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.


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