chirality of snail shells and survival

[monty]

This BBC article (and probably the underlying paper, which I haven't dug up yet) are probably of interest to some of you, even though it's not directly ceph-related... wasn't sure if here or "fossils and history" is the best place for it, since non-planar shells aren't found on any living cephs (maybe argonauta?)...

http://news.bbc.co.uk/2/hi/science/nature/4831218.stm

 

[Euprymna]

Yeah, very interesting indeed!
My initial thoughts when reading was obviously that if these left handed shells were immune to crab predation, the whelk population would slowly shift towards all left handed whelks but no!! why would left handed shells be less successful in finding a mate, aren't they broadcast spawners anyway? mmmm...have to dig that paper to (monty any success?)

eups

 

[main_board]

I know of some snails that have to, um, 'mount' each other (for lack of a better word, not sure what to call it with gastropods) in order to fertilize the eggs. Perhaps this is more challenging if your holes aren't on the same side of the shell. Seems to make sense. I mean snail aren't the most flexible of creatures. Very interesting article and discovery.

Cheers!

 

[Euprymna]

Yeah right, it makes sense.
However, I would still guess that IF these crabs were the only predators, in the long they would be removing the right handed individuals out of the population, hence the probability that two left handed ones meet and mate would increases and eventually lead to a population dominated by the left handed freaks.
I should read the original paper but from this article it seems that they assume the crab predation to be the only parameter putting pressure on the whelk population. Surely, there are other predators that have no problem in consuming left-handed whelks (such as shell drilling octopuses maybe?? ) and these would also affects the dynamic of the whelk population...
just a thought!

eups

 

[Fujisawas Sake]

Aye, dude, you beat me to the punch about the sinistral snails!

Wow! That's actually quite interesting. It makes for an interesting case for predator-prey interactions. Now for a satisfactory explanation on torsion....

John

 

[um...]

What's the story from a developmental point of view, I wonder? How does the sinistrality arise? Does the required aberrance in development have side effects that are selected against, either internally or externally?

 

[Fujisawas Sake]

I think it has something to do with the chemistry of shell formation, and how the respective genes are expressed in said formation. I think the "handedness" of the shell could also be affected by the "handedness" of the populations of snail predators as well.

just my

John

 

[cuttlegirl]

For someone who has a greater genetic background than me...
Speciation and Gene Flow Between Snails of Opposite Chirality by A. Davison, S. Chiba, N. Barton and B. Clarke
http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0030282#JOURNAL-PBIO-0030282-B19

What I did get from this article is that chirality develops early in the embryo and is maternally inherited.

 

[Jean]

I think it has something to do with the chemistry of shell formation, and how the respective genes are expressed in said formation. I think the "handedness" of the shell could also be affected by the "handedness" of the populations of snail predators as well.

just my

John

Although some won't care! We have a number of shell boring whelks that will bore through the shell whereever on another gastropod (they're more discriminating on bivalves and bore at the adductor muscle!) and our wrasses eat the gastros shell and all!!!

J