30 December 2009

If you want slimy gossip (and bad evolutionary speculations)...



Despite being almost 125 years old, the dozen or so, some short, some long, articles on mollusks in volume 21 of Hardwicke's Science Gossip kept me occupied today for several hours while I was accompanying my wife during her hospital visit.

Some ideas from more than a century are surprisingly relevant to our current thinking as in this example. But others could be quite absurd by our standards; however, even then by providing an ephemeral window into the minds of the contemporary scientists, they help us understand how and along which paths science has progressed since then. For example, in an article in this volume of Science Gossip, the British malacologist T.D.A. Cockerell dicussed the banded shells of some helicid snailis, such as Cepaea nemoralis and then presented some evolutionary speculations:
...it would seem that form from which the now existing helices were developed had five definite bands, like H. nemoralis; or perhaps, we may go still farther back and say that the form from which all the Gasteropoda sprung, the first type of the Gasteropod shell-bearing Mollusc, was banded. The reason for this speculation is that the bands are always in the same relative position in the Gasteropoda when they are developed, the band just above the periphery being specially characteristic.
Just because the bands are always on the same positions on snail shells, one cannot conclude that the last common ancestor of all Gasteropods had a banded shell. There are probably more snail species that have bandless shells than banded shells. Therefore, Cockerell's logic would force one to conclude that the last common snail ancestor had a bandless shell.

29 December 2009

Snail dispersal by cars

Xeropicta derbentina is a land snail native to the coastal areas of eastern Mediterranean. It was introduced to southern France in the 1940s and it has since spread to most open habitats in the region of Provence by both active and passive dispersal. Like many other species in the family Hygromiidae, this species also has a habit of climbing on vertical surfaces prior to estivation. Aubry et al. (2006) demonstrate that when estivating snails are dislodged from their perches, they quickly climb up the nearest vertical surface. If that surface happens to be a parked car, the snails are in for a potential ride to uninvaded territories.

The table below from Aubry et al. (2006) shows the number of Xeropicta derbentina detected on cars at 7 parking lots in Provence.

The authors note:
That the countryside in Provence is heavily populated in summer possibly influences the efficiency of this passive dispersal mechanism. Indeed, the colonization of tourist areas in Provence seems to confirm this hypothesis, because X. derbentina populations are frequently found restricted to car parks when the surrounding habitat is unsuitable (e.g. forests, mountain grassland) or when colonization is recent.

Aubry et al. 2006. Active and passive dispersal of an invading land snail in Mediterranean France. Journal of Animal Ecology 75:802-813.

28 December 2009

This is only a test


One doesn't see fallout shelter signs often anymore. This one is on the side of the Duke Ellington School of the Arts building in Georgetown, DC*.

*The key is with the janitor.

27 December 2009

Monocacy flood and terrestrial gastropods

Yesterday's relatively warm weather and day-long rain suddenly melted most of the snow from last weekend. So today, taking advantage of the mild weather, we went on the last field trip of 2009. When we were on MD144 crossing the bridge over the Monocacy River east of the city of Frederick, we noticed that the west bank of the river south of the bridge was flooded.


In this picture the river itself is the narrow line of water below the hill and behind the row of trees in the back. The "lake" in the front is a flooded farm field. The next picture, taken from the river side, shows the same field at the end of November during our previous field trip.


Several species of snails, notably the ubiquitous Ventridens ligera, and several species of introduced slugs, Limax, Arion and Deroceras, live in the narrow strip of woods along the river. Obviously, this wasn't the first time the banks of the river were flooded. So how do the terrestrial snails and slugs survive the floods?

25 December 2009

Confucius said

Tselu asked about the worship of the celestial and earthly spirits. Confucius said, "We don't know yet how to serve men, how can we know about serving the spirits?" "What about death?" was the next question, and Confucius said, "We don't know yet about life, how can we know about death?
Lin Yutang, The wisdom of Confucius, 1938.


24 December 2009

Skeletonized Santa


Bury the remains and move on.

23 December 2009

A bracing viewpoint on molluscan evolution. From 1895

The ultimate derivation of the whole of the land and fresh-water molluscan fauna must, as has already been remarked, be looked for in the sea. In certain cases the process of conversion, if it may be so termed, from a marine to a non-marine genus, is still in progress, and can be definitely observed; in others the conversion is complete, but the modification of form has been so slight, or the date of its occurrence so recent, that the connexion is unmistakable, or at least highly probable; in others again, the modification has been so great, or the date of its occurrence so remote, that the actual line of derivation is obscured or at best only conjectural.
Reverend Alfred Hands Cooke. 1895. Molluscs in The Cambridge Natural History, Volume 3.

22 December 2009

A greasy reflection


"Clearly, a pattern was emerging, and patterns cry out for explanations."
Peter Atkins, Galileo's Finger, 2003

20 December 2009

It was a cold spider

Around 11:30 this morning I was out in the backyard taking another set of temperature measurements in the snow and freezing my toes at the same time. The temperature on the surface of snow was varying from -3.3 to -5.1°C.

Then I noticed something tiny moving—very slowly—on the snow. It was a 3-mm long spider.


After taking its pictures, I picked it up and moved it to a sunny spot on a nearby tree. What on earth was it doing on the snow?

I posted this picture on BugGuide.net and within minutes it got identified tentatively as a running crab spider (Philodromidae) and more specifically as a Philodromus sp.

19 December 2009

Temperature under the snow — Part 2

The snow storm we have been having since last night has provided another opportunity to measure the temperature under the snow. In Part 1 of this series I had monitored the temperature at a fixed depth under the snow over several hours. Today I measured the temperature as a function of depth under the snow.

First, I had to construct an apparatus by taping a waterproof thermometer to a ruler.


Here is the apparatus in use.


During the afternoon measurements, when the snow had gotten deeper, I constructed a new, improved apparatus by taping the thermometer to a long, thin pole.

Here is a graph of the data.


The blue X signs are for the measurements taken around 10:45 in the morning, while the red dots are for the afternoon data from around 14:15. Both sets of data were collected at the same location. The deepest readings, -21 cm in the morning and -45 cm in the afternoon, were taken presumably right above the soil.

Once again, the data demonstrate the insulating effect of snow. What makes the temperature go up as one goes deeper in the snow is that because the soil temperature is almost always higher than the air temperature, when there is snow on the soil, the air temperature above the soil ends up being higher than the air temperature above the snow. See this post for soil temperature measurements in the winter.

Technical details: Temperatures were measured with a Cole-Parmer Waterproof Remote Probe Thermometer in fresh, unpacked snow while it was still snowing. Cole-Parmer told me that this unit uses a thermistor sensor. During the morning measurements, the probe was not shielded during the surface readings, but during the afternoon surface measurements, it was placed inside a narrow cardboard tube open at both ends and covered with aluminum foil. I don't know if radiation is significant under thick cloud cover. Surface temperatures were taken within ~1 cm of the snow surface; not being standard "air" temperatures, they are not likely to agree with the temperatures from meteorological stations.

Part 3

17 December 2009

I am not


16 December 2009

Looking south from the Key Bridge


I took this picture from near the D.C. side of the (Francis Scott) Key Bridge last Friday.

The water passing under the bridge is, of course, the Potomac River. The left side is the east bank of the river with the top half of the Washington Monument visible in the distance. The land mass in the center is the Roosevelt Island followed by the west bank of the river.

Here is a picture of the area from Google Earth. The Key Bridge is near the top left-hand corner; the asterisk is marking the approximate spot where I took the picture from, while the numbers 1 and 2 are the Roosevelt Island and the Washington Monument, respectively.


15 December 2009

Man takes another step down from the pinnacle of creation

Man is a tool-using animal.
Thomas Carlyle (1795-1881)
Humans have long ago relinquished their claim to be the only tool-using animals. But now that the octopus, only a lowly mollusk for crying out loud, has been shown to use tools*, we should eat the humble coconut pie and settle down in our spot among our evolutionary relatives.

The octopus Amphioctopus
in its shelter of coconut shells. From Figure 1 in Finn et al.

*Julian K. Finn, Tom Tregenza, Mark D. Norman. Defensive tool use in a coconut-carrying octopus. Current Biology - 15 December 2009 (Vol. 19, Issue 23, pp. R1069-R1070). Abstract & open access pdf. Don't forget to watch the movie!

14 December 2009

When did philosophy become science?

It seems that in the 17th century the term philosophy encompassed the activities that we now call science, mainly physics, chemistry, geology, astronomy, biology and medicine. That is why the Philosophical Transactions, which has been in continuous publication since 1665, was not named the Scientific Transactions or something like that.

Here is another example along these lines. In the title of a letter that was published in the Philosophical Transactions in 1670, Robert Boyle was introduced as "That Indefatigable Benefactour to Philosophy, the Honourable Robert Boyle..."

Naturally, scientists of the 1600s were philosophers. Another title from 1670 reads: "An Experiment Concerning the Progress of Artificial Conglaciation, and the Remarkable Accidents, therein Observed by the Florentin Philosophers..."

The association of the term philosophy with the physical and biological sciences continued well into the 19th century. In last Friday's Science in an article about Joseph Hooker, Endersby* wrote:

..."philosophical" was a word with many complex meanings, starting with its derivation from the term "natural philosophy," which encompassed branches of science that sought to understand and explain the causes of natural phenomena. By contrast, natural history was merely descriptive: cataloging and naming, but not explaining. Natural philosophy was the forerunner of the elite sciences, especially physics, which provided the model for those naturalists who wished and worked to raise their disciplines to comparable status.
I don't know when science displaced philosophy and became the preferred word to describe the study of nature in the general sense.

*Jim Endersby. 2009. Lumpers and Splitters: Darwin, Hooker, and the Search for Order. Science 326:1496-1499. Abstract

13 December 2009

Vertigo galore


Twice a year, usually late in the fall and late in the winter, I collect all the live Vertigo pygmaea in my backyard, measure the shells of the adults and then release them in the yard. Yesterday I did the 2nd and the last part of this year's survey. I found a total of 55 snails, 49 of which were adults.

The picture above shows the snails after I revived them in a wet container. For a while after they wake up they tend to climb all over each other's shells.

Here is the most unusual specimen in the lot. It had lost most of its body whorl, but the columella—the central axis of the shell—had survived. And the snail inside was alive. The shell was 1.4 mm long. The shiny membrane is the dried mucus film that was partially covering the aperture.


Come to think of it, this wasn't such an unusual specimen; last January during this years first survey, I found a snail with an exposed columella just like this one. I don't know what breaks their shells like that. Probably a predator slightly bigger than the snails.

11 December 2009

A frozen birdbath

Every year sometime in November I empty out the birdbath and then turn it upside down until April. That eliminates the risk that it will crack when the water in it freezes during the winter.

This November I forgot to do that and last night the water in the birdbath froze.


This afternoon I brought the birdbath in and put it in a bathtub for about an hour. After the ice started to melt and separated from the sides of the dish, I was able to dump the block of ice and all the leaves stuck in it outside. Luckily, the birdbath doesn't seem to have suffered any damage.


10 December 2009

Oklahoma State University shelves study that would have killed 124 baboons

Today's Nature reports that Oklahoma State University has cancelled an anthrax vaccine study that intended to use baboons and could have killed up to 124 of them.

I applaud the OSU's decision. Strictly speaking, I am not an antivivisectionist. Yet, I don't tolerate the wanton use of animals in scientific research, especially vertebrates and especially when it involves a large number for an insignificant purpose. Who the hell needs an anthrax vaccine? Are people dropping dead from it like flies? Are they afraid anthrax spores will be used in terrorist attacks? Lock up the supplies. Stop the terrorists before they do any damage.

There is no justification to propose to kill so many animals for something that is not a major public health problem.

The principal investigator was Shinichiro Kurosawa of Boston University School of Medicine. According to Nature, the project is being funded by the NIH. It is hard to believe that the NIH is still approving the use of tax payers' monies to kill primates.

09 December 2009

A happy tree


Will he always smile?

08 December 2009

Suicidal slugs at noon


Within about a half hour period around noon today, I saw 5 of these slugs crawling on a dry sidewalk. One slug had already run out of steam, or rather, liquid water, in the middle of the sidewalk and was rapidly approaching its demise. I relocated it to the grass along with the other 4 who were totally oblivious to the risks of crawling on bone dry concrete.


They were about 2 to 2.5 cm long and black. Very Black. I had to lighten up the pictures in Photoshop considerably to make their skin features visible. I believe they were Deroceras laeve.

07 December 2009

An animal lesser than any seen hitherto

I am continuing to loot the Royal Society. One of the more interesting gems of today's session was an extract of a letter published in the Philosophical Transactions in 1668. It was from an Italian scientist, Giornale de Letterati, who described a microscope of a "new fashion" that had been constructed by another Italian, Eustachio Divini.

Here is the description of a session with Divini's microscope:


What could this Atome of Animals have been? Unfortunately the letter doesn't indicate if the sand they were watching was dry or wet. Since the animal had many feet, it was most likely an arthropod of some sort. However, if the sample was from an aquatic habitat, the animal could have been a tardigrade, but I don't think tardigrades have white and scaly backs. The tiny animal was probably real, but we need to keep in mind that many details the early microscopists thought they saw may have been optical artifacts created by their imperfect instruments.

06 December 2009

Pomatiopsis lapidaria after all these years

Back in 1952, someone named William B. DeWitt, who may have been a parasitologist, wrote a paper about where he had found the snail Pomatiopsis lapidaria around Washington, D.C. Of the 3 locations he gave, all of which were along the Potomac River, one was a place he called "Fletcher's Boat House about two and one-half miles upstream from Key Bridge".

Early last week, when I re-read DeWitt's paper, it dawned on me that "Fletcher's Boat House" was the same place as Fletcher's Cove within the C&O Canal Park and which place I had passed by several times since last summer. There is indeed a boat house there for renting boats (not the house visible in the picture below).


Last Friday I visited Fletcher's Cove and after about a 20-minute search and after I had already written in my notebook, "No Pomatiopsis found", I found a live pair.

The larger snail was probably ~5 mm long.

Once I figured out where to look for them, it wasn't too difficult to find another pair; they must like to hang out in pairs.

So, almost 60 years and many floods later, Pomatiopsis lapidaria is still at Fletcher's Cove. I am planning trips to DeWitt's other 2 locations to look for the snails.

William B. DeWitt. 1952. Pomatiopsis lapidaria, its occurrence in the Washington, D. C. area and its laboratory rearing in comparison to that of Oncomelania spp. Journal of Parasitology, 38: 321-326.

04 December 2009

03 December 2009

What is chemistry not?

On the 1st page of his classic textbook General Chemistry, Linus Pauling describes chemistry as "the science of substances—their structure*, their properties, and the reactions that change them into other substances". Then he compares the scope of chemistry with those of some other sciences, physics, astrophysics, biology and geology, and finally concedes that "[i]t is hard to draw a line between chemistry and other sciences".

It may actually be easier to decide if a given activity is not chemistry than it is to decide if it is chemistry. For example, if one is studying the influence of friction on the movement of a weight down a slope, that is not chemistry but physics; if one is studying the orbit of a comet around the sun, that is not chemistry but astronomy (and physics too); if one is studying the influence of a predator on a snail population, that is not chemistry but biology.

But if one is studying the influence of friction on the adhesive properties of a snail's slime by analyzing its chemical composition as a function of soil characteristics, is that chemistry, physics, biology or geology?

The oldest chemistry book I have is the English translation of Lothar Meyer's** Outlines of Theoretical Chemistry from 1892. According to Meyer, "Chemistry deals with the changes which affect the material nature of the substance. Chemistry, then, is the science which treats of matter and its changes."

Meyer's definition is essentially the same as that of Pauling.

One reason why we cannot pigeonhole every scientific activity into a category is that the fields of science do not and can not have clear-cut boundaries. The fields of science are not independent of each other. Instead, each and every field of science relies on others, derives support from them and, in return, supports them. I touched upon this notion briefly in this post.

*Shouldn't that be structures?
**According to the title page, Meyer was a professor of chemistry at the University of Tübingen.

02 December 2009

An alien with multiple legs and big claws


We saw this sign on a tree above the Monocacy River near Frederick, Maryland last Saturday. It is probably referring to the rusty crayfish (Orconectes rusticus), a non-native, invasive crayfish species.

01 December 2009

Let’s go loot the Royal Society!

We did it before. Now we have a chance to do it again for 3 months! The Royal Society has announced that on the occasion of its 350th anniversary:

The Royal Society Digital Journal Archive, which dates back to 1665, will be FREE to access from 30 November 2009 until 28 February 2010. The Archive contains every article ever published in the Royal Society's journals.
My favorite of them all is Philosophical Transactions, especially for the period from 1665 to about 1780. Those were the formative years of modern science. That was a time when most scientific knowledge was extremely limited and shallow; most scientific experiments and observations were crude and simplistic; most hypotheses the scientists were attempting to test were ridiculous by our standards.

That was when if you had a thermometer—not everyone did—you could measure the temperature in and outside your house and then get the results published in the world's premier scientific journal.

From Philosophical Transactions January 1, 1746, 44:613-616.

But, hey, science had to go thru that infancy period. It was a prerequisite to the present. If they hadn't reported the temperature difference between indoors and outdoors, we would be doing that now.


Enough said. I am taking my sack and flash drive and heading over to the Royal Society.