31 October 2005

It's...


Welcome to the Greatest Show on the Internet. It's all about invertebrates, the rulers of this planet, our distant cousins. We've got the best spineless freaks, monsters, mutants, missing links, evolutionary dead ends and even a bearded lady, though she definitely has a spine.

There is plenty of time before the show starts. In the meantime, we would like to invite you to...


We have fabulous appetizers, sensational meals and scrumpdiddleumptious desserts. Please seat yourself and start looking at our menu. Your server will be with you in a minute. Bon appétit!

Appetizers

Arthropod sampler plate... $3.95

Box Elder Bug on passion vine leaves ... $3.25

Pickled snails ... $2.95

Woolly Bear caterpillars with extra fuzz ... $2.95


"Hi, my name is Sidonia. I will be your server."

Soups & Salads

White crownbeard salad with Swallowtails ... $4.25

Creosote bush salad with katydids ... $4.95

Sexless rotifer soup ... $5.95

Golden Orb Weaver sandwich ... $5.95

Mother and children reunion ... $4.50


Entrees

Sea spider heads with arthropod segments ... $11.95

Mixed snails in the shell, over a pile of dirt ... $12.95

Sawfly larvae in pungent sauce ... $11.95

Butterflies à la king ... $12.25


Desserts

Frozen Woolly Bear caterpillar ... $4.95

Ladyfingers with Hologram Moth topping ... $5.50

Pomegranate stuffed with paper wasps ... $5.50

Gulf Fritillary pudding with chrysanthemum ... $3.95

Spider jello flavored with staghorn sumac ... $3.50


How was everything? Please tip your server generously; she needs to buy lots of shavers.

Thanks to all the contributors. The 3rd performance of the Circus of the Spineless will be at the end of November at Urban Dragon Hunters.

A final note: My policy on this blog is not to have any links in any of my posts to any creationist (including "intelligent" design) sites. Hence I turned down a submission from one such site. I offer no apologies.

A final final note (Tuesday evening): OK, folks, we are not taking anymore comments on this post. It's time to move on.

30 October 2005

Halloween beer review: Dead Guy Ale


This is a bloody good ale with a cloudy orange-brown color and a nice mild flavor. It went well with aged gruyere cheese and honey roasted pecans. (Yes, I do like to eat unusual combinations of foods. Didn't I mention that before?) Next time you are dying for a good beer, you may want to give Dead Guy Ale a try.

But remember to drink in moderation, for too many of these will turn you into a zombie.

Cheers!

The previous beer review was K.

28 October 2005

A mixed-up meme

A while ago tony at milkriverblog tagged me with a meme, a fiver, and a few days ago afarensis tagged me with another one, also a fiver. So I decided to mix the two and answer only those I feel like answering. Here they are.

5 creatures I'd like to see before I go. [This one is from milkriverblog]

Metafruticola oerstani. My namesake for crying out loud. And I have only seen pictures of it.

Trichoplax adhaerens. The simplest of all animals and one of the only 2 members of the phylum Placozoa. It is a multicellular microscopic creature that lives in the sea.

Anatolian Leopard (Panthera pardus tulliana). Once common on the mountains of Anatolia, these big cats are probably extinct now, but then again a few may still be lingering.

A gorilla in the jungle (I have seen them in zoos, but that doesn't count).

Dodo! The legend has it that a man cannot die before he sees the beast he is dying to see. That means I will be immortal.

A great song I wouldn't mind never hearing again. [This one is from afarensis]

I happen to be listening to Dylan's Blonde on Blonde as I am writing these. So I will put down Sad Eyed Lady of the Lowlands.

Five movies that are my life. [From milkriverblog]

There isn't any. But I would like to have had a part—a small one—in Casablanca.

The book that took me the longest to finish. [From afarensis]
Darwin's On the Origin of Species. I have it on my bedside table and been reading it for about 2 years now and am not finishing it anytime soon. It's a fine book and I enjoy it, but there are so many other things to read that it always gets a low priority.

5 moments in my life that have changed everything I've done since. [From milkriverblog]

In my recent history there is only one such moment. It was on 11 August 1997 around 2 o'clock in the afternoon (details from my fieldbook). My cousin's family and I had been yachting along the southwestern coast of Turkey. We anchored at a small bay and I went ashore to look for suitable places where I could find bdelloid rotifers. Instead, on the side of a steep hill above the sea, I found 6 land snail shells in a hole under a rock. A few months later, I switched to studying snails. It was all because of those shells.

I am not tagging anyone. I'll let this meme die.

27 October 2005

The thing from the bird bath

bdelloid1

No, it's not a bird, it's a rotifer! Specifically, a bdelloid rotifer (possibly Philodina acuticornis).

This animal is a representative of a phylum of microscopic aquatic invertebrates known as the Rotifera. The identifying characteristic of them is the corona, the two ciliated disks surrounding their mouths. Despite being tiny―this particular individual was about 0.4 mm long―they have an almost complete set of organs, including a pair of jaws (the trophi), a brain, a dorsal antenna, a stomach (dark red in these pictures), a cloaca and toes ending their feet. This species, and many others, even has a pair of eyes that are visible as orange specks above its brain on the back of its head. The questions of why such a tiny animal would need seemingly binocular vision and what it can actually see are, of course, open to endless speculation.

bdelloid2

The animal on the left is feeding with its corona fully open. The beating of the cilia along the edges of the corona continuously pulls into the rotifer’s mouth water along with its food suspended in it: bacteria, algae and tiny organic debris. The animal on the right has closed its mouth and withdrawn its corona into its head; a ciliated sucker-like proboscis, the rostrum, is now at the front. The rotifer is crawling, like an inchworm, by alternately attaching the toes at the end of its foot and the rostrum on the substrate. Its antenna, an organ of unknown function, is sticking up from the top of its head.

Bdelloid rotifers live in ponds, lakes, creeks, wet soil, mosses, leafy lichens, bird baths and any other place where water may accumulate even intermittently. They are one of the main consumers of bacteria in waste water treatment plants. The individual who posed for my pictures did come from the bird bath in my backyard (and went down the toilet to the local WWTP).

Bdelloid rotifers (class Bdelloidea), with about 350 or so known species, have one characteristic that makes them stand out among all other animals: they are the largest group of animals that reproduce exclusively by parthenogenesis1-3. Every individual bdelloid is a female that produces unfertilized eggs from which more females hatch and so on. There is no published record of a male bdelloid having ever been observed.

Another characteristic that they share with some other microscopic creatures, such as tardigrades and nematodes, is that they can survive complete desiccation for long periods. Before I switched to snails, I worked with bdelloids for several years. I was really fascinated (I still am) with their ability to remain alive in a dry state. In a series of experiments4, I demonstrated that they could be stored alive at -20 °C and <1% humidity for at least up to 18 months.

Every November I empty out the bird bath, dry it and bring it inside. Every April I put it back out, fill it and invariably the same bdelloids return. I will, one day, figure out their secret.



1. Judson, O.P. & Normark, B.B. 1996. Ancient asexual scandals. Trends in Ecology & Evolution 11:41-46.
2. Welch, D.M. & Meselson, M. 2000. Evidence for the evolution of bdelloid rotifers without sexual reproduction or genetic exchange. Science 288:1211-1215.
3. Birky, C.W. 2004. Bdelloid rotifers revisited. Proceedings of the National Academy of Sciences 101: 2651-2652. pdf
4. Örstan, A., 1998. Factors affecting long-term survival of dry bdelloid rotifers. Hydrobiologia 387/388:327-331.―Reprints available! E-mail your postal address to me (please put reprint in the subject line). Sorry no pdfs.

24 October 2005

Snail shell terminology 3

The edge of the shell that surrounds the aperture is the lip (sometimes called the peristome). The morphology of the lip of the shell of an adult snail is an important taxonomic character. The lip could be the same thickness as the rest of the body whorl (below, left). In such cases, it is referred to as a simple lip. In many species, however, when the snail is nearing the end of its growth, the lip of its shell considerably thickens. Thickened lips usually flare out and are referred to as being reflected (below, right).


Anguispira fergusoni (left) and Mesodon thyroidus (right), both from Maryland.

In some species a rib forms inside the body whorl immediately behind the lip. An example of this is shown below.


Zonites casius from Turkey. There is a prominent rib within its lip.

Many species of snails thicken the lips of their shells as they mature reproductively. Once their lips thicken, such species stop growing further and are said to have determinate growth. In contrast, snails whose shells retain a simple lip after they mature may continue to grow as long as they live, although their growth rate seems to slow down as they get older. They are said to have indeterminate growth. It is difficult to tell when a snail with indeterminate growth becomes sexually mature without dissecting it.

Mesodon thyroidus has determinate growth, while Anguispira fergusoni has indeterminate growth. But, it is difficult to categorize the growth pattern of Zonites casius. Species like Z. casius sometimes resume growing after they have built a rib inside their lips.


To be continued...

Snail shell terminology 1
Snail shell terminology 2
Snail shell terminology 4

22 October 2005

Papers read this week

Joyce, W. G. & Gauthier, J. A. 2004. Palaeoecology of Triassic stem turtles sheds new light on turtle origins. Proc. R. Soc. London B 271:1-5.
I started reading this paper with some hesitations, because I don't know much about either turtles or skeletons in general. But the paper turned out to be easy to follow and understand.

The authors first demonstrated that the forelimbs of extant turtles reflect their habitat preferences, with short-handed turtles being terrestrial and long-handed turtles being aquatic. Then, they applied this analysis to fossils of two species of ancestral turtles from the Triassic. Based on the results of this analysis, they conclude that although the last common ancestor of all living turtles lived in fresh water, the original turtles that came before (the turtle stem lineage) lived on land.

Several years ago while looking for snails, I chanced upon an almost complete turtle skeleton that I meticulously collected. One of these days, I am going to use those bones to teach myself about the turtle skeleton and write a post about it.

Strathdee, A. T. & Bale, J. S. 1998. life on the edge:Insect Ecology in Arctic Environments. Annual Review of Entomology 43:85-106.
The Arctic invertebrate fauna is low in species diversity as well as population densities. This paper discusses the adaptations in morphology, behavior, life cycles and physiology of the Arctic insects that enable them to survive the harsh Arctic environment.

I read this paper not because I am studying the Arctic fauna, but because I have a specific interest in the land snail fauna of high mountains. I believe that there may be parallels between the evolutionary paths taken by the Arctic and montane invertebrates, including snails.

And a series of short, old papers from the Nautilus that I photographed two weeks ago at the Mollusk library at the Smithsonian's Museum of Natural History. They are always fun to read in the train on the way home from work.

Archer, A. F. 1942. Pine woods as adequate habitat types for land mollusca. Nautilus 55:94-97.
The author collected several species of snails in various types of pine woods in Alabama.

Marsh, P. L. 1942. Zoögenetes [sic] harpa (Say) in the Rocky Mountains. Nautilus 55:97-98.
I have written about the intriguing distribution range of Zoogenetes harpa. The author gave records of this species from two locations on the Rocky Mountains. According to his experience, Z. harpa was rare and never present in large numbers.

Ingram, W. M. 1942. Food habits of Haplotrema minimum Ancey and habits of associated mollusks on the Mills College campus. Nautilus 55:98-102.
Haplotrema minimum, a carnivorous land snail, was observed to feed on various species of snails, including juvenile Helix aspersa, a species introduced to California from Europe.

21 October 2005

Relief reversal effect


The picture shows paw prints of possibly a dog and a racoon. When the picture is rotated around its horizontal axis, the impressions in the original now appear as if they were reliefs on the surface of the sand ("negative" relief becomes "positive") and vice versa.


The reason for the apparent reversal of relief is explained at this site: "If a feature has positive relief the shadow will fall on the far side (away from the sun). If the feature has negative relief the shadow will fall on the near side (toward the sun)."

This is a well-known effect with practical uses. For example, Blaker1 explained, long before digital photography, how one can create a photograph of the inscription (positive relief) on a seal (when the seal itself is missing) by photographing its impression (negative relief) and then by reversing the film during printing.


1. Blaker, A.A. 1977. Handbook for Scientific Photography (pp. 223-224). W.H. Freeman & Co.

20 October 2005

Land snails of Turkey: Idyla bicristata (Pulmonata: Clausiliidae)


The ruler is in millimeters.

This species has so far been found only at a few disjunct locations in western Turkey. The specimens pictured above are from the vicinity of Manisa. Neubert published a drawing of the genitalia of a specimen from near Bursa1.

As in most clausiliid snails, there are several folds and lamellae in the aperture of the shell of this species and when the snail is fully withdrawn into its shell, the opening in the back of the aperture is blocked by a movable plate, the clausilium. Idyla bicristata has a so-called G type (Graciliaria type) organization of its clausilium and the associated lamellae.


Aperture of the shell of Idyla bicristata with the palatal wall removed; c: columellaris, cm: clausilium, p: parietalis, sc: subcolumellaris. The clausilium is in its closed position.

The evolution of the clausilium in the Clausiliidae is the subject of ongoing research. In future posts I will return to these interesting snails.


1. Neubert, E. 1995. Note on some genera of Clausiliidae from Turkey.
Zoology in the Middle East 11:101-108.

19 October 2005

Puzzling Wednesday

Four black cows and three white cows give as much milk in five days as three black cows and five white cows give in four days.

Which color cow gives more milk per day?

(Assume that the daily milk output of each cow is constant and the same for each black cow and each white cow.)

I will post the solution tomoorrow.


Slightly modified from puzzle #21 in C.R. Wylie, Jr., 101 Puzzles in Thought & Logic, Dover Publications, 1957.

18 October 2005

Free-access Journals and newsletters on insects and their relatives


Harlequin Bug (Murgantia histrionica), family Pentatomidae (stink bugs)


Journal of Insect Science
An electronic journal published by the University of Wisconsin Library Digital Press.

Florida Entomologist
Published by Florida Entomological Society.

Journal of Entomology
Published by the Asian Network for Scientific Information.

Journal of Arachnology – spiders!
All issues older than one year are free.

Acarology Bulletin – mites!
Newsletter of Systematic and Applied Acarology Society.

17 October 2005

Snail shell terminology 2

On the bottom (dorsal) side of a shell is its umbilicus. The shape and the diameter of the umbilicus is usually a species-specific character.

The umbilicus may be completely open (below, left), or partially covered by the lip (below, center), in which case it is referred to as rimate, or completely covered by the lip (below, right).


The shells of Haplotrema concavum (left), Mesodon thyroidus (center) and Neohelix albolabris (right). (Shells are not to scale.)

The umbilici of juvenile shells are always open. In N. albolabris the umbilicus is gradually covered by the edge of the lip as the snail matures.


To be continued...

Snail shell terminology 1
Snail shell terminology 3
Snail shell terminology 4

15 October 2005

No. 120884


A week ago when we were working at the land snail collection of the Smithsonian's Museum of Natural History, I went thru several drawers of clausiliids. This particular lot, obviously a very old one, especially attracted my attention.

I wasn't familiar with the species, there was no collection date, and the location, given only as China, was not of much use. Nevertheless, there was something alluring about these two shells, in an old box neatly tucked in graying cotton—as if they were some priceless gems.

14 October 2005

Papers read this week

Baur, A. & Baur, B. 2005. Interpopulation variation in the prevalence and intensity of parasitic mite infection in the land snail Arianta arbustorum. Invertebrate Biology 124:265-272.
The parasitic mite Riccardoella limacum lives in the lungs of land snails where it sucks its host's blood. The authors examined the prevalence of mite infection in 997 adults of Arianta arbustorum from 11 natural populations distributed over an altitudinal gradient ranging 335-2360 m in Switzerland. No infected snails were found in 7 populations, while in the remaining 4 populations the prevalence of mite infection ranged 45.8-77.8%. Interestingly, parasitic mites did not occur in snail populations situated at elevations of 1290 m or higher. The authors speculate that the snails' hibernation period may be too long at high elevations for mites and their eggs to survive.

Brodie, R.J. 2005. Desiccation resistance in megalopae of the terrestrial hermit crab Coenobita compressus: water loss and the role of the shell. Invertebrate Biology 124:194-201.
The hermit crab Coenobita compressus undergoes larval development in the sea and then moves to land as a megalopa (a juvenile resembling an adult), where it metamorphoses and remains for the rest of its life. Among other things, the author demonstrated that megalopae with shells survived desiccation much better than those without shells. In marine hermit crabs, the shell protects against predators. And because shell-wearing behavior predates land invasion, the author considers shell-wearing a pre-adaptation to terrestrial life, where the shell also protects against desiccation.

I will post more about this interesting paper in the near future.

Parmakelis, A., Pfenninger, M., Spanos, L., Papagiannakis, G., Louis, C. & Mylonas, M. 2005. Inference of a radiation in Mastus (Gastropoda, Pulmonata, Enidae) on the island of Crete. Evolution 59:991–1005.
I have written about the land snail genus Mastus before. In this study, the authors present a molecular, conchological and anatomical study of what seems to be a radiation (a rapid increase in species number) in Mastus in the Aegean archipelago, especially on the Island of Crete where there are 16 endemic species of Mastus. To explain the diversity of the Cretan Mastus species, they propose an allopatric nonecological radiation process that took place about 7 to 9 million years ago soon after the formation of the so-called mid-Aegean trench that separates the Turkish mainland (and the nearby islands) from the Aegean archipelago.

One puzzle that remains to be solved is the presence of 2 of the species (M. carneolus and M. etuberculatus) both on the Aegean archipelago and on the Turkish mainland across the mid-Aegean trench.

I will also post more about Mastus in the future.

Triantis, K.A., Pokryszko, B.M., Vardinoyannis, K. & Mylonas, M. 2004. A new species of Truncatellina (Gastropoda: Vertiginidae) from Mount Ossa (=Kissavos) (Greece). Journal of Conchology 38:393-397.
The description of Truncatellina cameroni, new species, from Mt. Ossa in Greece is given. It is the largest known species in the genus (holotype shell height: 3.17 mm).

Taylor, E.W., Sweeney, M.P. & Counts, C.L. 1977. Use of empty gastropod shells (Polygyridae) by pseudoscorpions. Nautilus 91:115.
I have written about pseudoscorpions. I frequently find them among recently collected empty snail shells. In this half-page paper, the authors reported collecting 2 species of pseudoscorpions from empty shells of Neohelix albolabris and Mesodon thyroidus in West Virginia. The authors speculated that the snail shells may offer protection to pseudoscorpions from weather extremes and predators.

13 October 2005

The biggest of them all: Tridacna gigas

Back in August I posted a picture of a Pisidium, a tiny clam (family Sphaeriidae) that was about 2 mm long. And now here is something from the opposite end of the size spectrum: Tridacna gigas, the largest known extant mollusk species. The shells of this species can grow up to 1.5 meters in length.


The pen provides a scale.

This particular specimen sits in the elevator lobby on the 3rd floor of the Smithsonian’s Museum of Natural History. It is an area normally closed to the public, and because of that nobody gets to see it except the people who work there. I was there last Tuesday working in the mollusk library, which is also on the 3rd floor. While waiting for the elevator on my way down I snapped this picture for all to see.


More information on Tridacna gigas:
Animal Diversity Web
ARKive

12 October 2005

No scaredy-deer


We live near Black Hill Regional Park in Germantown, Maryland, where there is a sizeable population of the white-tailed deer (Odocoileus virginianus). Because the park is surrounded by residential areas, hunting is not allowed. However, every winter a few nights after the park closes, the park police carries out a deer "population control" operation.

Despite the lack of regular hunting, the deer in the park are quite wary of humans and normally run away as soon as they spot someone approaching. These two that I encountered one afternoon about 10 days ago were, however, unusually tame, especially the one in the front. I approached within about 5 m of it before it darted off (I was on a boardwalk slightly above them).

Not surprisingly, deer bones are also common in the woods. For a while, my son was quite interested in bones, so we used to pick up every one we found. Now, we have buckets of deer bones in the backyard that frequently get pillaged by mysterious nighttime intruders. They leave behind gnawed bones scattered in the yard. I guess we are the calcium depot for the local wildlife. I wonder what the neighbors think.

milkriverblog has more deer stories.

11 October 2005

Snail shell terminology 1

ShelTerm1
Borlumastus yildirimi from Turkey

The aperture is the opening of the shell, whereas the apex is the very top of the shell. The last whorl is called the body whorl, because when the snail's foot is out, most of the rest of its body will be in there. The body whorl is also the ultimate whorl and the one above it is the penultimate and the one above that is the antepenultimate whorl. The rest of the shell above the last whorl is referred to as the spire. Suture is the line that forms along any two overlapping whorls.

protoconch1
Zonites casius from Turkey

The shell a snail builds before it is born is the protoconch and the shell it builds afterwards is the teleoconch. There is usually a break between the protoconch and the teleoconch across which the microsculpture of the shell may change. The sharp radial break visible in the picture of Zonites casius (above, left; white arrow) marks the point where the protoconch (above, right; blue outline) ends and the teleoconch begins. The picture below shows a shell of Anguispira fergusoni where the end of the protoconch is marked by a change in the microsculpture (arrow).

protoconch2
Anguispira fergusoni from Maryland


Snail shell terminology 2
Snail shell terminology 3
Snail shell terminology 4


10 October 2005

Gastropods for posterity

alcohol1

A reader in a comment to yesterday's post on snail shells in museum collections, wondered if the snails' bodies can also be preserved. Why, of course, we do it all the time.

We didn't visit the alcohol collections last Friday, so today's pictures are from my collection. Although I don't like killing them, I do have a large collection of pickled snails and slugs in my basement (yes, it's all in the name of science).

The preservative of choice is 70% ethyl alcohol (ethanol), the remainder being water. I add a little bit of glycerol to my alcohol solutions to prevent the specimens from drying out should the alcohol evaporate (glycerol absorbs water and doesn't dry). To preserve their DNA, the specimens are kept in 95% ethyl alcohol.

Isopropyl alcohol (rubbing alcohol) would also preserve soft tissues, but it tends to make snails' bodies too hard for dissection. Tim Pearce says ethanol concentrations higher than about 70% also harden tissues, but it is a tradeoff with preserving DNA.

And this one is for Celeste, to show her that the little jars she's been saving for me are indeed being put to good use. This jar once held red raspberry preserves.

alcohol3

09 October 2005

Where have all the meadows gone?

193967

The purpose of our visit to the land snail collection of the Smithsonian's Museum of Natural History last Friday was to look for unpublished records. Tim was interested in records from Pennsylvania and New York and I was looking for records from northern Maryland, especially from the vicinity of D.C. (and also from Turkey). Such records not only help us create more complete distribution maps of the recorded species, but they also give us an idea of what the area may have looked like when the collection was made.

The picture above is that of a collection of Gastrocopta tappaniana made on May 1, 1904, in an "open meadow" 200 yards west of Chevy Chase Circle in Maryland. The green dot I put on the current map of the area below shows the approximate location of the meadow 100 years ago. The meadow and the snails are long gone.

chevychase

Incidentally, the collector was presumably Paul Bartsch (1871-1960), one of the former curators of mollusks at the Smithsonian.


08 October 2005

A day at the museum with friends I've never met

I have a friend I've never seen.
He hides his had inside a dream.
Someone should call him,
and see if he can come out.

Neil Young, Only love can break your heart, 1970

Spent yesterday with Tim Pearce (a friend I've seen many times) going thru the land snail collection of the Smithsonian's Museum of Natural History. It was a perfect activity for a rainy day.

There is something fascinating about looking at old natural history collections, especially if one is familiar with the organisms in the collection, and also if those little labels that come with each lot have lots of stuff written on them (and on their backs).

The older the lot is the more intriguing it becomes. I try to decipher the handwriting, figure out the location and am often puzzled by the identification, which is almost always outdated, if not plain wrong.

And every time I come across the name of a long-dead collector that I recognize, it is like encountering an old friend I have never met.

clausilia

The lot of clausiliids above attracted my attention, because, even though it was not dated, the spelling of Istanbul as Stambul on the green piece of paper suggested it was quite old. If you look closely at the label, you will notice in the middle of the bottom line the word "over", indicating that there is more on the back. What was on the back was a true surprise.

label

I recognized the two names immediately from a 1863 paper in my collection1. The author, Albert Mousson, titled his paper, "Coquilles terrestres et fluviatiles, recueillies dans l'Orient par M. le Dr. Alex. Schläfli".

It is a small world.


1. Mousson, A. 1863. Vierteljahrsschrift Naturforschenden Gesellschaft, Zürich, 8:275-320. The title, loosely translated, means "Terrestrial and freshwater mollusks, collected in the Orient by Dr. Alex. Schläfli."


06 October 2005

American Bullfrog (Rana catesbeiana)

bullfrog

I photographed this frog about a month ago next to a creek in College Park, Maryland. First I thought it was a Northern Green Frog (Rana clamitans melanota), but White & White1, indicates that the Green Frog has a pair of distinct dorsolateral ridges, which this specimen lacks. According to the same source, in the Bullfrog the dorsolateral ridges are lacking, but "a distinctive short fold of skin begins just behind the eye and curves down immediately behind the tympanum." A fold matching the description is clearly visible in the picture.

This website explains that "Like many species of Rana, the tympanic membrane is helpful in determining the gender of the individual. In females, the membrane will be roughly equal to the size of the eye and in males the membrane will be considerably larger." Based on the size of its tympanic membrane, this specimen is a female.

This species is native to the central and eastern United States and the southern portions of Ontario and Quebec. It has also been introduced into southern Europe, South America, and Asia.

More information on the American Bullfrog:
Animal Diversity Web


1. White & White. 2002. Amphibians and Reptiles of Delmarva. Tidewater Publishers.


New issue of the Archaeo+Malacology Group newsletter

The AMG Newsletter No. 8 (and the previous 3 issues) is available here. This issue contains two articles on freshwater mussels in Israel, one on the identification and distribution of edible land snails in Turkey, a brief appreciation of the work of the late Professor John ‘Snails’ Evans and a note about an unusual fake cowry from a grave in Hungary. There are also some requests for information, abstracts of recent papers and notices of forthcoming conferences.

04 October 2005

A horse pretending to be a dog

horse

Photographed on the Beltway going home from Belt Woods last Sunday.


03 October 2005

Down among the old trees


Is there anything better to do on a beautiful Sunday afternoon than to look for snails among ancient trees? That's exactly what I did yesterday in Belt Woods, the largest tract of old growth forest left in eastern Maryland.

I obtained a permit last Spring from the Maryland Department of Natural Resources to do a snail survey in Belt Woods, but Pam Cooper, the manager of Belt Woods, requested that I put off the survey until the end of August to avoid disturbing the ground-nesting birds. For one reason or another, I wasn't able to start the survey until yesterday. I am planning to go back there several more times before the winter comes. I will post updates here.


Here is Pam breaking her back to find shells for me.

Although the virgin forest at Belt Woods covers only about 45 acres, there appears to be a rich land snail diversity. Below is a Triodopsis (species to be determined), one of the most common snails in Belt Woods, crawling on my hand.

01 October 2005

Stalemate in the backyard


This happened about 10 days ago. Marissa-Cat, otherwise a hunter of crickets, decided to go after a chipmunk under the deck in the backyard. The short chase ended when the chipmunk disappeared under a pile of assorted pieces of wood. Rather then walk away, Marissa-Cat comfortably settled down on one side of the woodpile and started waiting patiently for the chipmunk to reappear, while the latter was exploring the secret passageways under the woodpile for a safe way out.

I entered the game when I decided to investigate. Now it was a threesome. The chipmunk, who was peeking out from among the pieces of wood (visible near the lower left-hand corner), didn't dare come out, because it could see me; Marissa-Cat, who couldn't see the chipmunk, but knew something was up, wouldn't move her eyes away from the woodpile and I, with camera ready, wouldn't leave, because I was hoping to photograph a dramatic finale.

For a long time nothing happened, not a whisker moved. It's amazing how patient and insistent these animals could be when it is a matter of life or death for them. In the wild, one mistake could end the life of either the hunter or the hunted; the predator from starvation, while its potential prey, from being a meal to the predator.

Finally, I got tired of waiting and ended the game. I went inside and got a dish of chicken pieces with which I was able to entice Marissa-Cat out. Once she came out, I grabbed her and brought her inside. In the meantime, the chipmunk, scared by my approach, went back under the woodpile.

We are hoping for more action next time.