Category Archives: Snails

Gastrodonta interna on the prowl

Early this morning in Shakerag Hollow the humidity was so high that water droplets drifted through the air. We were walking in a halo.

The settling water ruined the invisibility of spider webs. This one hung ten feet above the ground.

Snails and slugs were active, especially around the bases of dead trees. Probably at least half of the species of land molluscs in this forest dwell in or under dead wood.

Gastrodonta interna, the “brown bellytooth,” was particularly abundant. The small ribs on its body whorls make the shell looks like a tightly coiled rope. The shell is small, about 7 mm wide, and has about 8 or 9 whorls.

Xolotrema denotatum and others at the Powdermill Nature Center

A dozen snail enthusiasts joined the American Malacological Society’s field trip to Powdermill, ably led by Tim Pearce, Head of the Carnegie Museum’s Section of Mollusks.

Xolotrema denotatum was one of the twenty five species that we found. I have been wanting to see this species for some time. We have its cousins, Xolotrema obstrictum and Xolotrema caroliniense, around Sewanee; both of these species have beautiful shells.

Xolotrema denotatum at Powdermill – note the very hairy covering to the shell. This is formed by the protein coating of the mineral shell.

Xolotrema denotatum seen from the side.

Xolotrema caroliniense shell from Sewanee

Xolotrema obstrictum shell from Sewanee.

A swarm of malacologists

I found these snail eggs hiding under a piece of fallen rotting wood on the forest floor:

The whole cluster is about half an inch across. I’m guessing they are Mesodon or Mesomphix eggs.

Some spectacular fungi were growing under rotting bark.


“Indian pipe” plants were poking up from the leaf litter.

Monotropa uniflora, a parasite on fungi that live in symbiosis with tree roots. So, this plant parasitizes trees through an intermediary.

Although Monotropa is only four inches tall, it is a relative of blueberries and azaleas (in the plant Family Ericaceae). It has lost is chlorophyll, giving it another common name, the "Ghost plant."

You can see more photos from the trip at Aydin Örstan’s blog, The Snail’s Tales.

Live Ventridens pilsbryi

This small species of woodland snail caused some consternation last year when my students, Keri Bryan and Maggie Shipley, found several in the forests around here. The shells keyed out to Ventridens pilsbryi, but we were working with dead shells, not live individuals. One diagnostic character is the color of the body — “pale yellowish with some gray along the back” (instead of “dark” as in the gularis group) according to Hubricht’s original description.

Yesterday I found a live one in some leaf litter samples that students in the Sewanee Environmental Institute had gathered. The body is light, although not yellowish.

Ventridens pilsbryi showing some body

The shell has seven or eight whorls

The two characteristic lamellae (raised ridges running back into the shell) are visible in this empty shell.

Shakerag Hollow

At 6:30am it was already muggy. The thickness of the haze behind this indigo bunting is impressive.

Indigo bunting above Roark's Cove, TN

In the cove forest, the tree canopy is so thick that only a few flowers try to squeeze out their living from the meager light of the understory. Most of the spring wildflowers — Hepatica, Trillium, spring beauty — are dying away or setting seed. Violets and spiderworts buck the trend and are fresh and vital.

Canada violet -- grows ankle-high

Wideleaf spiderwort -- their stems grow two or three feet tall with a thumbnail-sized flower at the top

Several snails traversed the moist forest floor. This shell is of their enemy, the flesh-eating Haplotrema concavum snail. This species tracks down other snails by following their scent, then drags them away to eat.

Haplotrema concavum, the "gray-footed lancetooth." This species has a very wide, open coil on its underside.


A few doors down from the White House sits the largest collection of molluscs in the country, including the holotype of the “Cumberland tigersnail,” Anguispira cumberlandiana, a species that was first described in 1840. The holotype is surprisingly colorful and fresh-looking, despite its age.

Anguispira cumberlandiana holotype

Anguispira cumberlandiana holotype, bottom view. The streaks on the base of this shell are confounding -- they are seldom found in other members of the "same" species and are very much like the streaks on the base of Anguispira picta shells.

Specimen labels, including those from the 1840s

Bob Hershler, Research Zoologist and Curator of Mollusks, was a very helpful and welcoming host and was kind enough to let me look through some of the other type specimens — the Smithsonian has cabinets full of extraordinary material.

Following up on previous comments about museum street art, the entrance to the museum had no snail sculptures, but some tree ferns appeared as I was working inside. They were on the back of a truck when I walked in, no doubt coming to add summertime botanical interest to the entranceway. I think they are Dicksonia, a south-east Australian/Tasmanian species.

Australia comes to Washington -- tree fern in front of the Smithsonian


After my last blog post about the lack of street art snails, I was dumbfounded to walk up to the Academy of Natural Sciences in Phildelphia and see this:

Snail outside ANSP (the red brick building behind). There seems to have been some convergent evolution with bryophytes.

The ANSP also has cool dinos in front:

Deinonychus at ANSP


Thanks to the kind welcome of Amanda Lawless, Research Assistant in the Department of Malacology, I was able to examine more Anguispira specimens, including some from Sewanee collected in the mid-19th century when Sewanee was known as “University Place”:

Old Skool malacology in Sewanee

More holotypes. This one is from a species endemic to one small part of Kentucky:

Anguispira rugoderma holotype

A cornucopia of tigersnails!

Anguispira holotype-fest

Ooo la la, Holotypes galore at the Carnegie Museum in Pittsburgh!

Anguispira picta holotype, Carnegie Museum

Specimen labels from Anguispira picta holotype, Carnegie Museum

Anguispira alabama holotype, Carnegie Museum

Drawer full of type specimens, Carnegie Museum

These are the original specimens from which the venerable G. H. Clapp described the rare tigersnails (genus Anguispira). These snails live in the rocky limestone outcrops that jut from the low mountain slopes around Sewanee.

After studying these snails for several years it was a treat to see and photograph these beautiful shells. The “holotypes” are the individual specimens to which the name of each species is attached – the throbbing heart of all of biology because without species names, the life sciences could not operate. Yay for taxonomy!

Jia Pan and I have been sequencing the snails’ mitochondrial DNA to peer into their evolutionary history and present-day genetic diversity. Our genetic work suggests that some previously undescribed forms may lurk in the shady mountain coves – we’re now checking to see how the appearance of the shells matches (or not) the genetic information. Thank you to Tim Pearce, Asst. Curator & Head, Section of Mollusks at the Carnegie Museum of Natural History for making my visit such a pleasure.

Surprisingly, the museum chose not to feature Anguispira in their street art:

Diplodocus, Carnegie Museum

Diplodocus nameplate, Carnegie Museum

Triceratops in full breeding colors, Carnegie Museum