Bipalium adventitium — Part 5

I have been keeping a land planarian, Bipalium adventitium, since about the end of September. In part 3 and part 4 of this series, I chronicled my attempts to feed slugs to it. In fact, I now have enough data for a short paper that I am co-authoring with Megan P.

According to several published studies (citations below), the preferred, and perhaps the sole, prey of this planarian are earthworms. Bipalium adventitium is a passive-aggressive predator. It doesn't seem to chase after its prey, but attack one only if it happens to bump into one while foraging.

Several studies have also described the predatory behavior of B. adventitium (citations below). When a hungry planarian makes contact with an earthworm, it climbs on the worm and everts its pharynx. The earthworm is quickly immobilized apparently by the planarian’s pharynx. The planarian then starts to consume the worm. Here is a photo showing the planarian eating a worm. Note that the planarian's mouth is not in or anywhere near its head; it's on the ventral side near the middle of the body.

The light colored tissue covering a portion of the earthworm’s body is the planarian’s everted pharynx (arrow).
During this process the worm continues to move its head or tail for up to 45 minutes, but is otherwise incapable of freeing itself from the planarian.

And here is a short film* of an earthworm being devoured alive by B. adventitium. The planarian, light brown, is on top of the darker colored worm. You can see one end of the worm moving. During the 2nd half of the clip, the planarian's head is also visible.


I don't know if earthworms can feel pain; if they do, this must be a horrendous way to die. But, as Richard Dawkins said in his book River out of Eden, "nature is not cruel, only pitilessly indifferent" to such petty affairs. Planarians must eat too.

Part 6 is here.


*Once again, I apologize for the poor quality of the movie. This is the best I can do with my present camera.

Dindal, D.L. 1970. Feeding behavior of a terrestrial turbellarian, Bipalium adventitium. American Midland Naturalist 83:635-637.

Ducey, P.K. & Noce, S. 1998. Successful invasion of New York state by the terrestrial planarian, Bipalium adventitium. Northeastern Naturalist 5:199-206.

Ducey, P.K., Messere, M., Lapoint, K. & Noce, S. 1999. Lumbricid prey and potential herpetofaunal predators of the invading terrestrial flatworm Bipalium adventitium (Turbellaria: Tricladida: Terricola). American Midland Naturalist 141: 305-314.

Ducey, P.K., McCormick, M. & Davidson, E. 2007. Natural history observations on Bipalium cf. vagum Jones and Sterrer (Platyhelminthes: Tricladida), a terrestrial broadhead planarian new to North America. Southeastern Naturalist 6: 449–460.

Fiore, C., Tull, J.L., Zehner, S. & Ducey, P.K. 2004. Tracking and predation on earthworms by the invasive terrestrial planarian Bipalium adventitium (Tricladida, Platyhelminthes). Behavioural Processes 67: 327-334.

Zaborski, E.R. 2002. Observations on feeding behavior by the terrestrial flatworm Bipalium adventitium (Platyhelminthes: Tricladida: Terricola) from Illinois. American Midland Naturalist 148: 401-408.

A lichen with legs

These small, mobile bits of lichen with formidable pinchers are quite common on the trees in the park near my house. They are apparently lacewing larvae, usually about 6-9 mm long, that have covered themselves bits of lichen.

If you pick one up, first, it curls up turning into a little ball of lichen. Then slowly, the ball begins to unroll briefly displaying the larva's belly and legs. Here is one upside down on the palm of my hand.


Finally, it executes a backward somersault and gets back on its legs.


I was seeing them back in July and I saw them again last weekend. Obviously, some of them survive the winter as larvae to mature in the spring.

It is said that the lichen camouflage offers protection against predators. Perhaps. I don't know how a larva attaches the lichen bits on its back. It would be interesting to watch one cover itself.

It came out of a snail shell

But it's not a snail. It's an isopod, specifically, a Philoscia muscorum*. Here it is before it was forcefully evicted from its abode, a shell of Cepaea nemoralis that was devoid of a snail.


Of the about 130 Cepaea shells I collected last weekend, 3 had isopods in them. Empty land snail shells are prime real estate for many invertebrates that are small enough to fit in them. I took that sentence verbatim from this post where the occupant of the shell was a thrips.

I am thinking of putting some empty snail shells in my yard to see if any isopods will move in.

*Thanks to Joan and Barbara for conforming the ID.

Not exactly geocaching

While rummaging in the woods for snails and slugs earlier today, I came upon a well hidden geocache box. What are the chances of finding one of these when you are not actually looking for one?

I opened it hoping to plunder the contents, but there were only a log book and assorted junk, including a golf ball and a small plastic doll. I am not sure what the rules of this game are. Are you supposed leave something in the box? I didn't leave anything or take anything; the 2 snail shells I had found earlier were too good to part with.

I did enter the URL for this blog in the log book, though.

One more 19th century painting of a terrestrial gastropod and a malacologist's story

This picture of the snail formerly known as Helix aspersa adorns the cover of M. S. Lovell's 1867 book The edible mollusks of Great Britain and Ireland with recipes for cooking them. The book is available at the Biodiversity Heritage Library. I have scrolled thru the book quickly and noticed, in addition to recipes, many records, natural history observations and other miscellanea related to edible mollusks and also 12 colored plates.

The following anecdote is from page 20 and was taken from the famous 19th century malacologist E. A. Rossmässler's Reise-Erinnerungen aus Spanien.

Much amusement was afforded to the Spaniards, by Rossmässler throwing away the delicate animal, and only retaining its shell, which to them was worthless, but most valuable to him as a conchologist. Upon one occasion, on arriving at a posada, he found the hotel people sitting down to their midday meal, before a great dish full of snails. He says:—"One look satisfied me that they were of a rare kind, for which I had sought in vain; and I immediately seized upon some of the empty shells, which caused a universal laugh.

To a modern malacologist the snails' bodies would be as valuable as their shells. Rossmässler would undoubtedly have done the future malacologists a great favor if he had saved a snail or two along with their shells.

The previous 19th century painting of terrestrial gastropods was here.

The Aqueduct of Vallonia

This is the Alexandria Aqueduct, or what is left of it, in Georgetown, Washington, D.C. According to Mike High's The C&O Canal Companion (1997), the aqueduct once connected the C&O Canal to another canal (not named in the book) on the Virginia side across the Potomac River, which is visible on the right (the Key Bridge is in the background). The C&O Canal is towards the left of the aqueduct in this picture.

I was there last Friday. I noticed that parts of the walls of the aqueduct were wet from water seeping out from between the rock blocks (it had rained the day before). A close inspection revealed tiny snails crawling on a section of the wet wall partially covered with red ivies (towards the lower left in the photo). A closer inspection revealed that the tiny snails were Vallonia.


They are either Vallonia pulchella or V. excentrica, the 2 being somewhat hard to distinguish. Their shell diameter is ~2.3 mm.

The next time I am there I will check again to see if the snails are always out on the wall.

Bipalium adventitium — Part 4

In part 3 of this series, I attempted to feed a slug, Megapallifera mutabilis, to my "pet" planarian Bipalium adventitium. The planarian refused. In the comments, Megan P. suggested that I repeat the experiment with baby slugs. You see, as long as it is in the name of science, we can even feed babies to predators. We are collecting data here.

I thought Megan's idea was worth a try, but I was freshly out of baby slugs. Luckily, Megan had some and was willing to part with a few. So, last Thursday I visited her lab at the University of MD and returned home with 3 juvenile Philomycus carolinianus, another native species in our favorite slug family the Philomycidae. And early this evening, I offered them to El Depredador that had been waiting patiently in the basement.

So far the slugs have survived. But the night is young and there is plenty of time for a surprise pharynx eversion.

To be continued.

Fluid trends

In the previous post in this series, the index of satisfaction (IS = optimism / happiness) had stabilized for a change. However, the most recent data clearly demonstrate that the long term trends are fraught with uncertainty.

A sharp drop followed by a gradual recovery was nobody's guess. And once again, we don't know if it's optimism that's going thru a turbulent period or happiness is fluctuating depending on the amount of wine intake.

I will continue to monitor this crucial index and provide updates.

How about a long penis covered with spikes?

The arrow is pointing at the pointed papillae covering the penis of Chondrus tournefortianus. I don't know what function the papillae may have.
The picture shows the everted penis of the land snail Chondrus tournefortianus. This hapless pair was mating on a hillside at the outskirts of the city of Kastamonu, Turkey one cold and wet morning in October 2008 when I chanced upon them. Not only did I intrude upon their privacy by photographing them, but I also pulled them apart to see if their mating was anatomically reciprocal.

Remember that pulmonate snails, and that is what these are, carry both male and female; in other words, they are hermaphrodites. Therefore, when they mate, it is possible for each snail in a pair to use its penis to inseminate its partner. In many snail species, mating is indeed anatomically reciprocal*. But in some species only one snail acts as the male and gets to inseminate its partner.

One way to determine if the mating of a pair is anatomically reciprocal is to kill them in copula and then to dissect them. I don’t particularly like killing snails, especially if they are in the process of performing a fundamental evolutionary act, that is, passing on their genes. So instead, I pull them apart while watching them under a microscope or a magnifying glass, if I am in the field, and hoping to see their penises as they are being withdrawn (more about that technique here). Other than one interrupted coitus, no damage is done.

In the case of this particular pair of Chondrus tournefortianus, after I separated them, I saw the penis of only one snail and, therefore, concluded that their mating was anatomically unilateral. The details of this lucky encounter and how it has contributed to our knowledge (or the lack thereof) of the family Enidae, to which this species belongs, have just been published in a short paper of mine in the journal Zoology in the Middle East. You may read it here. The paper also has a photo of the mating snails before I took the matter into my hands.


*Strictly speaking, anatomical reciprocity doesn’t necessarily mean reciprocal insemination; an individual could mate without contributing sperm. Anatomical reciprocity can also be simultaneous or sequential. Yes, I know, it does get complicated.

Another 19th century painting of terrestrial gastropods

This is Tafel XI from an 1889 paper by E. von Martens*. The drawing of the live snail on the bottom represents a Helix asemnis venusta, a species of southwestern Turkey and the nearby Greek Islands.


The previous 19th century painting of terrestrial gastropods was here.


*E. von Martens. 1889. Griechische Mollusken. Archiv für Naturgeschichte 55:169. (Full text from the Biodiversity Heritage Library.)

A true confession: I was Otto Mann

The magazine American Rationalist praises itself for being an "Alternative to Superstition and Nonsense" for over 50 years. I subscribed to it for several years in the 1990s. Then I got tired of it, although I don't quite remember why, and ended my subscription.

However, I did publish one article in the AR. It came out in the November-December 1993 issue. It was titled Life, Death and Mind Transfer and was about, well, life, death and mind transfer.

Recently, I read again what I had written and quite liked it. Although, I admit, there isn't much in it that was original—at least it seems that way to me now, almost 17 years later. Mind transfer has been a favorite subject of many a science fiction story.

Nevertheless, I decided to scan it and upload it to my library for all to read. Here it is.

The funny thing about this article is that I published it under the pseudonym Otto Mann, although, again, I don't quite remember why. If anyone doubts that I was Otto Mann, I do have a short note to that effect from the late Gordon Stein, the then editor of AR. I also cite one of my own papers for whatever it may be worth.

A few years later I published another article somewhere else as Otto Mann. I will put that up some other time.

Bootleg proceedings of the 3rd OVUM meeting

The 3rd annual meeting of the Ohio (River) Valley Unified Malacologists (OVUM), organized by Tim Pearce, took place at the Carnegie Museum of Natural History in Pittsburgh yesterday. There were 14 participants and 11 presentations. Here are the speakers and very brief summaries of what I thought they talked about in the order of presentation.

Charlie Sturm (CMNH): Ongoing attempts to locate the field notes that were associated with the freshwater mollusk collection of Herman P. Wright that was donated to the Carnegie Museum in 1932 and which has since been sitting uncatalogued in a drawer.

Tim Pearce (CMNH): Studies to correlate the weather data with the short-term movements of snails.

Francisco Borrero (Cincinnati Museum of Natural History): taphonomic evidence for turnover in the freshwater mussel community in the Ohio Brush Creek.

Aydin Örstan (CMNH): Results of the survey done to determine the present range of Cepaea nemoralis in Frederick County, MD that was introduced by the late Wayne Grimm in 1969.

Andrew Turner (Clarion University): Elevated pH, caused by nutrient enrichment (increased phosphorus levels), may interfere with the freshwater gastropods' detection of the chemical cues produced by their predators.

Beth Meyer (Western Pennsylvania Conservancy): Mussel, fish and macroinverterbate survey of the French Creek, PA.

Nevin Welte (WPC): Recent PA Fish and Boat Commission activities related to mussels. These included the collection and relocation of a large number of mussels from behind Carter’s Dam prior to its removal.

Emily Cholak (Clarion University): Effect of predation risk induced by fish and crayfish on the population dynamics of their prey, the freshwater gastropod Helisoma trivolvis.

Kip Brady (New Philadelphia High School): Ecological projects involving freshwater gastropods in high school biology classes. Will the students develop a better appreciation of wildlife?

Tim Pearce (CMNH): Laboratory experiments to determine if the slug Philomycus carolinianus likes to aggregate with its conspecifics?

Aaron Stoler (University of Pittsburgh): How the presence of leaves from different species of trees in the water affect the survival of tadpoles and the gastropods Physa acuta and Helisoma trivolvis.

T. rex was there too.

Not necessarily profound questions from my notebooks – Part 1

—The results of one set of data may be interpreted in conflicting ways to produce more than one truth statement. How can a minimalist research program avoid this difficulty?

—Once while walking, I encountered 5 Canada geese. Two of them started honking and flew away, but the other 3 simply walked out of my way. Will we ever be able to understand what factors create such behavioral differences at a given moment?

—Do the internal vestigial shells of slugs have a function?

—How small is the smallest piece of cytoplasm that can be considered alive?

—Is there a dimensional threshold below which a brain cannot develop consciousness or is consciousness present all the way down to the smallest animals with brains?

Grey heron in the C&O Canal.
To be continued.

Absence of evidence could be evidence of absence

You don't see an elephant in this picture, do you? I don't see one either. In fact, when I was there I looked around carefully, but did not see any elephants. Besides, this picture was taken in Maryland where no wild elephant has ever been recorded. And when I took this picture, there was no nearby circus or zoo reporting a missing elephant.

Therefore, I conclude that my observations and this photograph prove that there was no elephant at that point at that time.

I just proved a negative.

OVUM Meeting will be this Saturday

The 3rd annual meeting of OVUM, the Ohio (River) Valley Unified Malacologists, will be held on Saturday 14 November 2009 at the Carnegie Museum of Natural History, 4400 Forbes Ave., Pittsburgh, PA.

From the e-mail announcement:

This one-day meeting will run from (9:30) 10 am until the last presentation (to end by 5 pm at the latest). Light refreshments such as fruit, bagels, coffee, tea, and water will be available from 9:30-10:00 am. The meeting will be held in Multipurpose Classroom B. Participants should sign in at the Security Office at the Portal Entrance (off the Parking Lot), then follow signs a short distance to the meeting room.

The meeting is open to professionals, amateurs, and students; basically anyone who has an interest in mollusks. OVUM has no dues, officers, abstracts, or publications. Even busy people can spend a day networking and talking about mollusks.

Please limit presentations to 15 minutes.

For more information contact Tim Pearce (PearceT AT CarnegieMNH.org).

I am planning to go, barring last minute changes to my plans.

Flattened fauna of sidewalks - Part 5

Part 4 of this series came out in December of last year, almost a year ago. I follow the better late than never principle and continue along.

The first victim of this installment is a spider of some sort. It was more shriveled up than flattened.

Next, we have a squished mantis on a parking lot. It was definitely a case of hit and park. Despite all that incessant praying, the mantis had a grisly death. As they say, nothing fails like a prayer. Ha, ha, ha!


And here is a first for this series: a flattened mammal, a shrew probably. It comes with an assortment of corpse-licking flies. Enjoy!



To be continued...

Garter snake in C&O Canal

Last Friday, I was watching a couple of mallards swimming in the C&O Canal near Georgetown. Suddenly, a long, skinny object appeared in the water and started undulating rapidly towards the bank. I gazed at it in amazement for a few seconds before my brain circuitry announced that it was a snake. By the time I finished fumbling with my bag and managed to take my camera out, it had left the water and disappeared. Then I spotted it among the mud covered leaves climbing up the bank (I turned the picture sideways to make it fit the page better). Two shots were all I could take before it disappeared again, this time below the cliff I was standing on.

This is a garter snake (Thamnophis sirtalis). In the original post I had identified it as a ribbon snake (Thamnophis sauritus). However, one commenter indicated that it was instead a garter snake (see below). After I obtained confirmation from another source, I revised the post.

Rain drain on a windy day

Butterfly (and dandelion) in November

This is the best shot of this butterfly I saw yesterday. Today at the same spot, there were 2 of them frolicking, but they disappeared before I could approach them.

It is one of the sulphurs, either the clouded sulphur (Colias philodice) or the orange sulphur (C. eurytheme). I don't know how to tell them apart.

I don't want to know what muktuk tastes like

In this post back in April 2008 I asked myself the question of how a person who eats only meat can avoid getting scurvy, vitamin C deficiency.

Not too long ago, a New Scientist reader asked a similar question: how do traditional Inuit avoid scurvy? An answer has been given in this week's issue of the magazine. The Inuit apparently avoid succumbing to scurvy by eating something called muktuk. Muktuk consists of whale skin and blubber and is high in vitamin C. Eating enough of it would satisfy their vitamin C requirement.

The answer to my own question was that the yak hunter Aldat, the subject of my post, could have avoided scurvy by eating tongues and liver of yak.

As for me, I think I will go get a glass of orange juice.

A spider that had its nest on a sycamore leaf

One windy day about 10 days ago, the sycamore tree on our street lost many of its leaves. I happened to be passing by and picked up one of them. While examining the leaf, I noticed that one lobe was attached along a vein to another lobe by silky material. I pulled the lobes apart and out came a small spider.

Luckily the spider stayed on the leaf while I brought the leaf in and took a series of pictures. Subsequently, it even went back into its partially destroyed abode.


Obviously, this spider lives high up on the trees. But where does it go when the autumn comes and the leaves fall? Does it prefer sycamore trees, which have rather large leaves? After the photo session, I put the leaf behind some bushes in my yard. As of this afternoon, it was still there, but I didn't check to see if the spider was still on it. I'll do that in a few days.

I just posted the pictures on BugGuide.net. Maybe someone will identify the spider.

The view from inside the nostril

I don't claim to be an artist. But then again, what is art and what does one need to create to become an artist? I do have a few creations of my own. For what it's worth, here is one of the oldest surviving ones.

Blue ballpoint pen on cheap paper. 7x10 cm. Now slightly faded.
The detailed title explains what it is depicting: The outside scenic view as seen from inside the nose—thru the nostril—of a man. Those 2 scimitar-shaped things are nose hairs, while the irregular entity on the right is mucus. I used to wear my watch on my right wrist. Note that the right hand visible outside the nose is also wearing a watch. So, this is presumably a self-portrait of sorts.

It is dated 15 December 1976, midnight. Arguably, a piece of "art" like this can only be created late at night, preferably after midnight when the time is usually ripe for finding out what it is all about.

If Salvador Dalí had doodled this, it would be worth a hefty sum now. But, sigh, I am no Dalí...

Bipalium adventitium — Part 3

Bipalium adventitium is a predatory terrestrial planarian. Klots (1960) reported that B. adventitium preyed on "small annelids" as well as on slugs and insect larvae. He did not, however, give details or specify what species of slugs the planarians had eaten. According to recent studies, B. adventitium preys exclusively on earthworms. For example, Ducey & Noce (1998) reported that their specimens did not eat 2 species of slugs (Arion sp. and Deroceras sp.) that were offered to them.

I have had one captive B. adventitium since the end of September. I have fed it 2 earthworms and I have also been testing to see if it will eat the native northeast American slug, Megapallifera mutabilis. In the first test I did 2 weeks ago, 2 slugs survived about 20 h in the same container with the planarian. On several occasions, I observed the planarian contacting the slugs and also crawling on them, but it never, as far as I could tell, attempted to attack them by everting its pharynx (yes, that's what they do).

Touch but don't eat: Bipalium adventitium making contact with a Megapallifera mutabilis.
Tonight's test started 3 hours ago. The planarian hasn't eaten in 20 days. As of 10 minutes ago, the slug was still alive.

The experiment continues in Part 4.


Ducey, P.K. & Noce, S. 1998. Successful invasion of New York state by the terrestrial flatworm, Bipalium adventitium. Northeastern Naturalist 5:199-206.
Klots, A.B. 1960. A terrestrial flatworm well established outdoors in the northeastern United States. Systematic Zoology 9:33-34.