How do shelled creatures get their shape?

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blakestyger

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How do shelled creatures get their shape?
« on: 22/12/2008 16:22:43 »
This is about how exoskeletons work. It's easier to imagine how spiders work, say, that have a protein exoskeleton that could be produced by cells that have DNA sequences that code for them, but what about snails and crabs?
As I understand it their shells are not protein but calcareous - but each species has its characteristic shape that is inherited.
The question is - how does this come about? Is it a mixture of protein and calcium compounds?
I'd really like to know - thanks.

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Offline bryan

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How do shelled creatures get their shape?
« Reply #1 on: 14/01/2009 18:49:29 »
You are right. The outer covering of the mantle of the animal secretes a mixture of proteins which causes to calcium carbonate crystals to nucleate and grow into the shell.