Sea shell/snail shell spirals

[burnhal]

We bought a bag of seashells for our grandaughter- obviously imports as they are larger and of differing varieties. All the spiral types- various conches, winkle type, whelk type- have a clockwise spiral going away from you if you view from the pointy end. Sadly I went into the garden and checked out the local snail population. They are the same. So the question is do all spiral molluscs twist the same way? Anyone in the southern hemisphere here? Do they twist the opposite way?

[bimbo123456]

http://findarticles.com/p/articles/mi_m1200/is _16_164/ai_110459320 shells go both ways apparently!!

[Clanad]

Interesting question, burnhal... The spiral's direction appears to be, as in other cases, such as the pine cone and many examples of plant life, logarithmic in nature and is yet another example of the Golden Ratio as it relates to Fibonacci numbers.
Although the spiral pattern can be shown to be the results of Fibonacci numbers, it appears that the direction of the initial 1-1 is genetically controlled. Several web sites indicate that the spiral direction is no different in the Southern Hemisphere than in the Northern. Here's a site you may find interesting:

http://www.mcs.surrey.ac.uk/Personal/R.Knott/F ibonacci/fibnat.html#spiral

Thanks for an insightful question!

[burnhal]

Thanks all!
Talking of spirals and fibbonachi numbers reminds me of the romanesque cauliflower. I had never seen one til they appeared in our local supermarket last year. It is bequtiful. All the florets are in spirals. Each floret has its own individual spirals on it and if you peer closely at the individual parts of the florets they again have there own spirals. It was almost a shame to cut it up and eat it!