Tuesday, July 12, 2016

City of the left-handed snails

kw: natural history, natural science, museums, collections, photographs

Alex, the Collections Manager of Mollusks at the Delaware Museum of Natural History has been a pretty busy guy lately. He has a few volunteers taking care of such tasks as sorting shells and labeling them after he has identified them. Two volunteers can be seen in the background of this picture; I caught him putting some boxes of shells away now that their labeling has been completed.

Each volunteer has a project, or a series of short-term projects, so they stay out of each others' way. One man about my age comes in two days each week, and most recently he has been replacing storage boxes. When the museum began operations in the 1970's the typical storage box for a collected lot of sea shells was a stiff paperboard box. Years later it was learned that the rather ordinary paper used for these boxes is a little acidic because of the lignin that accompanies the cellulose in all wood products. Acid is a no-no around sea shells (and a great many other kinds of museum specimens); sea shells in particular are soluble in acids! So this volunteer will take a box, say a #3 box that is 3x3 inches, remove the shells and labels, and put them into an acid-free box of the same size.

I started out at the museum as a volunteer, after retiring from a local company. Because I had been a computer professional, and I am conversant with databases and how they work, I was soon doing data cleansing and other tasks they needed for properly keeping the records of all their shells (220,000 lots with an average of 7 or 8 shells each). Now as a part-time employee the work I do is a little more advanced.

But back to Alex's volunteers. A museum cannot function well without them. Each volunteer may work only 10-20 hours weekly, but if there are five or six or more, they do the work of an extra one or two full-time employees. A collections manager would get less than half as much work done in a year without volunteers.

Just around the corner from the spot shown above I found an entire cabinet full of large whelks (big sea snails; they make great eating!) of the genus Sinistrofulgur, and family Busyconidae, the true whelks. They were recently put away as the result of another project. (I don't know if the beginning of Busyconidae is pronounced "busy", or if it comes from a name with some other pronunciation. I'll find out.) The type genus of the family is Busycon, and I'll show a few of them in a moment.

The reason for the name Sinistrofulgur is that all the shells of all the species in this genus are left-handed. See the pictures below to learn to tell whether a snail shell is right-handed or left-handed.

The shells in the picture at the left are of the genus Sinistrofulgur and are left-handed. The shells in the other picture are of the genus Busycon and are right-handed; the original name for this genus was Fulgur, so its sister genus of left-handed species naturally got the name Sinistrofulgur.

When you hold a snail shell so the spire is up, if the opening (aperture) is on the right, the shell is right-handed, and a left-side aperture means it is left-handed. Also, if you imagine that the point of the spire is like a screw, its "thread" goes in the proper direction to be screwed into something with what we think of as "right" twisting.

In the context of naming biological entities, "sinistro-" does not mean "sinister". It is not evil in any way. "Sinistro-" as a prefix means left-handed, and "dextro-" as a prefix means right-handed. Because most people (and most apes, for that matter) are right-handed, the Latin word for "right", dexter, also gained the meaning "skillful", as in "dexterity". We right-handed folk use our right hand for most skillful tasks and the left hand has a more supporting role. The Latin word for "on the left",  sinistralis, was not originally meant to be related to moral evil. But left-handed people were often regarded with suspicion, so "right" came to mean "good", as it often does in English, and "left" came to mean "bad" or at least, suspicious. This is meaningful in the context of the bloody old Roman society in which fighting with swords and shields was rather common. A left-handed opponent could more easily get his sword around your shield. While he might seem to be at the same disadvantage, he would have been practicing with right-handed sparring partners, while very few right-handed warriors had much chance to spar with a left-handed opponent.

But a left-handed snail is highly prized for its rarity, and a member of an entire left-handed genus, such as Sinistrofulgur, is even more sought after by shell collectors.

1 comment:

Anon Polymath said...

I read about left handed snails in Jules Verne book 20,000 leagues under the sea. Ever since I have been on the look out for one. But never found any. Was thinking of producing them artificially.