (for example, here).

Last month when we were in Florida, I was able to collect more data on various aspects of the biology of B. minima. For example, I photographed several individuals, juveniles and adults, from below while they were crawling on a glass plate.

Note in the picture how small the foot is relative to the shell. I am trying to understand how the snail's shell and foot grow relative to each other. I haven't yet had a chance to take measurements from the photos.

Expect more posts on Batillaria in the future.

Indian shell tools from Florida - Part 2

2011-05-25T22:00:00.000-04:00

After we looked at the Darwin & Dinosaurs exhibit in the Southwest Florida Museum of History in Fort Myers back in April, we went thru the rest of the museum. Expectedly, all of the exhibits were related to Florida history.

Various artifacts said to be Indian tools made from seashells especially attracted my attention. As I noted in this post written after visiting another Florida museum, I sometimes get skeptical when I read about the purported uses of various shell fragments. For example, these hammer-like tools made by securing snail shells to sticks were on exhibit at the SFMH.

Did the tools of the local Indians really look like these or are these the figments of archaeologists' or museum exhibitors' imaginations? Here is another example. This shell fragment was to supposed to have been a hammer. Would it not be more practical simply to use a piece of rock?

It was also stated that snail shell fragments like the one below were used as drinking bowls, especially during the ritualistic "black drink" ceremonies of the southeastern Indian tribes. This is certainly a more reasonable use for a shell.

Finally, there were these objects that were said to be columellas of snail shells. The columella is the central axis of a snail shell around which the whorls of the shell rotate. They were apparently worn as pendants. Perhaps, there are surviving authentic examples on strings.

Laughing gulls in a frenzy

2011-05-23T21:57:00.000-04:00

I filmed these laughing gulls in Florida last month. The sun was setting and the tide was moving out. The gulls seem to have been in some sort of day's end ritual that involved dipping their heads in the water.

Enlighten me if you know what was going here.

Discus versus Pleurodiscus

2011-05-22T22:56:00.000-04:00

To prepare a figure for a manuscript I am writing, I photographed some shells today. The shells were of 2 species found at one locality that we surveyed in Turkey last year. I wanted to show how superficially similar the shells of the 2 species are.

The shell marked A is Discus rotundatus, while the shells B and C are juvenile and adult, respectively, Pleurodiscus balmei. Actually, the fresh shells of the former species have reddish radial bands that make it easy to identify it. The shell pictured here, the best one I could find at this particular locality, is old and faded (more so is the juvenile P. balmei). The adults of D. rotundatus are also smaller than those of P. balmei.

Discus rotundatus is a European species that is occasionally encountered in Turkey, while P. balmei is native and quite common in western Turkey.

Here is a beaver

2011-05-21T10:13:00.000-04:00

Beavers abound in the lake near my house. I know that from the plenty of evidence they leave behind, which have been the subjects of several post (for example, here, here and here). But I had not actually seen a beaver in daylight-I did see the silhouette of one in the dusk once-until last weekend.

While taking a walk along the lake last Saturday, I spotted one Castor canadensis swimming in broad daylight. And luckily I had a telephoto lens on my camera. Here is the best shot of it.

Notice its long, flat tail.

A Nobelist tries to explain the nondevelopment of Islamic science and fails

2011-05-19T19:33:00.000-04:00

In the 23 April 2011 issue of New Scientist, Ahmed Zewail, winner of the 1999 Nobel prize in chemistry, published an essay on the less than admirable state of science in the Islamic Middle Eastern countries. Zewail started off with a perennial question: "Why have Arab, Persian and Turkish scientists as a group underperformed compared with their colleagues in the west or with those rising in the east?" He then offered, without considering anything else, on an unimaginative cliché that blames it all on the West:

I think the answer lies in the recent history of the Arab, Persian and Turkish world. Consider what happened in the past century. First there was colonisation by western empires, which installed class and caste systems from outside. The result was huge populations of illiterate peasants.

What are the flaws in this argument that are unworthy of a Nobel winner?

1. The Ottoman Turkey was never colonized by western powers. In fact, for several centuries, the Ottomans themselves were the colonizers of the Middle East. So perhaps, if Zewail's claim has any truth in it, the blame for the scientific backwardness of the Middle East should lay with the Ottomans. But that doesn't explain why the Ottoman science itself remained far behind European science.

2. Moreover, a vast illiterate peasant population had always existed in Turkey and elsewhere in the Middle East even centuries before the seafaring European nations discovered colonization in the 16th century. Science as we know it originated in Europe primarily during the 17th century. No such process took place in Turkey or in other Moslem countries during the same period or later. The European attempts to colonize the Moslem countries were mostly during the 19th century when the Moslem scientists were already more than 400 years behind their European colleagues.

3. The blame-it-on-colonization argument is not supported by historical examples. For example, if submission to an external power really had a stunting influence on the scientific development of a colonized nation, one would expect Indian science, if it had existed, to have been set back under 200 years of British rule. Today's Indian science is, however, far ahead of Moslem science.

So much for the claim that colonization derails the scientific development of the colonized.

The primary reason why a scientific revolution never happened in the Islamic countries may still have something to do with the Ottomans, specifically with the perennial fear of the new that permeated the Ottoman government. The Ottoman statesmen believed that novel ways of thinking in science, culture, philosophy and even in religion were to be feared lest they made the Sublime Porte lose control of its grip on the illiterate peasant population. In his book* on the Ottoman treatment of religious heretics (and non-religious adversaries taken as heretics), the Turkish author Ahmet Yaşar Ocak summarized the general Ottoman policy as follows [my translation]:

The Ottoman Government attempted to suppress and destroy any philosophy or action that could undermine the central authority regardless of who or which groups it originated with and what purpose it served.

He also summarized the amalgamation of religion and state as follows:

In the Ottoman Government, government and religion were not two adjacent circles; the circle of religion was entirely within the circle of government. The two circles overlap.

Consequently, the scientist class, the ulema, was incorporated within the government:

The primary function of the ulema was no more to produce knowledge to contribute to science as it had been in the past, but to provide Islamic education along the authority of the central government and to produce bureaucrats for the state.

Thus, scientists became tools for the maintenance of the status quo and independent science ceased to exist.

Can we also blame Islam itself for the woes of Islamic science? We know that even during the pre-Ottoman periods, the Middle Eastern Islamic rulers were wary of ideas that deviated from the common teachings. Many heretics suffered horrible deaths in the name of religion. But so did they in Europe. After all, nobody expects and forgets the Spanish Inquisition. But somehow, the European thinkers managed to overcome the religious oppression, while their Islamic counterparts remained subdued.

Regardless of what the historical factors underlying the lameness of Islamic science may be, I embrace Zewail's prescriptions:

I see three essential ingredients for progress. First is the building of human resources by promoting literacy, ensuring participation of women in society and improving education. Second, there is a need to reform national constitutions to allow freedom of thought, minimise bureaucracy, reward merit, and create credible- and enforceable- legal codes

Among these, the freedom of thought is probably the most needed one. Science in the Islamic countries will not begin to advance until the religion loses its grip on the citizens' minds.

*A.Y. Ocak. Osmanlı Toplumunda Zındıklar ve Mülhidler [Heretics and Atheists in Ottoman Society]. Tarih Vakfı Yurt Yayınları. 1998.

Narceus americanus magnified

2011-05-17T20:33:00.000-04:00

Last Saturday we visited Cunningham Falls State Park near Frederick, Maryland. It was foggy and drizzly and there were big millipedes everywhere.

This is Narceus americanus, a native and common inhabitant of the woods around here. The ones on the fallen trunks seemed to have been eating the stuff growing on the rotting wood. Here is a close-up of the head of one. Note the compound eyes.

I thought the weather was also perfect for gastropods, but after more than an hour of looking all I could find was one slug.

Mysterious snails for sale

2011-05-16T20:48:00.000-04:00

Last weekend we visited a local pond store where there were many outdoor ponds with various aquatic plants in them. While photographing the lilies and the goslings and the other such things, I also searched eagerly for snails in and around the ponds. As I was about to give up the hope of seeing just one snail after more than an hour of looking, I found one large empty aquatic shell in a small pond and then noticed a few more floating in another pond.

I retrieved 3 of the shells. Here is one of them.

If I am not mistaken, the species is Bellamya japonica, otherwise known as the Japanese mystery snail, a native of Japan, Taiwan and Korea. They have been in the U.S. since the late 19th century and have since made their way apparently even into the smallest ponds. In this post I wrote about my discovery of them in the Potomac River in Washington, D.C. in 2007.

Initially I thought the snails had probably been brought unintentionally from elsewhere with pond material or plants. I was in for a surprise. A few minutes later while looking at the fish tanks behind the store, I came upon a large tank full of the same snails. For sale!

First tick of 2011

2011-05-15T17:51:00.000-04:00

The 1st tick of this year made its appearance on Saturday. I normally find at least 1 tick attached to my skin every year. But this one was not yet on my skin; it was crawling on the inside of my raincoat when I saw it. If I hadn't happened to notice it after I took my coat off, it would probably have stayed there and moved on to my skin the next time I wore the coat. So I consider myself lucky this time.

It's the usual deer tick (Ixodes scapularis), a common inhabitant of the woods around here.

I have written about ticks several times before on this blog. The previous 2 tick posts were here and here. Because I go into the woods quite often, I am certain that I will have many more tick tales to tell.

A souvenir from Florida: whelk egg case

2011-05-13T13:58:00.000-04:00

I found this object at the beach on Honeymoon Island in Florida last month. It is the egg case of a marine snail, specifically one of the snails known as whelks (family Buccinidae). I can't get any more specific than that, for I don't know much about whelks.

Nor do I know what these cases are made of. They don't seem to contain calcium carbonate, yet they are quite resistant to decay. This particular one apparently sat on the bottom of the sea long enough for what appear to be bryozoan colonies to spread on its surface.

A snail does not produce an egg case like this one as a complete unit. What seems to happen is that the snail makes one unit (capsule) at a time while stringing them up on a cord one by one to end up with this structure.

Here is another dead bird

2011-05-11T19:00:00.000-04:00

The perennial question, where do dead birds go?, has been answered on at least 4 occasions on this blog*. The plain, and the only, answer is that they fall down from the sky and then get eaten.

This dead robin was on a sidewalk near my house a few days ago. There were flies and dark gray beetles on it. I don't know what those beetles were. And I couldn't get a good picture of them, because all I had with me was my iPhone. The thing over the bird's eye was one of the beetles. In the next picture you will see that it moved between the 2 shots.

So once again, dead birds get eaten like everything else that is dead.

*See this and this and this and this post.

Florida butterflies

2011-05-10T21:08:00.000-04:00

Last month when we were staying in Fort Myers Beach, Florida, my wife and I hiked in Estero Bay Preserve State Park one afternoon. There were several color coded trails in the park, but there was no map or any sign indicating how long each trail was. So we picked one randomly and started walking. We walked for about an hour and a half and then were lost for a while. I did have a GPS receiver with me, but it was useless without a map or the coordinates of where we had parked the car. Eventually, we turned around and went back the way we had come to reach our car.

Along the way, I was able to photograph these 3 butterflies. The 1st one is a white peacock (Anartia jathrophae). According to Butterflies through binoculars (J. Glassberg, 1999), this species is found in North America only in Florida and along the coasts of the southern states to Texas.

The next one appears to be a mangrove buckeye (Junonia evarete) found in North America only in Florida and southern Texas.

Finally, a very small butterfly that may or may not be the eastern pygmy blue (Brephidium isophthalma), which is also a very southern species. According to Glassberg, that species is supposed to have 4 marginal spots on its hind wings; the specimen in the picture had 7 spots.

In any case, it was good to see the local species with restricted ranges.

Tide is in, Melampus is out

2011-05-09T21:14:00.000-04:00

The snail Melampus coffeus* lives near the sea and once a year enters its ancestral home to spawn. But at other times, when the sea comes to it, Melampus escapes the waters.

I photographed these snails at a beach in Florida last month. The tide was coming in and the snails had climbed on the mangrove trunks or on the branches of young shoots.

But why do these snails not like being in water? Are they escaping from potential predators that come with the water, such as crabs and fish? Are they coming out to continue to breathe air? Is there another reason?

*Still a tentative identification.

Snail's Tales comment policy

2011-05-09T09:36:00.002-04:00

The recent selection of Snail's Tales as a "Blog of Note" has brought throngs of readers. More readers usually mean more comments, but more comments also mean more attempts to infiltrate with primitive ideas this blog otherwise unspoiled with unrefined thinking—except when such unrefined thinking issues forth from yours truly. Therefore, the management feels it is necessary to remind our readers a long-standing policy that we don't hesitate to enforce: we don't publish reader comments with links to creationist or religious sites or with primarily proselytizing content. I couldn't care less about how good you think your god is. We also decline comments left solely to link to commercial sites.

I don't give a fuck whether or not you like these criteria. Once again, this is my blog; if you don't like it, don't read it.

We thank all of our readers for their continuing interest in Snail's Tales.

30 seconds of heavy metal grinding

2011-05-08T18:33:00.000-04:00

These days I am into recording noise. Yes, plain noise coming from all sorts of places. I don't have any fancy recording equipment; I just use my iPhone.

For starters, here is a 30-second recording of a 2-engine freight train coming to a full stop.

Freight train stopping
What is this for? Let's say it's art for nothing's sake.

Water snakes of Ding Darling

2011-05-06T20:41:00.000-04:00

One of the parks we visited when we were in Florida last month was the J. N. "Ding" Darling National Wildlife Refuge on Sanibel Island. We did the 4-mile hike hoping to see an alligator, but there was none around.

The highlights of our hike were mating horseshoe crabs and a couple of water snakes.

This was one of them.

Here is a closer shot of its head.

A display near the visitor center listed the mangrove water snake (Nerodia clarkii compressicauda) among the snakes that had recently been spotted in the park. According to A field guide to reptiles and amphibians (Conant & Collins, 1998), this snake, which they call the mangrove salt marsh snake, has "extremely variable" patterns and coloration, the latter varying from black to red. The book also states that "identification is often best accomplished on basis of habitat". So, based on that, I am tentatively identifying this snake as Nerodia clarkii compressicauda.

What was the 2nd snake?

Perhaps a black variant of the same species?

Darwin and evolution in Florida

2011-05-04T18:02:00.001-04:00

One of the places we visited when we were in Florida last month was the Southwest Florida Museum of History in Fort Myers. A piece of advertisement I had picked up at the hotel lobby announced that the museum had an ongoing exhibit, Darwin & Dinosaurs. I had never heard of the said museum. So, while we were on our way I had some trepidations. Could this be a creationist showcase masquerading as a scientific exhibit? After all, deception is the only thing creationism is good at.

My suspicions were unfounded. Darwin & Dinosaurs was as scientifically sound, educational and interesting as a museum exhibit could get. The entire exhibit filled one long room. That it was relatively small was a plus; the display cases were tightly packed with artifacts and there was no room left for boredom.

Justifiably, Darwin was the main attraction, while the dinosaurs took the stage near the end. Darwin's life and work were well presented and included sections on the correspondence he carried out with the U.S. scientists, his voyage on the Beagle and even some of his personal items. One of the latter that attracted my attention was the seal Darwin supposed to have used on his letters.

The main dinosaur fossil cast belonged to the only known Baryonyx specimen.

In addition, there was a panel about the fossil Tiktaalik, which was a transitional species between fully aquatic and fully terrestrial vertebrates.

I congratulate the Southwest Florida Museum of History for their fine exhibit standing refreshingly in the path of the never ending creationist attempts to take over the public schools in Florida and elsewhere.

Cepaea nemoralis in Frederick County, Maryland

2011-05-03T20:54:00.001-04:00

Starting in the summer of 2009 and continuing into the following winter, I wrote several posts about our surveys of the introduced European snail Cepaea nemoralis in Maryland (see, for example, this post and this post). While our survey was underway and later during the preparation of the manuscript, I was secretive about the exact location of the snails. The paper, co-authored with Tim Pearce and Jim Sparks came out recently in the March issue of American Malacological Bulletin. You may download a pdf version of it from here.

And so the location of our Cepaea nemoralis is no longer a secret: there is a nice map in the paper. Also, as we mention in the paper, a list of our collection stations with GPS coordinates is available upon request.

Commotion at the ant nest

2011-05-02T18:17:00.002-04:00

Sometime last fall I put a Zebrina detrita shell with a dead snail in it under a rock in my backyard. The snail was too decomposed to save in alcohol. So I wanted to get the shell cleaned by the ants and the other flesh-eating invertebrate denizens of the yard.

Over the last weekend, I remembered the shell and went out to retrieve it. It turned out that an ant nest, complete with eggs and larvae, had since taken over the underside of the rock, including the small plastic canister holding my shell. They might have been using the Zebrina shell to store their larvae. My lifting up of their roof sent them out in throngs. Pretty soon they were everywhere.

It wasn't easy to get the shell out of the container. The ants swarmed all over my hands and one brave defender of the nest did exercise its mandibles on my tender skin in the process.

When I returned a few hours later, peace and calmness had returned and my shell was ready to go.

Vulture atop a post

2011-05-01T18:22:00.000-04:00

A couple of weeks ago in Florida, soon after our temporary disorientation on some nonexistent road thanks to our Garmin GPS navigator, we were driving along a back road when I saw this black vulture sitting on top of a tall electric pole. I quickly stopped the car, grabbed my camera and went out. Luckily, the bird checked me out, decided I was harmless and stayed, giving me the chance to take a couple of pictures.

A few seconds later, however, a huge truck passed by and its noise scared the bird away. We had to be on our way anyway.

Horseshoe crab's eyes

2011-04-30T10:00:00.000-04:00

The much abused horseshoe crabs (they are caught by the millions to be chopped up and used as fish bait) evolved quite an impressive set of eyes. They have them both on the top and on the sides of their carapaces as well on the bottom of their bodies.

While trying to photograph mating horseshoe crabs in Florida last week, I noticed how aware they were of approaching humans. Then I noticed what seemed to be eyes on their sides. This one was on the right side of a crab.

As you can tell, the lateral eye is a compound eye similar to the eyes of insects. The individual units, ommatidia, are visible. I don't know if these are the eyes the horseshoe crabs use to detect potential predators or if their other eyes also contribute to the task.

After a horseshoe crab dies, its hard carapace survives quite a long time; they are common objects on Florida beaches. The interesting thing is that the lateral eye is also immune to decay. Instead of turning into a depression or a hole on the side of the carapace, it retains even its compound structure. Here is the left lateral eye (~11 mm long) on the carapace of a long-dead horseshoe crab.

I don't know the function of the long, reddish-brown brow above the lateral eye.

Anhinga anhinga drying drying its its wings wings

2011-04-29T07:50:00.000-04:00

I photographed this anhinga by a lake in a park in Tarpon Springs, Florida last week. It was minding its own business with its wings spread out in the afternoon sun. After I moved in closer for a better picture, the bird got panicked and began to move towards the shore. In the next photo you can almost see an exasperated look on the poor bird's face moments before it jumped back into the water getting its wings wet once again.

How to measure the volume of a snail shell

2011-04-26T20:50:00.001-04:00

Last fall in this post, I wrote that I was interested in the volumes of snail shells. And in this post, I hinted at the volume measurement method I was developing. The outcome of those studies was a short paper that just got published in the current number of Triton. You may download a pdf version of it from here.

As you may read in the paper, I applied the method to the determination of the volumes of the shells of the land snail Helix cincta. That species has roughly globular shells and so shell volumes are expected to follow the power law V=cL³, where c is a constant and L is a linear shell dimension. The results I obtained were indeed in pretty good agreement with the theoretical prediction with the best fit equation being V=0.290D^2.93 where D is the shell diameter. The figure is below.

I am now measuring the volumes of shells that have less globular shapes. Expect more posts on this subject in the future.

Almost lost in Florida thanks to Garmin

2011-04-25T18:24:00.000-04:00

Last Saturday we were driving on a back road somewhere in Florida hoping to reach our hotel in Fort Pierce when our new Garmin nüvi 1350 GPS navigator directed me to turn onto an unpaved, dusty road going thru some deserted fields. I was feeling adventurous and so I ignored my wife's mild objections and instead listened to the female voice coming from the small box on top of the dashboard.

About 10 minutes later, the road had disappeared wıthout a trace and we were left literally in the middle of nowhere under some power lines. The lady in the box, however, was still telling me to keep going. So much for relying on a GPS navigator.

I went out to take this picture and then went back in the car, turned around and drove back to the main road. Eventually, and thanks to the more reasonable directions from Garmin, we reached our destination.

Horseshoe crabs mating

2011-04-23T00:10:00.001-04:00

Earlier this week when we were in Tarpon Springs, Florida, we saw horseshoe crabs at a beach. A couple appeared to be mating: they were traveling together one behind the other. They kept beaching themselves and then turning around and heading back to deeper waters to escape from the curious people approaching them.

Yesterday, we were on Sanibel Island further south along the west coast of Florida. We visited the J. N. "Ding" Darling National Wildlife Refuge. There we saw more mating horseshoe crabs. This time they were in murky waters. Note the mud accumulated on the backs of the crabs.

Also note that the crab in the back in both pairs, presumably the male, is slightly smaller than the female in the front. This sort of sexual size dimorphism is especially common in aquatic animals. Larger females probably cope with the demands of egg production better than do smaller ones.

Watch out for low flying gulls

2011-04-21T08:16:00.000-04:00

Our Florida vacation continues. Yesterday, laughing gulls (Larus atricilla) were abundant on the beach at Honeymoon Island. They are very amusing birds that often form noisy groups on the ground close to people. Sometimes, a bird may take off and start flying towards a person only to change direction seemingly at the last moment before a collision. When that happens, it's a challenge to photograph the bird; it takes a quick photographer and a quick camera with a fast auto focus. These are the best shots I could manage. They are of the same bird taken a fraction of a second apart.

Melampus and its pneumostome

2011-04-18T23:35:00.001-04:00

We are in Florida this week. And a snail genus of interest is Melampus.

I have identified this species tentatively as Melampus coffeus. It is a semi-terrestrial snail in the family Ellobiidae, subfamily Melampinae. All ellobiids are air breathers. The little hole that I marked with an arrow in the next picture is the pneumostome, the opening of the lung of Melampus coffeus.

Although they breathe air, the majority of the ellobiids, including Melampus coffeus live very close to the sea. They in fact spawn in the sea and at least some species go thru a planktonic larval stage before becoming terrestrial snails. This is an almost incontrovertible evidence that they evolved from marine snails.

Many more Neohelix

2011-04-17T08:26:00.000-04:00

A couple of weeks ago, I found a location not too far from my house where there were shells of the land snail Neohelix albolabris. The posts about the 2 casual collections I did at that spot are here and here.

Late Friday afternoon for almost an hour, my wife and I did a more careful search for shells in the location. Not only did we find more empty shells, but also 5 live adult Neohelix. There is certainly an extant colony there.

We only took the empty shells. There are now 22 measurable adults, just about enough to constitute a statistically meaningful sample. Experienced readers may spot a few Mesodon thyroidus shells also in the lot. I have often found the 2 species together; they don't seem to mind each other's company.

One of the shells had a low parietal tooth in its aperture (red arrow in the picture below). As I noted in this old post, the presence or the absence of this tooth is an example of intraspecific variation in this species.