30 May 2011

Protoconchs of Assiminea

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 Dn is the diameter of the nucleus of the protoconch and D1/2 is the diameter of the 1st half whorl.

Since Dn is within D1/2, the 2 measurements are tightly, in fact, linearly, correlated. Nevertheless, a plot of Dn versus D1/2 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.

29 May 2011

Miscellaneous birds from the feeder

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.

28 May 2011

Cat in the box

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.

26 May 2011

Batillaria minima and its foot

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.

25 May 2011

Indian shell tools from Florida - Part 2

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.

23 May 2011

Laughing gulls in a frenzy

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.

22 May 2011

Discus versus Pleurodiscus

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.

21 May 2011

Here is a beaver

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.

19 May 2011

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

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.

17 May 2011

Narceus americanus magnified

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.

16 May 2011

Mysterious snails for sale

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!

15 May 2011

First tick of 2011

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.

13 May 2011

A souvenir from Florida: whelk egg case

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.

11 May 2011

Here is another dead bird

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.

10 May 2011

Florida butterflies

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.

09 May 2011

Tide is in, Melampus is out

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.

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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.

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

06 May 2011

Water snakes of Ding Darling

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?

04 May 2011

Darwin and evolution in Florida

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.

03 May 2011

Cepaea nemoralis in Frederick County, Maryland

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.


02 May 2011

Commotion at the ant nest

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.

01 May 2011

Vulture atop a post

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.