b9 wrote:
insects have to breathe and they have a tracheal system that is in contact with the outside world that infuses oxygen via tracheoles to their "blood" stream, so why does bacteria not use it as a portal for infection and subsequent instillation of putrefaction?
This is true, and putrefaction must occur - but the soft tissues are of such small quantities that they appear to "dry up" more than "putrefy" (as compared, say, to a rabbit carcass which would have a much more significant putrefaction cycle).
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why does not the internal bacteria that is suppressed by the living insects immune system not suddenly flourish when they die like they do in all other forms of life?
They quite probably do but again, because of the tiny amount of matter available for decay the effects would barely be visible without some close, long-term study of the event, and I suspect the Chitin parts remain largely unaffected because the bacterial activity simply doesn't last long enough.
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i know that insects become dessicated due to evaporation of their hydrated tissues when they die, and that their weight after a long time is the weight of the matter of their bodies minus the water, but why do they not become consumed totally
Given time, the breakdown must become total. Even man-made plastics break down eventually but the time this takes depends on the chemical make-up. So, for example, a plate of iron will
eventually crumble completely if left exposed to air.
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i guess if i had a dead fly in a bottle for 500 years, that there would inevitably come a time when gravity exceeds the bonds of the completely dehydrated and feeble tissues of the insects exoskeletal joint bonding integrity, so that some part falls off like the head, and then the outside world has ingress to the internal spaces within the insect, and with it's humidity, will hydrate and make digestible, the exoskeleton.
The head and other parts would have been held in place by the insect equivalent of muscles - or at the least, something containing much less Chitin than a hard shell so that they would remain flexible - and so various bit would eventually start dropping off. Even a hard shell is only an arrangement of Chitin plates and that too would eventually fall apart into its individual plates.
I don't think the ingress of air that this process allows would make too much difference overall though, because it seems to be in the nature of Chitin (and Keratin) that it is chemically very stable and like the iron plate, it just takes
much longer to decompose. Of course the presence of water is likely to accelerate this process in both cases but with Chitin, it's evidently much less susceptible to the effects of this than the soft tissues. Some insect collections are over 100 years old but the Chitin is
still intact.
There are interesting Wikipedia pages for Keratin
here and Chitin
here.
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thanks for your answer.
Small details are
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but of course this post will slide under the rolling sands of random contemplation in the tidal face of thousands of people who want to say random things.
"All things pass".
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Giraffe: a ruminant with a view.