Posts Tagged 'Gastropoda'

All Creatures Great and Small

Mostly small. And mostly slimy (cue Monty Python).

More tidying up in the Back 40 in preparation for winter. My backyard is a Brutalist expanse of poured concrete, so I use numerous pots for planters. All were salvaged from the street. There’s also a found-on-the-sidewalk wooden box, festively decorated with painted balloons. While moving this the other day, I found these creatures beneath it. Generally shunned by the dainty among us, these creatures of the shady damp — slug, snail, pillbug — are key to decomposition and recycling nutrients, and thus making the world go ’round and ’round. An earthworm, three more of the disk snails pictured in a previous post, a centipede, some smaller pillbugs, and several way-too-small-to-figure-out things were under there as well.
A closer look at the Common pillbug, Armadillidium vulgare, also known as common woodlouse or roly-poly. When disturbed or otherwise bummed out, these roll up into a tight armored ball. Love the overlapping plates here. These are not insects, btw; they’re crustaceans.
I find this land snail strangely beautiful: the contrast of amber shell and blue grey gastropod itself. The shell is about 1/4th-inch across, so bigger than the disks, and much smoother. The umbilicus, which is on the other side of the shell, is very deep (like Jimmy Joyce’s Omphalos). I think it’s a member of the family of glass snails, Oxychilidae. It looks like it might be Oxychilus draparnaldi, but they are supposed to be rather larger, so I’m not sure.

“We must not feel a childish disgust at the investigations of the meaner animals. For there is something marvelous in all natural things.” — Aristotle

More snails

I found this little specimen in North Andover, MA. I think it’s Oxyloma retusum, the blunt ambersnail.

This is a fairly similar animal, but I’m not sure it’s the same species since the shell is not glossy or amber. What do you think? I found this one on Nantucket, MA. Is that snail turd there?
Meanwhile, this is an operculum. It’s the door, essentially, to a snail, attached to the bottom of the foot so that when the snail draws inside the shell, it can seal itself in. Not all snails have these, but the mystery snails of Green-Wood Cemetery do. Something scarfs these snails up around the edges of the Valley Water, but the predator does not like the thin shells, which are usually shattered. A couple of these operculum were recently lying around as well. I still think these are Cipangopaludina chinensis, formerly known as Viviparus malleatus, but I’m happy to be schooled if I’m wrong.

Natural Object: Whelk Egg Case

You may recognize this if you live on the east coast of the U.S. south of Cape Cod: it’s a whelk egg string. Here in the NYC region, we have two types of big whelks, the channeled and the knobbed. The knobbed is the state shell of New Jersey and Georgia, should you ever be asked. (State shells?) Down south, you may also come across the lightning whelk and the pear whelk. Up north in the New England states north of Cape Cod, fugetaboutit!

The string pictured was found on Nantucket. It’s from a knobbed whelk. I grew up seeing these things on the beach, but it was not until last year that I learned that the individual cases on the string can be full of tiny whelks.
Yes, these are in the palm of my hand; the sand (which spilled out with them) is also for scale. What you see is the contents of just one of the coin-sized cases on the string. Successful whelks can grow to be 5-9 inches long.

More details here and here.

UPDATE: The search term feature of WordPress allows me to see the words and phrases that lead people to this site. “My dog ate a whelk egg case” was one. The strings look and feel pretty crunchy, but I think the dog will be OK. I used to know a dog that ate shampoo and soap and he was OK, albeit crazy.

Snail Tales, part III

For a change of pace, a fresh water gastropod, which means I did not find these in the Back 40. The species is a Brooklyn resident, however: I took this photo at the Valley Water in Green-Wood. I think the snail is Viviparus malleatus, the Chinese mystery snail, a.k.a. the Japanese trapdoor snail. (Like many of us, these come from somewhere else.) What you see above is, I think, only half the size of the shell of the living creature. I was lucky to find this much. Mostly, it’s all shards. The pond’s stone edge is littered with broken shells. Something eats these critters like no tomorrow. The shell is particularly thin, so it seems to be easy to crack, spear, smash.

Another Back 40 Gastropoda

Leopard slug, Limax maximus. This species is native to Europe, but is now found in many other parts of the world. I wasn’t aware until just now that this member of the Gastropoda actually does have a “shell,” only it is internal, underneath the shield, which is that spotted portion at the top front end. I think the shell itself is that obvious hump there at the right end of the shield. (Um, no, I didn’t touch it to find out.)
Last year in Inwood Park at the northern tip of Manhattan, during a night hike, we watched these things mate. Whoa! Wikipedia has some images and drawings of this. I’d already seen the episode of Life in the Underbrush that showed this, so I was prepared, but still, to see it live was amazing. Let’s let the inimitable David Attenborough (OK, he’s actually pretty imitable) take it from the top:

There are more things in heaven and earth, readers, than dreamed of in our philosophies.

Snail tales, part II

They leave a trail of slime and eat your plants, or at least some of them do, but gastropods, with their shells, love darts (!), and hermaphroditism, are as remarkable as any other life-form. (Until you’ve seen slugs mating, my friend, you have not lived. A future post will get sluggy. )
Last autumn, while cleaning up the Back 40 in preparation for winter, I found this snail underneath one of my pots. It’s posing on a glass topped table. 3/8ths inch long shell, with a deep umbilicus. I’m not sure what species it is.

This stripped specimen was also found in the Back 40.

Here it is surrounded by other examples of its species, Cepaea nemoralis, the rest of which were found at Dead Horse Bay or Jamaica Bay or here or there. The species is obviously pretty polymorphic in coloration, but all have the brown lip that gives them one of their common names, the brown-lipped snail. Except for that one on the unfocused right, which isn’t like the others:
This one I’m also not sure of. It doesn’t have a brown lip but definitely does have an umbilicus, which C. nemoralis lacks. (D’uh! and I also don’t remember where I found it.) Oh, well, it’s here for comparing and contrasting.

To recap: the unknown species in the first image above; the C. lubrica in the previous post; the stripped C. nemoralis; and the tiny D. rotundatus that I found last month, make for four different species of snail in the Back 40.


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