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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: sci.chem,sci.bio
Subject: Re: What is tortoise shell made of?
Summary: Perhaps chitin...
Message-ID: <3984@kitty.UUCP>
Date: 30 Aug 90 03:09:00 GMT
References: <1990Aug29.133624.8472@cunixf.cc.columbia.edu>
Organization: Recognition Research Corp., Clarence, NY
Lines: 29

In article <1990Aug29.133624.8472@cunixf.cc.columbia.edu>, shenkin@cunixf.cc.columbia.edu (Peter S. Shenkin) writes:
> Is it alpha chitin, or something else?

	The exoskeleton of lobsters, snails and other crustaceans is formed
of chitin (a polysaccharide and linear polymer of N-acetyl-d-glucosamine)
impregnated with calcium carbonate.  It seems to me that the same material
may constitute tortoise shells, but I do not know for certain.  One factor
which makes me believe this is that tortoise shell can be formed and fused
using heat and pressure - not true of "traditional" bone.

> Are the top and bottom shells made of different things?

	They certainly look different (the top is called the carapace, but
I don't recall the name for the bottom), although I suspect there may be
some similarity in composition.

> Which used to be used for combs and so on?

	The traditional tortoise shell material was obtained from only one
species of tortoise.  The carapace on this species has various removable
"shields" - this was the primary source for the tortoise shell material,
and not the carapace proper.

	I suspect that today, natural tortoise shell combs are about as
popular as whale oil. :-)

Larry Lippman @ Recognition Research Corp.  "Have you hugged your cat today?"
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