Posts Tagged 'Gastropoda'

Spring Cleaning Snails

snailsThree different specimens of our old friend Cepaea nemoralis.snail2snail3snail4The snail’s “foot,” which gave rise to the name for this whole class of Molluscs, Gastropoda, which means simply stomach-foot (and is anatomically incorrect; the stomach is in the portion of the animal that is inside the shell).snail5Just a size comparison with some other snails found during this clean up. The mm ruler looks bent because the macro lens distorts at the edges, either that or the omphalos of the shells draws gravity in like a black hole.snail6Unknown species on the left;Discus rotundatus on the right.

Natural Object: Moon Snail

Detail of the spire of a shell of an Atlantic moon snail, also known as a shark’s eye. Polinices duplicatus is found from Cape Cod to Texas. This one was found on the beach at Breezy Point, Queens, NYC.

Whelk egg cases

Telling your whelk egg case strings apart, Southern New England to Mid-Atlantic division:
This is the egg case of the channeled whelk, Busycotypus canaliculatus. Note how the edges of each individual capsule comes together as if pinched, giving each capsule a sharp edge.
This is the egg case string of the knobbed whelk, Busycon carica. Note how the edge of each capsule is flattened, like a sturdy coin.

Each capsule contains 25 or more tiny baby whelks in their tiny baby shells. Here are some of the channeled whelks who didn’t make it:In the palm of my hand. Each is about 3/16ths of an inch long. Check out this earlier posting for views of the baby knobbed whelks.

O, and telling your adults apart is straight-forward:The knobbed whelk, top, has knobs on its spiral. The channeled whelk (7.25″ long), bottom, has a deep groove in its spiral. Both these shells were found at Fort Tilden in Queens (the egg cases were found on Nantucket). Color of the shell can vary: NYC-local whelks don’t have the coral pink interiors you find in Massachusetts.

The phrase “whelk egg cases” and variations thereof, turns out to be one of the most popular internet searches leading to this blog. So this one’s for you, stranger.

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Not at all sluggish

I know you’ve all been eagerly awaiting the arrival of the first slug of the year in the Back 40, my concrete backyard. Well, here it is. (There were probably others, but as mostly nocturnal creatures, they’re hard to see.) The leopard slug, Limax maximus, slime-delivered. Disliked by gardeners, for they eat greens; loved by everything from owls to turtles to moles,, which eat them. For more on leopard slugs, check out my earlier post, which includes the now notorious David Attenborough Slug Sex Scene, banned in 20 countries and four U.S. states.

Winkles

Four shells collected at Cape Anne, Massachusetts. The three clustered around the illustration are Common European Periwinkles, Littorina littorea. This winkle, much savored by Old World palates, was first recorded in the Gulf of St. Lawrence in 1840, perhaps arriving via rock ballast in ships. Another source says they may have arrived much earlier, upon drifting logs before the Europeans themselves arived on more ornate drifting logs. However they got here, they’re now established on both U.S. coasts and they tend to be bad news for the ecosystem. We should probably be eating them, too.

The white shell on the left is an Atlantic dogwinkle, Nucella lapillus, one of the native species beset by competition and habitat transformation resulting from the abundance of European periwinkles.

Virgin Gorda Beachcombing

Various intertidal snails were found on old coral, mangrove roots, rocks, coconut shells.

Another beach

The Common slipper shell, Crepidula fornicata, a.k.a. boat shell, a marine gastropod, or snail, pilled up at the Jetties on Nantucket. A not particularly rocky area, the island’s surrounding waters present less than enough bases for these snails to attach onto, so they often attach to each other, in chains. The species name comes from the Latin fornix, meaning arched chamber, the same root as fornication.
The gulls think they’re delish.

An update 1/15/11: Many snail species are hermaphrodite. Crepidula species start out as male and then develop female characteristics as they mature. Also, the empty shells, a.k.a. Quarterdecks, are used commercially as a bedding for embryo oysters.

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.


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