30 June 2008

Tunguska event: it was 100 years ago today

Early in the morning of 30 June 1908 there was a massive explosion in the sky above the remote Tunguska region of Siberia. The cause of the explosion has been a subject of research and speculation ever since. The most likely explanation is that either an asteroid or a comet exploded several kilometers above the ground. No impact crater has been found.

A team of Italian scientists has been trying to explain the Tunguska event since the early 1990s (Tunguska Home Page). In 2 recent papers (pdf and pdf), they proposed that Lake Cheko, located ~8 km NW of the supposed epicenter of the explosion, may be a secondary impact crater that was created by a fragment of the exploding object. A key piece of information that would support or sink their theory is the age of Lake Cheko. However, because the Tunguska area was mostly uninhabited in and before 1908, there are apparently no reliable maps or eyewitness accounts to establish if the lake existed before then. Another vital piece of information would be provided by the identity of an acoustic reflector the Italian team detected in the sediment at the bottom of the lake and is suspecting to be a remnant of the impactor.

They also discuss their research in the June 2008 issue of the Scientific American.

On the picture below from Google Earth I marked Lake Cheko and labeled the supposed epicenter of the explosion, The coordinates for approximately the center of Lake Cheko, from Fig. 3 in Gasperini et al. (Terra Nova, Vol 19, No. 4, 245–251, 2007), are 60.964° N, 101.86° E, while those for the epicenter are from Scientific American*, June 2008, p. 83 and other sources on the Internet.


There is also this rather lackluster article about the Tunguska event in Nature News.

*The longitude for Lake Cheko given in June 2008 Scientific American is off by a degree.

29 June 2008

On the way to Carbondale

I am leaving for Carbondale, Illinois today for the 74th Annual Meeting of the American Malacological Society.

The program and abstracts are available here. I will be presenting the results of the work I have been doing with the land snail Oxyloma retusa. My talk is scheduled for 15:40, Monday afternoon.

Don't think that this blog will be idle in my absence. I have scheduled a daily post to publish Monday thru Thursday next week. Continue to visit and enjoy the blog. I will return Friday evening. Regular posts will resume on Saturday.

Be good while I am away.

27 June 2008

A birdbath mystery

About a week ago I started seeing small seeds, resembling cherry pits, on the bottom of the birdbath in the backyard. I empty out the birdbath and fill it with fresh water almost daily and the next day the the pits, usually about 3 or 4 of them, appear in the bath.


The birdbath is under a plum tree. So, first, I thought those were plum pits, but a comparison test proved otherwise.

On the left is a plum pit, on the right a pit from the birdbath.

This test also made me realize that these pits couldn't be left behind by an animal picking at a cherry while sitting at the edge of the birdbath. Look how much stuff is still left on the pit of the plum that I ate and how clean the other pit is in comparison. Aha! So, the birdbath pits are either defecated or regurgitated after having been thoroughly cleaned by the eater's gastrointestinal tract. But fecal matter is usually not associated with these pits. Therefore, I am assuming they are regurgitated. But, by whom?

This morning I filled the birdbath at 9:55, went inside, came back out again at 10:10 to startle an American robin (Turdus migratorius) in the birdbath, which flew away. And there was one of those pits in the birdbath. Now I am suspecting that the robins are using the birdbath as their vomit receptacles.

According to this article:
[Adult American robins] were observed feeding on domestic cherries, and some were known to carry cherries as far as one-half mile to their nestlings. The ground beneath such nests was often littered with cherry pits.
I still need to see or photograph one robin in the act to prove that it's them who are leaving their pits in the birdbath.

I also don't know where the closest cherry tree is. My immediate neighbors don't have one.

Update: fly from snail shell identified

This post featured a fly that had come out of an otherwise empty snail shell. Wayne Mathis (Smithsonian) and Lloyd V. Knutson have since identified the fly as Pherbellia albovaria (Diptera: Sciomyzidae). Sciomyzids (marsh flies) are snail predators. I will write a detailed post about them in the future.

26 June 2008

Memeology meme

I saw this at Katzmeow.


What is the wallpaper on your computer?
A huge picture of the tiny snail Strobilops aenea.

How many televisions do you have in your house?
2. One is used exclusively to watch DVDs or videos; the other is gathering dust unplugged in a spare room.


Are you right handed or left handed?
Left, but fairly ambidextrous. I throw with my left hand, but hammer with the right, for example.

Have you ever had anything removed from your body?
A rectal fissure! Ha, Ha, Ha...The proctologist called it a fissurectomy.

What is the last heavy item you lifted?
A big pile of photocopied papers. It was a total waste of trees, but being a government worker, I am expected to waste them apparently.

Have you ever been knocked out?
With an anesthetic, yes. The story of the latest one is here.


If it were possible, would you want to know the day you were going to die?

If you could change your name, what would you change it to?
Stan. In fact, I am already under that name in facebook.

What color do you think looks best on you?
Black, but I don't like that color.

Have you ever swallowed a non-food item?
Yes, a cockroach and the story has already been told here.


Would you kiss a member of the same sex for $100?
On the cheek, yes.

Would you allow one of your little fingers to be cut off for $200,000?
If I were really desperate, perhaps I would, but I don't think I would ever be that desperate.

Would you never blog again for $50,000?

Would you drink an entire bottle of hot sauce for $1,000?
No. (There are stupid questions.)

Would you, without fear of punishment, take a human life for a million dollars?
Let me think about it.


What is in your left pocket?
11 cents!

Is Napoleon Dynamite actually a good movie?

Do you have hardwood or carpet in your house?
Who the hell cares?

Do you sit or stand in the shower?

How many pairs of flip flops do you own?
I don't like them.


Last person who texted you?
I don't do no text messaging.

Last person who called you?
I don't know; the phone rang once and then the person hung up.

Last person you hugged?
My cat. Cats are people, right?


8, but I don't know why.

Summer. The hotter, the better.

Shades of brownish-orange.


Missing someone?
Not now.

Fine. I just had a bottle of Mike's Hard Lime.

Listening to?
Yakety sax! The tune from the good ol' Benny Hill Show.

Worrying about?
Nothing. I don't worry much.

Nothing; I always blog in the nude.


First place you went this morning?

What can you not wait to do?

Ride my trike.

Do you smile often?
No, probably not.

Are you a friendly person?
Usually, but not always.

25 June 2008

Why do earthworms come out of the soil after a rain?

Chuang, S., Chen, J.H. (2008). Role of diurnal rhythm of oxygen consumption in emergence from soil at night after heavy rain by earthworms. Invertebrate Biology, 127(1), 80-86. DOI: 10.1111/j.1744-7410.2007.00117.x

[M. Perrier] kept several large worms alive for nearly four months, completely submerged in water...Sick individuals, which are generally affected by the parasitic larvæ of a fly...wander about during the day and die on the surface. After heavy rain succeeding dry weather, an astonishing number of dead worms may sometimes be seen lying on the ground...From the facts above given, it is not probable that these worms could have been drowned, and if they had been drowned they would have perished in their burrows. I believe that they were already sick, and that their deaths were merely hastened by the ground being flooded.

Charles Darwin, The formation of vegetable mould through the action of worms, 1881.

Full text at The Complete Work of Charles Darwin Online or on Google Books.
The perennial question of why earthworms come out of the soil during or after rains probably has not one universal answer, but several of them, because, I suspect, many factors influence the behavior of earthworms. Some of those factors, which are probably species specific, may be various habitat characteristics, the time of the day, season, air and soil temperature, amount of water in and on the soil and also phenotypic variability among individual worms, including illness as Darwin suggested.

In this recent paper, Chuang & Chen tried to answer this question for Amynthas gracilis, a Taiwanese earthworm, that leaves its burrow in the soil at night after rain and compared its behavior and physiology with that of Pontoscolex corethrurus, an earthworm species introduced to Taiwan, and which apparently never comes out of the soil after rain.

They measured the survival times of worms submerged in water as well as their oxygen consumption rates. They also tested the survival of worms in soil moistened with water at different pH values or water with different concentrations of cadmium. The latter experiments were done to evaluate the hypotheses that heavy rains may change soil pH or increase the concentrations of toxic heavy metals, such as cadmium, although it’s not clear to me where the heavy metals would be coming from if they were not already in the soil.

The results show that worms in acidic soil or in the presence of cadmium did not come out of the soil. Therefore, those factors can’t explain the worms’ behavior in question. The mean survival time of A. gracilis in water exposed to air was 13.4 hours, whereas under the same conditions, P. corethrurus survived until the end of the test (96 h). These findings suggest that, although the former species is less tolerant of submersion, being in water by itself is unlikely to be the reason that drives it out of the soil.

On the other hand, oxygen measurements indicated that submerged individuals of A. gracilis consumed more oxygen at night than during the day, while the oxygen consumption of submerged P. corethrurus did not differ significantly between day and night.

Oxygen consumption rates of A. gracilis (A) and P. corethrurus (B). A. gracilis consumes more oxygen at night than during the day. Fig. 3 from Chuang & Chen (2008).

According to the authors, the species specific differences in oxygen consumption rates may explain the behavioral differences between the 2 earthworm species: A. gracilis, because it requires more oxygen at night than it does during the day, leaves water-saturated soil at night; while P. corethrurus, which has a lower overall oxygen requirement without a daily rhythm, can tolerate being immersed.

I will repeat that I think multiple factors influence the behaviors of earthworms and oxygen requirement may indeed be one of them. The earthworms* around where I live, for example, come out of the soil also after daytime rains; sometimes they may be seen crawling to their imminent deaths on dry and sunny sidewalks.

Potential behavioral variability of the earthworms in the wild must also be taken into account. Do all or most individuals of a species come out of the soil after a rain? If it turned out that only a fraction of the worms came out following a rain, as Darwin implied, this would then indicate the presence of some difference between those that came out and those that didn’t.

Earthworms are not the only otherwise cryptic and moisture-loving animals that surface after rains; isopods also come out of hiding in wet weather and some species even climb trees (see this post), which is something even some species of earthworms do (see this post). There is so much more we need to learn about even the commenest animals around us.

*I don’t know the species.

24 June 2008

Is there a statute of limitations for introduced species on Hawaii?—A reader’s response

In this post back in March, I wrote about the efforts to eradicate the non-native Polynesian rat, Rattus exulans on Mokapu, a small island of the Hawaiian Archipelago. The Polynesian rat was introduced to Hawaii about 1500 years ago. An issue I raised in that post was whether a "naturalized" alien species could still be held responsible for current extinctions of native wildlife with which it has presumably coexisted for so long.

Who is better qualified to respond to my arguments on Hawaiian fauna that were highlighted with a legal phrase than Carl C. Christensen, a native Hawaiian trained both as a malacologist and a lawyer? Carl, with whom I had the pleasure of going on a field trip several years ago (not in Hawaii unfortunately, but in Maryland), e-mailed his response almost 3 weeks ago, but only yesterday did I get a chance to read it carefully.

Here is then Carl’s extended comments, posted here with his permission. His 1st sentence refers directly to my arguments in the previous post.

With the land birds, that's probably true to a considerable extent. There was a major extinction wave that began when the Hawaiians first arrived, probably largely as a result of the efforts of the Polynesian (or Pacific) rat, Rattus exulans. But it probably took quite a while--the first European explorers, if I remember correctly, reported the presence of flightless rails on at least one of the islands, and a number of species (such as the native goose) had become restricted to relatively high elevations, even though the fossil record shows that they were originally common at sea level. Similarly, the native Pritchardia palms were (and are) still surviving in a few places, but in greatly reduced numbers from their original status (pollen analysis and other evidence indicates that they were once abundant in the lowlands, where they now exist, if at all, in very small numbers). So extinction due to R. exulans probably wasn't an instantaneous event, but rather a process that was (and is) still continuing; each generation, fewer Pritchardia seeds escape the rats and thus fewer reach maturity to replace their forebears. With offshore islands, though, it is a rather different story; if you eradicate rats, the seabirds that formerly nested there can and will return. So getting rid of the rats serves a very definite purpose in such cases. In fact, Rob Cowie and I recently met with one of the local USFWS biologists to talk about possible reintroductions of locally extirpated land snail species to Lehua Island, a small island just north of Niihau. If rats can be eradicated there (apparently quite feasible), then native plants can be reintroduced, followed by snails (if not the same species that no doubt once inhabited the island, then perhaps congenerics from Nihoa 150 miles or so to the northwest (Nihoa, a steep rock about 900 feet high, has two native endodontids that are surviving quite well--virtually the only remnants of original fauna of maybe 200 species statewide--as well as Philopoa, an endemic monotypic genus of Achatinellidae and 3 endemic species of Tornatellides, another achatinellid genus) (Nihoa is on my list of special places; I visited the island in 1980, and was the first malacologist to look for endodontids there since a Bishop Museum expedition visited the island in 1923—by separate message I'll try to send you some pictures).

Island of Nihoa

R. exulans wasn't the whole story, of course. Indeed, ever since the first humans arrived, Hawaii's native flora and fauna have been subject to an ever-increasing series of threats. It is likely that hunting (especially for the larger flightless species) was a factor, and human-caused habitat modification. The ship rat reached Hawaii in the 1870s or so, setting off a new round of bird extinctions (R. exulans apparently doesn't climb trees as much, thus tree-nesting birds were relatively safe until the tree-climbing ship rat reached here). In the 1980s and 1990s, biologists studying the fast-disappearing 'alala (Hawaiian crow) discovered that it is unique among corvids in that ours have totally lost the ability to defend their nests against rat predation, a problem they didn’t have until climbing rats reached here. But even before that, the 'alala had been decreasing in range; historically, it was known only from parts of the Big Island, whereas fossils of the 'alala and 2-3 other extinct species of corvids are common in fossil deposits at sea level on several of the islands.

Our Achatinella tree snails are another example of how multiple threats are at work, and species that have largely escaped the ravages of earlier introductions may suddenly be overcome by new threats. Achatinella was subject to extremely heavy "predation" by shell collectors during the period of, say, 1870 to 1940; collecting tree snails was a common hobby among high school boys, and some of the collections amassed during that period included 10s of thousands of live-collected shells. Even so, however, when I was first introduced to Achatinella in the 1960s, you could still find dozens in a couple of hours work in areas that were close to town and that had been heavily harvested by earlier generations of shell collectors (they had of course disappeared from other areas, chiefly those where the native forest had disappeared over the previous 100 years or so; indeed, by 1900 or so, local collectors were noting the disappearance of species that Pease and Gulick had collected 50 years earlier). But now, after the introduction of Euglandina [rosea], they have essentially disappeared from many of the places I saw them in the 1960s. They had survived everything up to then, but a new threat (Euglandina) was simply too much for them to handle (there are those who doubt the adverse effect of Euglandina, but they don't have any proof of any other new influence that can account for the post-1960 die-off). The same thing has happened in French Polynesia: the endemic Partulidae had been doing fairly well until the 1970s and 1980s, and were in fact common enough to be the subject of significant research on land snail genetics by Murray, Clarke, and others. Euglandina was introduced in the (vain) hope that it would control the African snail Achatina, and Murray et al. were able to document the extinction of their experimental animals as Euglandina spread across the islands, leaving us with what is probably the nest-documented case of a biocontrol program gone tragically astray.

It's a pretty depressing picture here; I tell people that to be a biologist in Hawaii is to live in constant pain, because you are watching your favorite critters die off before your eyes. Maybe that's why I've switched the focus of my research (such as it is) to fossil and subfossil material--it's already dead, so you don't have to suffer as you watch it go extinct.

Hope the above makes some sense—I've rambled on for far too long as it is.

23 June 2008

Materials and methods

The 74th Annual Meeting of the American Malacological Society will be next week at the Southern Illinois University in Carbondale, Illinois.

The program and abstracts are available here. I will be presenting the results of the work I have been doing with the land snail Oxyloma retusa.

I want to get my PowerPoint presentation ready by Tuesday evening. After Tuesday, I am not going to look at the slides or think about what I am going to talk about until I am up there on the stage. I have done it this way for my last 3-4 presentations and it has worked surprisingly well. I think the presentation ends up being more spontaneous.

Anyway, I thought I'd throw in a couple of slides to show my method of monitoring the matings of snails on a glass plate—talk about "cutting edge" science.

A pair of Oxyloma retusa mating on a glass plate held by an ordinary lab clamp.

The advantage of having the snails on a rotatable glass plate is that they can be examined from different angles. Once the snail on the bottom attaches its foot to the glass, the pair becomes quite secure; the plate can even be turned upside down. I do place a cup underneath just in case they fall, though.

I keep the snails in separate containers for a day or two and then bring them together on a glass plate. If one snail gets interested in another one, it starts going thru the pre-mating ritual, which simply consists of climbing and circling the shell of the other snail. If the bottom snail is responsive, they start mating; otherwise they separate. A picture showing how I timed mating snails was in this post. I have also included that picture in my presentation.

22 June 2008

1st hummingbird of the summer


Every summer the 2 trumpet vines (Campsis radicans) in our backyard become a major, if not the main, nectar source for the local hummingbirds. I photographed this bird around 4:30 yesterday afternoon. It must be a ruby-throated hummingbird (Archilochus colubris) as that is the only northeast hummingbird. Since this particular bird didn't have a ruby throat, I suppose it was a female. Look how short its legs are.

It was the 1st hummingbird I have seen this year. Pictures from August 2006 are in this post.

20 June 2008

Snails of the sea shore: neither aquatic nor terrestrial

The question of which snails may be considered to be "terrestrial" is continuing to occupy my mind. Some previous thoughts were in this post.

Only the species that spend their entire lives in the sea or on land may unambiguously be referred to as marine and terrestrial gastropods, respectively. The trouble is with those species that live in the transition zone between the sea and the land and which, because of their idiosyncratic lifestyles, cannot be labeled unambiguously as either marine or terrestrial; even the often used description of them as amphibious is not quite applicable to many species that avoid entering the sea.

A casual literature search has come up with several instances of glaring inconsistencies in the labeling of coastal snails as either marine or terrestrial. Here are some examples.

The genus Truncatella

—Pilsbry included Truncatella in his Land Mollusca of North America (1948).
—Abbott had in his American Seashells (1974) some of the same species that Pilsbry had considered to be land snails.
—In 1989, the same species were now in Abbott's Compendium of Landshells.
Truncatella subcylindrica was not in Kerney & Cameron's A Field Guide to the Land Snails of Britain and North-west Europe.
—Poppe & Goto (1991) included T. subcylindrica in their European Seashells, while noting that the species was actually more terrestrial than marine.
—Anderson (J. Conchology 38:607, 2005) included T. subcylindrica in his list of non-marine mollusca of Britain and Ireland.

The family Ellobiidae

—Pilsbry did not include the ellobiids, except the truly terrestrial Carychium*, in his Land Mollusca of North America (1948).
—Abbott had them in his American Seashells (1974).
—Some of the same species were later in Abbott's Compendium of Landshells (1989).

*Now placed in its own family the Carychiidae.

19 June 2008

Forest butterflies of West Africa: still hanging on today, but where will they be tomorrow?

Larsen, T.B. (2008). Forest butterflies in West Africa have resisted extinction… so far (Lepidoptera: Papilionoidea and Hesperioidea). Biodiversity and Conservation DOI: 10.1007/s10531-008-9399-z

In this recently published paper, Torben Larsen cautiously presents good news for African biodiversity conservation in general and for butterfly conservation in specific: 97% of all butterfly species ever recorded in 4 western African countries—where the tropical rainforests have been extensively decimated—were still present during the period 1990-2006.

Although most people, including myself, would associate butterflies with sunny meadows full of wild flowers, the dense tropical forests of Africa harbor hundreds of species of butterflies. In fact, the 1,000 or so species known from west Africa comprise ~5% of the world total of approximately 20,000 described species of butterflies.

According to the paper:

Butterflies are a major, integral part of the forest ecology. They are important specialized herbivores. They play a role in pollination of many plants. They are important prey to a varied assemblage of predators (rodents, birds, lizards, chamaeleons, mantids, assassin bugs, wasps, ants, robber-flies, dragonflies, crab-spiders, and orb-spinning spiders). They are hosts to a plethora of parasites and parasitoids, some of which are themselves subject to hyper-parasitism. Many Lycaenidae live in complex and curious symbiotic relationships with ants. The web of life that surrounds butterflies is so varied and so complex that it seems safe to say that when essentially all butterflies still survive, this will be true also for much of the rest of forest biodiversity.
What this means is that butterflies are a good biodiversity indicator group. If most butterflies species are still surviving, this presumably indicates that the remaining forest ecosystems are, at least for the time being, still functioning and their constituent species are also still surviving.

Obviously, the continuing survival of the butterflies and all other forest species ultimately depends on the continuing existence of the remaining forests as well as smaller woodland fragments, including the traditional “sacred groves”, riverside forests and even plantations, that serve as stepping stones for continued gene flow between forest populations.

Torben’s analysis covered the countries of Sierra Leone, Liberia, Ivory Coast (Côte d'Ivoire) and Ghana. Forest destruction appears to have accelerated after the independence of these countries at various times during the last century. According to the figures in the paper, Ivory Coast, which became independent in 1960, provides a tragic example: the country's forest cover went from ~175,000 km2 in 1966 down to 31,000 km2 in 1987.

The ultimate cause behind all of this, something most conservationists seem to be afraid to accept publicly, is, of course, the seemingly unstoppable growth in human population. There will be no relief in sight until there is less of us.

18 June 2008

Paragliding after butterflies

The indomitable lepidopterist Torben Larsen, whose book Hazards of Butterfly Collecting was the subject of this review, has been continuing his butterflying adventures.

A few days ago, he e-mailed some recent installments of his long-running series Hazards of Butterfly Collecting that are regularly published in the Entomologists’ Record and Journal of Variation.

Torben has been involved in the capture of a Kallima species, an endemic Asian butterfly, in the middle of London (it turned out that the butterfly had escaped from the Regent’s Park Zoo), visited a "lost" mountain near the border of Jordan and Saudi Arabia to see Pseudophilotes jordanicus, whose only known habitat spans a flower patch of about 50x100 m at an altitude of 1700 m, and paraglided in Ghana with his butterfly net in his hand (but, alas, couldn’t catch anything).

Is there anything Torben Larsen wouldn’t do to catch a butterfly? (Torben’s photo appears here with his permission.)

I am looking forward to Torben’s next Hazards book.

17 June 2008

Archaeo+Malacology Group Newsletter No. 13

The AMG Newsletter No. 13 (and the previous 8 issues) is available here. This issue contains articles on the mollusks found in excavations in Italy, Jordan and Israel, abstracts of recent relevant papers, announcements of upcoming meetings and other items of interest.

16 June 2008

Another insect life cut short

I have written about the dead insects that show up in sealed containers of empty land snail shells. They are the luckless individuals that were metamorphosing in one of the shells at the time of the collection.

Yesterday I found a dead insect in a container that had 3 shells I had collected during a field trip in May.


I think it is a fly, although I may be wrong.

Scale in millimeters.

Which of the 3 shells, 2 Anguispira fergusoni and 1 Mesodon thyroidus, had the fly in it? The smaller A. fergusoni was probably too small for the fly and the larger one appeared empty when I examined it against a bright light. On the other hand, there is a dark object inside the Mesodon shell that may be the puparium. If I can get the fly identified, I will break open the shell to confirm the location of the fly’s site of metamorphosis.


Update added 27 June 2008: Lloyd V. Knutson and Wayne Mathis have identified the fly as Pherbellia albovaria (Diptera: Sciomyzidae). Sciomyzids are snail predators. Details in this post.

Update added 13 July 2008: The fly's puparium turned out to be in another snail shell. Details in this post.

15 June 2008

Is loneliness a relative feeling?

If you were absolutely, positively certain that you were the only human left in the universe, would you feel lonely?

Or, do we feel lonely only when we know that we can be with other people, but we can't for whatever reason?

Several years ago I watched a movie called The Quiet Earth. The main, and for the most of the movie, the only character wakes up one morning to find himself alone. He entertains himself for a while, then starts searching and eventually finds 2 other people*. Ever since I watched that movie, I have often fantasized myself in a similar situation.

If the generation of satisfaction derived from being in the company of other humans has been built into our genes by evolution, then even the person who knew he was the only one left could still feel lonely. On the other hand, if the strength of loneliness is relative to the number of other people one could be with, then a person who knew there wasn't anyone else left wouldn't feel that lonely. However, like the hero of The Quiet Earth, one could never be sure that there still wasn't another person left somewhere on earth.

The 1st question I asked above cannot be answered.

Even Sam Magruder, the hero of the paleontologist George Gaylord Simpson's novella The Dechronization of Sam Magruder, who got transported to the Cretaceous, couldn't answer that question. Sam he knew humans would one day evolve and he actually attempted to establish one-way communication with them (and unknowingly succeeded).

Simpson, in fact, started his story by introducing the dilemma of absolute loneliness:

"What would you do," asked the Universal Historian, "what could you do if you knew you were going to be utterly alone for the rest of your life?"

"That's something, we'll never find out," said the Pragmatist. "The situation could not arise."
What would I do if I found myself alone on a quiet earth one morning? There would be enough dry and canned foods available (freely) to sustain one person for a long time. So, obtaining food wouldn't be a concern. I think I would just start traveling. One challenge would be to cross over to Asia. I couldn't fly a plane and walking across the frozen Arctic Sea over to Asia would be too difficult. But I could probably handle a small boat. So, I would probably attempt to sail over to Asia from Alaska.

But would I feel lonely?

*A man and a woman. Predictably, a love triangle develops and the movie loses its originality. But that's off the subject.

13 June 2008

Order your thing now!

Snail's Tales' Department of Totally Useless Information would like you to know that according to a Google search conducted today around 1900 hours, there were on the Internet about 41, 700,000 items for sale for $99.

Send me a check for $99 or cash (sorry, no credit cards) with your address and I will send you something in return. I promise.

Is there a "zone of maladaptedness" between the sea and the land?

In an essay titled Does microevolution explain macroevolution?, Ernst Mayr, wrote:

What is so often forgotten in the discussion of evolutionary discontinuities is that they represent not only a structural discontinuity but also an ecological one. A new niche and, particularly, a new adaptive zone is often separated from the ancestral one by a pronounced gap. There is no well-adapted condition for the area between the two adaptive zones. Hence, when a new adaptive zone is first invaded, a zone of maladaptedness has to be crossed.
Ever since I read this passage about 2 months ago, I've been trying to understand what exactly Mayr meant by "zone of maladaptedness". I think he implied one of the following mutually exclusive meanings:

(1) There is a permanent transition zone between the ancestral and descendant zones where no species is ever well adapted.

(2) Initially, no ancestral species is well adapted to the transition zone and only after they have evolved preadapations to life in the transition zone, can they enter it.

The problem is Mayr's 2nd from the last sentence seems to support the 1st meaning, while his last sentence seems to support the 2nd meaning.

Furthermore, in the next paragraph, Mayr wrote:
No organism can invade a new adaptive zone unless it has a minimum of structural, physiological, and behavioral attributes that preadapt it to succeed in this shift.
This statement also supports the 2nd meaning.

My interest is in the transition zone between the sea and the land. Specifically, I am trying to understand how ancestral marine gastropods evolved to become terrestrial. If Mayr meant that coastal habitats are zones of maladaptedness where no gastropod species is well adapted to live, then I totally disagree with him. The semi-terrestrial gastropods of coastal habitats are as well adapted to their habitats as all other gastropod species are to their specific habitats.

But if, on the other hand, Mayr meant that ancestral marine gastropods needed to evolve preadapations before their descendants started to move into the coastal habitats, then, yes, he was correct.

Some gastropods of the transition zone between the sea and the land that were featured on this blog: Assiminea succinea, Cerithidea scalariformis, Melampus bullaoides, Littoraria angulifera.

*Towards a New Philosophy of Biology. Harvard U. Press, 1988.

12 June 2008

Baby Assiminea succinea

The live Assiminea succinea I brought back from Florida at the end of March are doing well and, in fact, have been making baby snails in their own images (but see below).


This undoubtedly newly hatched snail, just about 0.4 mm wide and 0.26 mm high, was near the limit of magnification of my camera. Being wider than they are high, the babies are actually not quite the images of their parents, which have tall shells. Soon, the body whorl of the baby snail must take a downward turn and start growing a more elongated shell.

The previous posts on A. succinea were here and here.

11 June 2008

A straight plug for a gay musician

Regular readers of this blog must have figured out by now that I am not gay and I don't write about such subjects (not that there is anything wrong with it). But today I will make an exception and insert this post for my friend Don Harvey, who happens to be gay and a musician.

Don recently released Good Clean Fun, his 1st CD. The CD features 16 songs Don wrote and sang, whilst playing the bass, acoustic and electric guitars and an organ of some sort.


A few months ago when Don mentioned that he was working on a CD, he warned me that it was gay music. My response was something like "Music is music, how can there be gay music?" Don’s explanation was simple: "The lyrics are about gays." Of course, the lyrics!
We’re sailing on to Constantinople
And our life on our ship is just grand
Out here on the ocean we’ve nothing to fear
We wash down our suppers with tall steins of beer
And we choose for a bunkmate a man to hold near
We’d fight for our country for free
Just give us a life on the sea!

We’re sailing into Constantinople
Our brave Captain warned us it’s true:
That when we’re ashore we’ll be put through our paces
By big Turkish studs wearing black boots with laces
Our heels in the air and broad smiles on our faces
As happy as sailors can be
The Navy’s the lifestyle for me!

Sailing to Constantinople by Don Harvey (written for an old photograph of beer drinking German sailors and in remembrance of William Butler Yeats' poem Sailing to Byzantium)
Don's a pretty good guitar player. But I don't quite know how to describe his music. Pop? Rock? Mostly acoustic pop-rock? There are even some shades of country, folk and blues. Some of the harmonies actually reminded me of the Moody Blues. My wife read the lyrics (to make sure I wasn't getting too out of hand) and declared that for the most part, they were clever and funny.

"And if you hear some thumpin', it's just Jake pumping DNA in his buddy's back door."

Good Clean Fun is available here (where you can also listen to a 2-minute sample of each song).

My favorite Don Harvey tune What would you say? could, with a little bit of wild imagination, easily pass for a straight song.
What if I asked you to come take a walk with me
Down to the river to swim in the nude?
Would you unravel and become unglued by it?
What if I asked you if this makes you think that I'm rude?

What would you say?

What if I told you that we've drawn a bath for you?
Six grinning soldiers say "Take off your clothes!"
Climb in the tub and twelve hands will take care of you
Lather you up from your head to the tips of your toes!

What would you say?

Don is also an accomplished lepidopterist at a major research institution. Recently, he got interested in gastropods with long penises (and that's how our paths crossed). He and I will be having good, clean slimy malacological fun for many years to come.

10 June 2008

A friend went to Bar Harbor and all I got was Littorina littorea

Scale is in millimeters.

When Judy and her husband Bob returned from their vacation in Bar Harbor, Maine in September 2007, they brought back for me a couple of snails preserved in alcohol. Only recently did I have a chance to examine and identify the snails as Littorina littorea, a gastropod of the rocky intertidal.

This provided the impetus to read about an ongoing controversy in American malacology centered upon this species: is L. littorea native to the northeast coasts of North America or was it introduced by humans from Europe?

Live L. littorea was first found in North America in 1840 on the shore of the Gulf of St. Lawrence in Canada. By 1890, the snail had arrived at New Jersey coast about 1,300 km to the south. The rapid expansion of its range is usually considered to be a strong indication that it was brought intentionally from Europe as food (they are edible) by 19th century European settlers or even much earlier by the Vikings.

Widening of the range of L. littorea along the coast of northeast America. Map from Bertness, M.D. 2007. Atlantic Shorelines, Princeton U. Press; original from Carlton, J.T. 1982. Malacological Review, 15:146.

Recent papers arguing for the nativeness of L. littorea is Cunningham (2008) and for its exoticness are Chapman et al. (2007; 2008).

The main argument of Chapman et al. (2007), in summary, is the following:
No available genetic evidence demonstrates that North American L. littorea were isolated from Europe for millennia. The low allozyme and haplotype diversity of North American L. littorea is characteristic of a recent (past 200–1,000 years) introduction...
Whereas Cunningham (2008) claims that
Taken as a whole, the DNA sequence data supports the many sub-fossil reports of an American L. littorea population in the Canadian maritimes that preceded even the first visits by the Vikings.
The most definitive answer will perhaps be provided if fossil shells predating the Viking visits are ever located somewhere in Canada or the northest U.S.

John W. Chapman, James T. Carlton, M. Renee Bellinger & April M. H. Blakeslee. (2008). Premature refutation of a human-mediated marine species introduction: the case history of the marine snail Littorina littorea in the northwestern Atlantic. Biological Invasions 9:737-750. [Curiously, another copy of this paper with a different abstract was also published in Biological Invasions 9:995-1008.]

John W. Chapman, James T. Carlton, M. Renee Bellinger & April M. H. Blakeslee. (2008). Parsimony dictates a human introduction: on the use of genetic and other data to distinguish between the natural and human-mediated invasion of the European snail
Littorina littorea in North America. Biological Invasions 10:131-133.

Cunningham, C.W. (2008). How to Use Genetic Data to Distinguish Between Natural and Human-Mediated Introduction of
Littorina littorea to North America. Biological Invasions 10:1-6. pdf

09 June 2008

Arboreal isopods

Tree climbing isopods were featured on this blog before in this post.

Last Saturday night after a thunderstorm, I found 2 species of isopods on the trunk of a young apple tree in the backyard. One of them was Philoscia muscorum*.


And the other one was Armadillidium nasatum. Here are representatives of both species together after I brought them indoors for a closer look. Philoscia is on the left, Armadillidium is on the right.


Why do isopods climb trees? Probably they feed on the fungi that grow on tree trunks.

*My isopod identifications are always tentative, pending confirmation. So I could be wrong.

08 June 2008

Grandfather at ease


This was my mother's father, Tevfik (later Tevfik Çelebican) possibly during the First World War when he served in the Ottoman Army. After the war, he got married, had 4 children, 3 of whom grew to be adults, operated a grocery store in a small town and drove his own car. The latter must have been a rare sight in rural Turkey during the period between the 2 world wars. Although Turkey did not enter the Second World War, Tevfik was drafted again. Unfortunately, he got sick and died at a military hospital in 1942 at the young age of 46. Therefore, in 1918, when the First World War ended, he would have been about 22. He indeed appears to have been in his early twenties in the picture.

Now, let's take a closer look at his photograph. That Tevfik was carrying a sword possibly means he was a low-ranking officer, despite his young age. His belt buckle displays the Ottoman-Turkish upturned crescent and the star above it. The object hanging next to his scabbard attracted my attention (red arrow), but I had no idea what it was until my friend Richard Greene, a military uniform buff, identified it as a sword knot.


Moving further down, we come to the footgear. Again thanks to Richard's expertise, Tevfik's leg coverings were identified as leather puttees.


I don't know what to make of the stains on his pants. My sister, who has the photograph, claims that it is the picture itself that is stained. Let's hope Tevfik wasn't posing in bloody pants after a victorious battle.

Incidentally, the sword visible in the picture, or something similar to that, is still in the family's possession.

Revision added several hours later: Soon after I posted these pictures, my cousin Mete in Turkey, a grandson of Tevfik, e-mailed me a scan of a better preserved copy of the same picture (although this one has a deep crease across it). It turns out that Tevfik's pants were not bloody after all! This copy also has the date of [1]337 (in the Islamic Hicri/Hijri calendar), written on the bottom and which corresponds to 1918/1919 (it is not possible to determine the exact year without knowing the month). So my estimation of Tevfik's age in the picture was correct.


07 June 2008

A tropical contortionist: Opeas pyrgula

Opeas pyrgula in the field. Left: 2 empty shells and 1 live adult (middle); Right: Juvenile.

Opeas pyrgula is considered to be originally a "tropical and subtropical" land snail species (Pilsbry, Land Mollusca of North America, 1946), but as a result of human activities, the species has long been distributed to many other parts of the world.

In Maryland, they are closely associated with railroads and may be found, sometimes in large numbers, under pieces of wood, large rocks or other types of semi-permanent material that provide a damp environment and offer protection from the weather. I suspect some railroad activity is responsible for their distribution, but I don't know what that may be.

I took the picture above in the field. The snails were on damp soil under a large chunk of concrete. On several occasions last winter at the same spot, I had found only empty shells; the live snails were present a few days ago. One wouldn't think that even a subtropical snail species would survive the winters this far up north, but they apparently do. It is unlikely that they are reintroduced every spring. I think O. pyrgula avoids the freezing surface temperatures by burying deep into the soil.

NatureServe lists records from several mostly eastern and southern U.S. states. There is even an unconfirmed record from Canada.

Like its close relative Subulina octona, another introduced species, O. pyrgula can also contort its body and shell into, what appear to my human eyes, awkward positions. The snail in the picture below was turning around on a horizontal surface.


More pictures of O. pyrgula are available at the Jacksonville Shell Club.

06 June 2008

I was starting to feel powerless

Sometime after midnight last night my neighborhood lost electricity. Around 9 o'clock this morning about a dozen trucks and about 2 dozen men wearing thick, yellow rubber boots appeared and started working. A manhole housing several high voltage cables on our front yard quickly became one of the focal points of their activities.


The men wearing thick, yellow rubber boots worked all day. Finally, around 8:40 this evening just as it was starting to get dark in the house, we were endowed with power again.

What would we do without electricity?

05 June 2008

Off with Lavoisier's head, get on with chemistry

Antoine-Laurent Lavoisier (1743-1794) was one of the founders of the modern science of chemistry. His experimental findings towards the end of the 18th century were instrumental in the demolition of the ill-defined, nebulous phlogiston theory that had all but stifled the progress of physical sciences during most of that century. The multitasker Lavoisier also held several influential government positions. Apparently mostly because of his involment in tax collection, and despite his scientific fame, he eventually lost his head to the guillotine during the turbulent aftermath of the French Revolution.

I just finished reading Madison Smartt Bell’s Lavoisier in the Year One (W.W. Norton, 2005), a biography of the original chemist. I didn't quite like the book for several reasons. First, I am not sure how much of the book is original material that was derived from original sources. For one thing, the Notes section at the end gives me the impression that most, if not all, of the quotations in the book are regurgitations of what was already in Lavoisier’s previous biographies. Gathering up all the existing biographies of a person and then writing a "new" biography out of them doesn’t sound like a big deal to me.

Second, I found the author’s habit of mixing up the chronological orders of events quite confusing and annoying. Example: the very 1st sentence of the book is about the events of 1793, the year before Lavoisier died; as the chapter progresses, the narrative moves backward; rather annoying. Another example: chapter V begins in August 1789, but on the next page we suddenly return to March 1789 and start over again; rather confusing.

Third, Mr. Bell’s apparent lack of a background in chemistry seems to have introduced a few errors that an editorial review should have corrected. Example: The footnote on page 94 states that “Carbon dioxide dissolved in limewater {Ca(OH)2(aq)} precipitates carbonate ion {CaCO3}.” What precipitates is not carbonate ion, but calcium carbonate proper, CaCO3. Also, I had never seen the use of curly brackets ({}) around chemical formulae before.

Criticism aside, I did learn from this book, but that was mostly because I knew very little about Lavoisier’s life before. On a scale of 1 to 5, I’d give Lavoisier in the Year One a 2.

I have also posted a shorter version of this review at Amazon.

The famous painting of Lavoisier and his cheatin’ wife Marie-Anne was the subject of this post.

04 June 2008

Still red after all these months

During an after lunch walk near the end of last January, I found and marked (with red ink) 8 live, but dormant, adults of a land snail, a Triodopsis species. These snails were at the same spot where I had collected roughly 300 empty shells of them several months earlier.

I returned at the end of February and marked, again with red ink, all the adults (25) I could find. On 17 April, I found 12 of those snails and remarked them with red ink. At the same time, I saw 9 unmarked adults, which I marked with green ink.

Yesterday, I went back. Expectedly, the place had changed quite a bit since April. There were now plants growing everywhere and one of the small boards under which some of the snails were taking refuge had been displaced. Back in April, I noticed that since the end of winter the snails had gotten more mobile and some had left their winter homes. Their increased mobility, of course, makes it more difficult to locate them.

Yesterday, the plant cover also made it difficult to search for snails, but I could still find 10 adults. None was marked green, but one was carrying its red line behind its lip.


Now I know for sure that the adults of this species survive the winter and some live at least until June. One day next week I will go back and carry out a more thorough search. I will also mark all the unmarked snails I can find with a yet different color.

03 June 2008

Ride my seesaw

Google Analytics has a relatively new feature called benchmarking that lets you compare your site’s visitor statistics anonymously with average statistics (benchmark data) for other sites of similar size. This helps to determine if the visits to your site are in line with the general trends.

I have done this for Snail’s Tales for 1 March 2008 thru 31 May 2008.

The thick blue line is the number of visits to Snail’s Tales , the gray line is the benchmark data.

The characteristic sawtooth pattern of the weekly fluctuations in the number of visitors is obvious both for Snail’s Tales and for the benchmark data. The visitor numbers seem to peak during Monday thru Wednesday and then dip during the weekend.

The weekly fluctuations in the number of visitors was the also the subject of this post.

02 June 2008

A bug not a beetle: Poecilocapsus lineatus


I photographed this insect (~6-7 mm long) in my backyard late yesterday afternoon. Later I posted its picture on BugGuide.net and called it a "red-headed beetle?". Less than 40 minutes later it got identified as Poecilocapsus lineatus, the four-lined plant bug. As its name implied, it was not a beetle (order Coleoptera), but a bug (order Hemiptera) in the family Miridae.

My confusion was due to its unfamiliar wing morphology. I had assumed the yellow and black part was the wing cover (the elytron of a beetle) and the membranous part, which I thought was sticking out from underneath, was the hind wing. It turned out that the entire thing was the wing itself. The figure below explains it.

The wing of a mirid bug. From Gullan & Cranston, The Insects, 3rd ed., 2005.

According to Swan & Papp (The Common Insets of North America, 1972), these bugs feed on the leaves of several plants, including phlox. We do have several phlox plants in the backyard, although when I saw this individual, it wasn't on one of them.

01 June 2008

Melongena corona at low tide

The crown conch (Melongena corona) is a common intertidal species along Florida coasts. According to Malacolog, the habitat of this species goes down to depth of only about a meter or so.

So, what does Melongena corona do when the tide is out? It buries itself in the wet sand until only the top of its shell is left exposed to the air. Here is one I photographed at low tide near Tampa, Florida last March.


To make sure it wasn't just an empty shell, I pulled it out of the sand and turned it over. The operculum and parts of the snail's foot are visible within the aperture.


Ilyanassa obsoleta, another intertidal snail along the eastern shores of North America, survives the low tide also by burying itself in the sand as illustrated in this post.

Two previous posts were about Melongena's siphon and the snail's behavior outside the sea.