Scalariform Shell

[kanin]

I'm just wondering if anyone have had any experience of the scalariform mutation? And also if it somehow could have any negative effect for the mutated snail?

I'm looking into breeding scalariform snails and I'm a bit concerned of the ethical aspects but all the info i've been able to find says that a mutated snail is just as healthy as a normal one .
If anyone have any ideas/arguments about this feel free to post this here as well.

-emil.

I'll post some links to pictures of scalariform snails for thoose who havent encountered the phenomenom. (these are not my pictures by the way)
www.gardenersworld.com/talk/blogs/post/rj-snails-09072008/img3.jpg
www.weichtiere.at/images/weichtiere/schnecken/weinberg/scalarid1.jpg
www.weichtiere.at/images/weichtiere/schnecken/weinberg/scalarid.jpg

[coyote]

I've not had any experience with this shell form, but I would assume that the snail's body is similarly shaped inside the shell. That may or may not be a source of health problems for the snail (having its internal organs stretched out like that). I don't think anyone has tried to breed scalariform snails, so there likely isn't going to be any information that says this kind of snail isn't healthy. That kind of information wouldn't come to light until several generations have been reared. It's also possible that breeding 2 scalariform snails together would not yield fertile eggs, though.

They are certainly very striking in appearance, so I understand the wish to breed them. I think it's something worth investigating further.

[kanin]

Yes, another problem is the rarety of this mutation. I think i might be able to get one or two wild caughts nemoralis but thats hardly enough to start a breeding projekt.

[lizzie97444]

aww it looks heavy on them but I wonder if it is for them
Are these really rare?

[kanin]

They're extremely rare, I think they're even rarer than sinistral mutations.

[Robert Nordsieck]

Hi there,

it depends, which species you are looking at, if sinistral mutations are rare, or not.
There is a page on sinistral shells, that I have written:

> The coiling of a snail's shell.

There also is a page on scalariform shells, that I have written, after a snail farmer I know had found a scalariform Helix pomatia in her pens (the pictures you posted) and I also was able to obtain pictures of a scalariform Cepaea nemoralis next to a normal one.


Normal and scalariform shell in comparison: Cepaea nemoralis. Picture: Gudrun Ruf.

> The scalariform shell.

Though you did mention that the pictures are not yours, I would prefer, if you post the page, not the picture, so it is not taken from the context of the page it was placed on.

But in principle, of course, you may take the pictures.

Kind regards
Robert

[kanin]

Sorry robert, just copy-pasted them directly of the search engine.

[Rachel]

never having personally kept or bred one I cant really say anything from personal experience, but I would think that as it (by my understanding) is a very rare fluke, most of the babies would be normal?

[kanin]

Yes, most probably. What I had in mind was to breed one scalariform C. nemoralis with a normal one and see if any of the babies would be scalariform aswell. If i can find the sclariform nemoralis again, it was sitting about 2,5-3 meters up on a wall in a friends garden but was gone a few days later.

[cepealove]

Id be intrested 2 c how you get on with that. I was thinking sinistral x dextral, but second thoughts i dont think thats possible? X

[fabrizio]

Very interesting topic... and I have read of an southern italian malacologist, from Calabria, that mated a scalariform Eobania vermiculata with a normal one (if I remember well), and at least part of the offspring came out being of the scalariform type!

-As to myself, I would like to try the same with Eobania or other species (Cepaea don't live right here), but never found a really scalariform shell till now... Yet I found some "incipient" scalarized Eobania, with a higher spire and some "de-packaging" of the coiling.
I have to quantify the degree of deviation, then mate together the more "deviant" ones, and repeat quantification/selection on the offspring, if I'll get any.

-Starting with a true despiralized snail would be still better and easier...

.Surely, as to "ethical" concerns, it must be said that such snails would be "handicap-bearers" in the wild, and for this reason there are almost no such shaped species... lest in protected or particular environments, as the depth of Baikal Lake, where a similarly shaped species, Liobaicalia sp., or some Caribbean Annularidae (Pomatiasidae), living hidden in protected calcareous crevices.

Obviously, a captive living specimen would be not affected by any "handicap", as protected and cared as long as its life will be.
So no sufferences should be carried with, I believe.

I just wonder, how the internal organs would change their shape; but there are so many shell shapes and types of spiralization, all of them compatible with the same basic anatomy, and all of them fully viable; just as these Cepaea (or Cornu, etc) seems to be. Otherwise, they wouldnot have reached maturity.

Please keep us updated with your researches and breeding programs; please note that even a single despiralized specimen would be good, to mate with a "normal" one.
Selection would start again within the offspring.

[cepealove]

So would the gene carry from the offspring or would the gene skip a generation? X x

[fabrizio]

As I read, the offspring has already the trait from the first generation, and it becomes attenuate if on of the parents is "normal"; but I think that by mating the more "deviant" offspring, a full despiralization can be obtained again with the 2nd generation.

[Robert Nordsieck]

Hi there,

@ cepealove: It is certainly possible to mate a sinistral snail with a dextral one, it is only more difficult for the snails.

There is a picture by Peter Leonhardt showing this very well:


Snail king (on the right) mating with a "normal" snail. Picture: Peter Leonhardt. Reference: www.helix-pomatia.de.

Besides: Ever thought about why Cornu aspersum is called that way? In 1778, Ignaz von Born, who also appears as Sarastro in Mozart's "The Magic Flute", described a horn shaped specimen of the brown garden snail, which is why it is called Cornu, the horn.

See here: The Cornu problem.

Kind regards
Robert

Kind regards
Robert

[cepealove]

I see i thought kings wer infirtile, but im guessing not.wow wouldnt it be amazing to have an albino king schaliform shell. . .

[coyote]

Wow, I'd love to see such a snail!

[fabrizio]

In fact, snail farmers have statistically an higher probability to find out a sinistral or a (more or less) despiralized snail, if they are watchful enough...

It would be wise and lucky, if they could then pass the mutated specimen to some caring "pet" snail breeder...

As Robert has shown us dx/sx mating is not impossible, even if it is not usually chosen in the wild, having anyway much less chances of being accomplished.

Yet once "fixed" a large enough "sinistral" population, following an uncertain and very long, time taking process, this premise could then rapidly become a sort of "genetic barrier" encouraging segregation ---> (sympatric)speciation, as it has been argued in the case of japanese Bradybaenidae genus Euhadra, whose extant five sinistral shelled species (among a total of 22 actually living species) seem to have just arisen in the said way.

[cepealove]

And you make that sound easy.

[crossless]

I have one!



It would be really interesting to see it's offspring if I find some eggs.

I think it would be easier to find eggs if I set free back to wild my Cepaea hortensis sripped one and 2 yellow shelled and Fruticicola fruticum or Bradybaena fruticum and find more Arianta arbustorums. After rain I could go to see if I find some more these mutant shelled ones.

[cepealove]

Jelous. I want to find a king nemoralis and attempt this project. X

[crossless]

"His" Shell is 2cm long and that cone shape is about 2,4cm high. He weigh around 4grams to 4,5grams. His really lovely. Today I'll start that project so that I set other species free where I found them and try to find more these scalariform shells

[fabrizio]

That really sounds great, Crossless!!

As for me I couldn't but strongly encourage you to carry on your project!

_Although your striking Arianta arbustorum is not "properly" scalariform, he sports anyhow another, loosely related, morhological deviation, having his penultimate whorl enlarged and bulging (that making it to detach a bit from the adjacent two whorls).

-I would say, it is a "start" morphological change towards "pupimorph" shell, that is, a shell more or less shaped as a insect (fly) pupa, more enlaged at the middle.

There are lots of species, with such shell: think of (local) Pupillidae, Enidae, Vertiginidae, Chondrinidae... even most of the Clausilidae, although much more slender.

-Tropical Amphidromus too, have a "middle enlarged" shell... although most related genera, in the same Family ( Camenidae ), have a "normal" Helix-type shell.

That teaches us, occasional mutations in shape could lead, even within the very same lineage, to entirely different and characteristic shell-types.
Most of them are negatively selected by actual environment they happen to appear within, while others are likely to be ruled out by competitive, sexual selection (partner choice).
When such initial hindrances happen to be overcome, there a "new" shell shape (and perhaps a "new species") will arise.

By means of selection, we can make good of all of such "natural" hindrances, and see some "results" within really "human" timespans!

@ Cepaealove: it could be rather "easy" indeed, just provided we are lucky enough, in the beginning, to find such "deviant" specimens... we have to be very watchful, and some will come out for sure!

-I would suggest to debate, each one in a distinct topic, everyone of such projects, I hope some of us will start (I'm engaged in that, too).

-For each "deviant" snail, we could then debate about the degree of deviation (very good starting point to take measures as you did, Crossless ), and to decide together which available specimen is more "worthy" to be mated to it, to get the more likely interesting results.

[cepealove]

Youve seen alice my possibly luecestic nemoralis, ideally id mate a king to her. althoug realistically i would be better of sorting out a luesestic line from her off spring and breeding them to a king. . . . X

[Robert Nordsieck]

I think, Arianta arbustorum also is rather polymorph, different shell types existing in different altitudes, for example.

The only thing I was able to find out was that according to Geyer (1927) a scalariform shell is the consequence of a failure of the visceral sac to coil properly, which may also happen due to external causes.

So probably it is not genetic after all.

Very much different from that is the dextral/sinistral thing, which defintively IS genetic, as we know since Alfred E. Sturtevant (1923). It is, though, very difficult to raise sinistral snails, because how the snail looks like does not correspond to it's genetic configuration. You may mate two sinistral shells and there will not be one sinistral offspring... The genetic configuration of a snail concerning shell coiling only determines the coiling direction of the offspring's shells!

Kind regards
Robert

Snail Kings - Sinistral Helix Snails

[coyote]

Robert, do you think that it could be an issue of external or environmental factors cause the gene for a scalariform shell to become activated? Perhaps it is a genetic issue after all, and the gene simply does not become activated in most cases because the external or environmental triggers happen to be absent. But I'm only taking a guess on this, I haven't studied the literature.