shenkin@cunixf.cc.columbia.edu (Peter S. Shenkin) (08/29/90)
Is it alpha chitin, or something else? Are the top and bottom shells made of different things? Which used to be used for combs and so on? -P. ************************f*u*cn*rd*ths*u*cn*gt*a*gd*jb************************** Peter S. Shenkin, Department of Chemistry, Barnard College, New York, NY 10027 (212)854-1418 shenkin@cunixc.cc.columbia.edu(Internet) shenkin@cunixc(Bitnet) ***"In scenic New York... where the third world is only a subway ride away."***
larry@kitty.UUCP (Larry Lippman) (08/30/90)
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?" VOICE: 716/688-1231 {boulder, rutgers, watmath}!ub!kitty!larry FAX: 716/741-9635 {utzoo, uunet}!/ \aerion!larry
shenkin@cunixf.cc.columbia.edu (Peter S. Shenkin) (08/30/90)
In article <3984@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: >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... I just asked a biologist, and got the following answer. The shell is made of something called dermal bone, a primitive sort of bone similar to our skull bones. The bone constituting the upper shell is bonded to the spine, which is a unique architecture that I suppose defines tortoises/turtles. However, the bone is covered with keretin, not chitin, as I had guessed, and it is the keretin that we see, and which was used to make combs and so on. Keretin is proteinaceous, unlike chitin, which is a carbohydrate. I suspect that, in general, vertebrates don't make chitin; the exoskeletons, of insects, as well as crustaceans, are made out of it. -P. ************************f*u*cn*rd*ths*u*cn*gt*a*gd*jb************************** Peter S. Shenkin, Department of Chemistry, Barnard College, New York, NY 10027 (212)854-1418 shenkin@cunixc.cc.columbia.edu(Internet) shenkin@cunixc(Bitnet) ***"In scenic New York... where the third world is only a subway ride away."***
JAHAYES@MIAMIU.BITNET (09/01/90)
The "bottom" of a turtle or tortoise is called the plastron. So there. Ya learn something on the net, once in a while. - - - - - - Josh Hayes, Zoology, Miami University, Oxford OH 45056 jahayes@miamiu.acs.muohio.edu or jahayes@miamiu.bitnet
shenkin@cunixf.cc.columbia.edu (Peter S. Shenkin) (09/03/90)
In article <90243.121009JAHAYES@MIAMIU.BITNET> JAHAYES@MIAMIU.BITNET writes: >The "bottom" of a turtle or tortoise is called the plastron. And I believe the top is called the "carapace." -P. ************************f*u*cn*rd*ths*u*cn*gt*a*gd*jb************************** Peter S. Shenkin, Department of Chemistry, Barnard College, New York, NY 10027 (212)854-1418 shenkin@cunixc.cc.columbia.edu(Internet) shenkin@cunixc(Bitnet) ***"In scenic New York... where the third world is only a subway ride away."***