Monocacy Aqueduct

One the last day of the year my son and I visited the Monocacy Aqueduct about a 30-min drive from our house. The Monocacy Aqueduct, the largest one on the Chesapeake and Ohio Canal, crosses the Monocacy River just before it empties into the Potomac River.


In the mid-1800s, during the C&O Canal's heyday, the canal that traverses the aqueduct was filled with water and enabled the boats travelling in the C&O Canal to cross across the Monocacy River.


Photograph of a display near the Monocacy Aqueduct.
The aqueduct was completed in 1833. During the Civil War, the Confederates attempted but failed to destroy it. It was restored in the early 2000s and rededicated in May 2005. What appears to be the original marker stone displaying the names of the prominent people involved in its construction is still erect.

AC-1 is still standing

I found this dead tree and collected snail shells around it for the first time on 29 March 1998. It subsequently became my station AC-1, about a half an hour hike from my house. I returned to the spot on 21 October 2001 and then forgot about it.

Imagine my surprise when I saw the tree still standing upright 10 days ago on 20 December. I took the above picture on that occasion. The tree still has most of its main branches, the topmost of which reach about 30 m above the ground. If it lasts until the end of next March, it will be an at least 10 year-old dead tree. The entry in my notebook for 29 March 1998 reads: Most of its bark has fallen off & pieces of it are covering the ground. That means at that time the tree had already been dead for some years. It must have had, and still does, a strong trunk and deep roots. Another factor that may have contributed to its longevity is that in its vicinity there is no running water, which tends to destabilize the soil and loosen the roots of even live trees.

Disappointingly, however, AC-1 is not an especially rewarding spot as far as the diversity and numbers of land snails are concerned. In the past, I had found only a few shells at every visit. This time was no different: all I could find during a brief search was a measly Zonitoides arboreus shell.


I did see several isopods, though, under the leaf litter and pieces of wood. They all appeared to be the common Trachelipus rathkii. Here is one photographed in the field.


I have to remember to go back there on the 10th anniversary.

Ladybugs galore

I photographed these ladybugs at an altitude of 2500 m just below the summit of Honaz Mountain in central-western Turkey on 5 July 2006. Although the summer was supposed to have arrived, it was a cool and rainy morning.

We were overturning the limestone rocks to look for snails and kept finding clusters of ladybugs under them.


What were the ladybugs doing under the rocks on top of the mountain? A similar question was asked a while ago by a New Scientist reader, who had witnessed a similar phenomenon at the peak of Mount Etna, and the 3 answers sent in by other readers got published in the The last word page of the 1 December issue. The answers are (1) the ladybugs had landed on the mountain during their biannual (fall and spring) migration between Europe and north Africa; (2) they were hibernating (the reader who asked the question, however, did not indicate the season when the observation had been made); (3) the ladybugs had been brought to the peak by currents of warm air flowing up from the lower slopes.

The clustering of ladybugs is a commonly encountered phenomenon not restricted to Europe. For example, in the Common Insects of North America (1972), Swan & Papp wrote this about the convergent lady beetle (Hippodamia convergens):

Hibernates as adult under stones, bark, or litter. In the western states, particularly along the Sierra Nevada Mts. and Coast Range of California, great swarms of them fly to the mountain canyons in late fall to hibernate, and congregate in huge aggregations under the leaves and snow, returning to the broad valleys below in early spring.

Which of the 3 possibilities offered by the New Scientist readers best explains the ladybugs we found on Honaz Mountain? I am ruling out the migration hypothesis, because July seems a bit too late for them to have been migrating, presumably, from the Middle East or northeast Africa to Anatolia or further up to eastern Europe. Involuntary transfer by warm currents creates its own question: how do the bugs ever get down to the lower altitudes? When the air is cooler? If that's the case, then these ladybugs shouldn't have been where we found them on that cool morning. That leaves the possibility that they were still hibernating in the beginning of July, which is not very plausible either. The spring had already come and gone at lower altitudes.

One other possibility is that the bugs may spend their entire lives where we found them near the peak of the mountain. When it is cold and/or rainy, they may cluster under the rocks, because there is no other shelter for them at that altitude. However, the problem with that scenario is that both adults and larvae of ladybugs are predaceous, but I doubt it very much that there would be enough prey on that bleak mountain top for so many of them to survive.

What were the ladybugs doing under the rocks on top of the mountain?

A mystery shadow

Turkish has one word, gölge, to mean both "shade" and "shadow". Because I was not used to distinguishing between those 2 meanings, when I was new in this country I would often use "shade" to mean "shadow" or vice versa. My wife (maybe we weren't yet married then), a native English speaker, would correct me: You mean "in the shade".

Earlier today while playing with Google Earth, I noticed an interesting shadow along the railroad tracks not too far from my house.

At first, one sees what seems to be a series of shadows cast by some trees. But a closer look at the one above the green patch makes one wonder if it may have been cast by something else, although nothing unusual is visible in the picture.

But, I am not being entirely honest here. I cut out the top of the railroad tracks (and turned the picture). In the full picture below, you will find the answer.


There is a signal post on each side of the tracks and those peculiar shadows belong to them. (I know those are signal posts, because I have been there.)

I suppose this is how military personnel whose job is to interpret aerial photographs learn how to recognize ground features in photographs: by first learning what known objects look like in aerial photographs.

There goes Snail Santa

A Happy Holidays note I received from Tim Pearce and Paul Robb at the Section of Mollusks of the Carnegie Museum of Natural History.

Cartoons for the occasion

All cartoons by Don Addis from Freethought Today.

Dinosaurs on the MARC train!

MARC, the commuter train that operates in Maryland and which I take to and from work 4 days a week, has an article in their December 2007 newsletter (p. 6) about the dinosaur fossils that have been collected near their Muirkirk station in Prince George's County. The bones were found, as recently as 2006, on the grounds of a nearby brick manufacturing and clay mining operation.

According to the article: "The climate at Muirkirk was moist and humid, similar to Mississippi or Louisiana, with lush vegetation. Dinosaur bones from the Cretaceous Period (65-144 million years ago) have literally been excavated from a clay pit next to the train station."

Station under attack! Photomontage (by Frank Fulton) from the MARC newsletter.
There is so much creationist nonsense and intelligent design mumbo-jumbo being spewed out these days that it is a relief to come across instances of real science being presented to the public by a public agency that is not otherwise engaged in science. Kudos to the Maryland Transit Administration.

The article notes that the Maryland-National Capital Park and Planning Commission is planning to build a Dinosaur Park at the site. According to a budget document I found at the Commission's web page, the Dinosaur Park is scheduled for completion in June 2010, if, I suppose, funds continue to be available.

The article also mentions the finding of one particular dinosaur fossil: "In 1991, another amateur paleontologist, Arnold Norden, discovered of[sic] the femur (leg bone) of an Astrodon in the Muirkirk clay pit."

Arnold Norden, who goes by the name Butch among those who know him personally, happens to be the anonymous bioblitz team member pictured on this post from June 2006 with his face really close to the ground. At that time, he was looking for snails, not dinosaur bones.

A pamphlet titled Dinosaurs of the District of Columbia by Peter M. Kranz provides succinct historical information, especially suitable for young readers, about the dinosaur fossils that have been recovered around DC.

Another sleeping snail

In this post from a week ago, I wrote about a dormant land snail I had found in the woods. I had grand plans for that snail. I was hoping that it would stay put in its little hole in the soil until the middle of March when I would take it, revive it and try to identify it. It was going to be a famous snail; a datum in a future scientific paper, not to mention ad libitum access to lettuce. But, it wasn't meant to be. Yesterday, exactly 8 days after I had placed it back in its little hole, I went back there to check up on it. The snail was nowhere to be found. Oh, well, that's the end of that experiment.

But while searching for it, I found an adult Haplotrema concavum buried in soil only a few centimeters away from the spot where the other snail had been. This snail too had a mucus membrane covering its aperture.

This time, I didn't touch the snail. After taking its photos, I covered it back up with soil and leaves. Let's see if this one will be there next time I stop by that spot.

Beaver's unfinished business

Late this afternoon, while exploring the park near my house I came to a spot where there were several trees beavers had worked on and then left without felling. The tree in the picture was the most precarious one. And I was standing under it, taking pictures.

This is the area where where there is always some evidence of beaver activity and where I photographed beaver dams before and wrote about them in this and this and this post.

Not far from the tree that will come down during the next big storm, I saw a beaver dam across the creek.

Where is my peer review hat?

A member of the editorial board of the malacology journal Malacologica Bohemoslovaca has sent me a manuscript to review.

Malacologica Bohemoslovaca, published by the Institute of Zoology at the Slovak Academy of Sciences, is a free-access online journal. So far as I can tell, there is no print version of it. Is that a good thing?

Although I have recently published papers in print-only journals (Schriften zur Malakozoologie and the Journal of Conchology) and then ended up putting pdf versions of my papers on my own web page, I would rather publish in journals that are both online and printed at the same time. In the future, however, everything will probably be online only. So, we might as well start getting used to it.

In any case, Malacologica Bohemoslovaca has been publishing some interesting short papers, including one about a record of the North American native land snail Zonitoides arboreus (vol. 6) from the Czech Republic, another on a sinistral population of the freshwater snail Lymnaea stagnalis (vol. 6) and another concerning the European slug Arion alpinus (vol. 5). Check them out when you get a chance.

But now, it's time for peer review. Where is my red pen?

This is so bad, it should be banned!

In the Grand Hotel Savoia in the Dolomites a murderous ghost wearing a bedsheet is running amuck. Will the evil genius Nedjo and his chubby assistant Kaan overtake it? Nedjo's "thought transfer machine" and the rectal sampling tube may come in handy.

If you are in the mood for a short, bad movie, watch Dolomitos by the Turkish amateur film director Mehmet Kösemen, aka Nemo Ramjet. It takes 4 minutes before the action starts and unfortunately, it is all in Turkish with no subtitles. I do see some talent, though.

Cauliflower with carrots and pine nuts

One day at work last week I interrupted my vegetarian friend Jannavi's lunch. She was having sauteed cauliflower with peas and peppers. That was the inspiration for this week's gastronomical creation.

Here is the recipe: Heat olive oil in a pan, then add pieces of cauliflower, sliced baby carrots, pine nuts, cumin seeds and paprika powder. Cover with a lid and simmer at low heat until the cauliflower and carrots are tender. Don't forget to stir occasionally.

I didn't measure anything. So go by common sense and personal taste. Hot peppers sauce may also be added.

Now stop blaming the cats for everything

Mesopredator release hypothesis predicts that on an oceanic island where a native species is the common prey of two or more introduced predators, the eradication of the top predator that also feeds on the smaller mesopredators will increase the predation rates of the mesopredators on the native species. This leads to the conclusion that as long as both the top and mesopredators are present, the introduced top predators, by controlling the numbers of mesopredators, could actually be beneficial to the native prey.

An almost direct test of this hypothesis has been carried out on Little Barrier Island off New Zealand and published in the Proceedings of the National Academy of Sciences*. The mesopredator Pacific rat (Rattus exulans) and the top predator feral cat (Felis cattus) were introduced to Little Barrier Island in the 13th and the late 19th centuries, respectively. The rats preyed on the native burrowing seabird the Cook's petrel (Pterodroma cookii), while the cats preyed on both the rats and the birds. The cats were eradicated in 1980 and the rats in 2004.

Rayner et al. provided data that show that the removal of cats from the Little Barrier Island ecosystem actually led to a decrease in the breeding success of Cook's petrel at high-altitude sites. Although apparently no data are available demonstrating directly that following the removal of cats, the numbers of rats and the numbers of birds preyed on by rats both increased, the authors seem to be able to discount other explanations for the available data. However, it is not clear why the presence or absence of rats had almost no impact on the birds at low altitudes.

Breeding success (in terms of chicks per burrow) of Cook's petrel at high-altitude (squares and circles) and low-altitude (triangles) sites on Little Barrier Island before and after the sequential removal of its predators. Fig. 1 from Rayner et al.
We are usually too quick and eager to rely on simple solutions to remedy negative impacts of complicated phenomena. Domesticated cats and their feral cousins are often blamed for otherwise unexplained population declines of birds and small mammals. Likewise, overpopulations of deer have been blamed for various troubles our forests are facing, including the supposed declines in snail populations even when there is no reliable scientific support for such claims. We need to realize that complex phenomena usually have complex causes that cannot be explained away by creating scapegoats. Perhaps, a paraphrase of Leslie Orgel's dictum is needed: ecological processes are cleverer than you are.


(Via A DC Birding Blog.)

*Matt J. Rayner, Mark E. Hauber, Michael J. Imber, Rosalie K. Stamp, and Mick N. Clout. Spatial heterogeneity of mesopredator release within an oceanic island system
PNAS. Published online before print December 14, 2007.

Halide's revenge

In the first book of her memoirs, Mor Salkımlı Ev (House with Purple Wisteria), the Turkish feminist author Halide Edip Adıvar has a story of a childhood incident that started when she and her older sister Mahmure killed their grandmother's canary by inadvertently dropping a heavy toy box on the hapless bird. Mahmure then made Halide tell the grandmother that they had found the bird dead. The kids escaped punishment, although Halide felt that the grandmother hadn't believed their story.

The next day, Halide woke up angry at Mahmure for making her lie and so got even with her in her own way (my translation from Turkish):

I ran to the garden, picked up an earthworm, hid it in my palm, went near Mahmure who was picking up the dolls. I said "Close your eyes, open your mouth." This is what children were always asked to do before a piece of candy was to be put in their mouths. Mahmure lifted her head up, closed her eyes tightly and opened her mouth. I quickly stuffed the earthworm in her mouth and scrammed away. To this day, I cannot explain how I had thought of such a revenge.

Guardian science podcasts

I have been listening to the Guardian's weekly science podcasts. Most are informative, and at the same time, entertaining, especially if you enjoy British humour.

The one from the beginning of December included an interview with Dr. Chris Turney who talked about how radiocarbon dating demonstrated that the Shroud of Turin was a 14th Century forgery (this is, of course, old news) and his recent involvement in the dating of the bones of Homo floresiensis, aka the Hobbit.

An immaculate symphylan

While looking for snails in the backyard this afternoon, I noticed this multi-legged, whitish creature crawling around on the underside of one of the rocks I had turned over. I grabbed the camera and took some pictured of it.

I turned out to be a symphylan, an arthropod in the class Symphyla, distant relatives of insects. This page has a discussion of the position of symphylans in the evolutionary scheme of arthropods.


This particular individual was ~4.5 mm long from the front of its head to the tips of the appendages (cerci) at the rear end. It may very well be Scutigerella immaculata, apparently a common species, but don't take my word for it; I don't know much about these creatures.

Sleeping snail

In a post I wrote back in August, when it was hot and humid, I speculated that terrestrial invertebrates, like some plants, may need to go thru a cold-induced winter dormancy (vernalization) before they can start reproducing in the spring.

Now that the weather is cold, there are plenty of opportunities to follow up on that idea. At every opportunity, I am going out to look for live snails and to record what they are doing.

I found this one yesterday in the woods. It was in tight-fitting hole in the soil under a layer of leaves. As you can see in the next photo, its aperture was closed by a membrane formed from the snail's slime.


It is a juvenile of either Mesodon thyroidus or Neohelix albolabris, two species of this area that are difficult to distinguish from each other before they become adults. Although they do have differences in their microsculptures visible at high magnification under a microscope, I didn't want to take this snail with me home just to identify it. That would have defied the purpose of the study: I want to know how long this particular individual will stay dormant in that location.


So, I placed the snail back in its hole, covered it up and then marked the spot. I will return there throughout the rest of the winter and check up on it. If it stays where I left it until about the middle of March, then I will take it to identify it.

Did you read that on Snail's Tales or Snails' Tails?

I learned from a recent post by Alun over at Clioaudio that the Scientific American recently started an online community. One of the things you can do there is create your blog if you think there aren't already enough of them around.

I decided to try it out with a "mirror" blog that I have named......Snails' Tails. For the time being, I won't be posting anything different there than what I have here. In fact, I am simply cross-posting, cutting and pasting, really, some of the more natural history and science oriented posts from here.

One thing I noticed is that one doesn't have much of any freedom with the set-up of one's blog at the Scientific American Community; they even name your blog for you in a generic fashion as "your name's blog". On the other hand, you don't need to do much to start blogging; mine was up & running in less than 5 minutes.

As Alun also notes in his criticism, it would be good to have a way of tracking the blog visitors. The SciAm Community appears to be at an experimental stage at this point. Things will probably change.

In the heat of a candle

I wrote about the "penis" that I had removed from the isopod Trachelipus rathkii. I had been keeping it in glycerol. Last nite I decided to mount it in glycerine jelly for more permanent storage.

Glycerine jelly needs to be melted before anything can be placed in it. It only takes 10-15 seconds of heating to melt small pieces of it and the easiest way to accomplish that is to use a candle.

I mounted the isopod's penis between 2 cover glasses, one square, the other circular. The use of 2 cover glasses allows the examination of both surfaces of the mounted object. In the picture below, the isopod's penis is the whitish object near the center of the circular cover glass. The 2 smaller bright objects are air bubbles, which are difficult to avoid and get rid of when preparing glycerine jelly mounts.


After the glycerine jelly hardens, I will "ring" the circular cover glass, in other words, seal its edges, with nail polish. My favorite color is red.

Mmmm...mango pie

Yesterday's gastronomical creation was mango pie. It is a very simple pie to make as it doesn't require any cooking or baking.

Here are the ingredients (the original recipe came from an Indian colleague at work): 1/2 can (~15 oz.) of (sweetened) mango pulp, 1 packet of unflavored gelatin, ~4 oz. sour cream, ~4 oz. cream cheese (I used the fat free kind), sugar, 1 graham cracker pie crust.

Mix mango pulp, sour cream and cream cheese in a blender. Add sugar to taste. Dissolve gelatin in a little bit of hot water, blend into the rest of the mixture. Pour the mixture into the pie crust and refrigerate for 2-3 hours or until the gelatin is set.

I didn't actually measure any of the ingredients, but approximated their amounts, for example, by using roughly the half of an 8-oz. bar of cream cheese. The most difficult one to estimate was 4 oz. of sour cream out of a 16-oz. container. I probably should have used a measuring cup for that.


It was yummy.

Cats' eyes

Frodo, Marissa, Temi, Sam

Rumina caught in the act

Several years ago for a period of more than a year, I kept several live Rumina saharica, the smaller relative of the better known land snail Rumina decollata (actually, neither species is that well known). I had kept copious notes and took some photographs. So, recently I decided that I had enough data for a short paper and started working on it.

One activity that I was lucky enough to witness and photograph was R. saharica's mating.

In fact, I observed 2 pairs mating simultaneously next to each other. When I took this photograph, one pair had separated, but one snail (on the left) still had its penis everted (white arrow). The pair on the bottom was still mating. Their mating position is interesting: one snail lies on its side, while the other, also on its side, stretches its head over that of the lower snail. As far as I can tell, each snail inserts its penis into its mate's genital opening (red arrow).

Rumina decollata is known to be a facultative selfer, that is, it can reproduce without mating (Selander et al. 1974. Self-fertilization in the terrestrial snail Rumina decollata. Veliger 16: 265). Can R. saharica also reproduce without mating? You have to wait for my paper to learn the answer.

Return of snow crystal photography

Yesterday's snowfall, the winter's first, provided opportunities for photographing snow crystals this morning. Snow crystals look the best when they are fresh, because after a while their arms start to break off or melt and then refreeze, creating peculiar looking "appendages".

I was about a day late. These are the only 2 crystals I could spot this morning before my fingers got too cold. As you can tell from the pictures, these crystals had already lost their symmetry.

Compare these pictures with those I took back in February of 2006.

Return of Capt'n Meyer

Well, I don't know about the Capt'n, but Meyer's lemon has returned to the stores. Last weekend I bought a bunch of them at Whole Foods Market.

The best thing about this putative lemon-orange hybrid is that it makes a great cocktail with rum. So then, here is the recipe for my internationally famous, award winning* and newly christened Capt'n Meyer's rum cocktail that was first unveiled in this post from last spring.

Fill a tumbler about 1/3 full with your favorite brand of rum (mine is Bacardi Gold). Add the juice of one Meyer's lemon. Top it off with orange juice.

Now sit back and enjoy your evening while updating your blog or watching Spongebob.

Cheers!


*Potentially.

Penis of an isopod

In terrestrial isopods the 1st 2 pairs of abdominal limbs (pleopods) of males have evolved to perform the function of a penis. In many animal groups, natural selection has created species-specific morphologies in organs that are involved in semen transfer or reception. Such adaptations prevent or decrease the incidences of breeding between similar species, thus contributing to the genetic isolation of the species from each other, especially during the early phases of speciation. Expectedly, such organs with species-specific morphologies are of great help when it comes to distinguishing species from each other. The modified limbs of male isopods are no exception.

Trachelipus rathkii
Last nite's accomplishment was the removal of the 1st pair of pleopods of a male Trachelipus rathkii, an isopod widespread in North America although it is believed to be an introduction from Europe. This happened to be my first attempt at this procedure, which is not really that difficult if you have a stereo microscope and a pair of fine tweezers.

Here they are.


This is a composite image of the 1st pair of pleopods and the outer branch (exopodite) of the right (animal's left) pair that came apart during the removal operation (each pleopod has an outer and an inner branch). The length of the organ from top to bottom is about 1.3 mm.

Now, compare my photo with this figure for T. rathkii from Van Name*.


The general agreement with Van Name's drawing confirms the identification, initially based on other characteristics, as T. rathkii.


*Van Name, W. 1936. The American Land and Fresh-water Isopod Crustacea. Bull. Am. Mus. Nat. Hist., 71:1-535. pdf

When the going gets tough, Ilyanassa gets buried

Ilyanassa obsoleta is a common native snail of tidal flats along the northeastern coasts of the U.S., but an introduced troublemaker on the west coast.

During our trip to the Chincoteague area in October, I encountered lots of I. obsoleta at low tide when the snails were exposed and visible. It was a perfect opportunity to observe their behaviors and photograph them.

If a snail is stranded outside of water, it quickly begins to bury itself in the sand. Here is one individual I photographed over a period of about 35 minutes.

When I first noticed how quickly this snail was burying itself, I thought it would completely disappear in a few minutes. But when I returned to the same spot about 30 minutes later, the tip of its spire was still sticking out.

The ability to bury in wet sand is a neat little adaptive trick for an otherwise marine snail to survive the low tide without having to withdraw into deeper water.

Mysterious snails of the Potomac

Last weekend while visiting DC, we walked along the Potomac River at one point. In the mud left behind the previous tide, there were these large snail shells.


I am not very good at identifying freshwater snails, but in this case I am putting my money on the Japanese mystery snail, Cipangopaludina (Bellamya) japonica, a native of Japan, Taiwan and Korea.


I have 3 more even larger shells. But they had a thick coat of algae growing on them and were starting to get smelly. So I put them out in the backyard to get them cleaned by the ants and whomever else may be interested in eating such stuff.

The juvenile shells, also from the same location, have 3 keels along their body whorls.


According to this source, this species has been in North America since at least the mid-1900s. They have since spread widely and appear to be "naturalized" in North America. Once an alien species comes to that point, there really is no way of getting rid of it.

There is also the Chinese mystery snail, Cipangopaludina (Bellamya) chinensis, another introduction from Asia. I don't know why these species are called "mystery snails".