[Taxacom] Tardigrades ----> to Nematodes
Michael.Reuscher at gmx.net
Tue Feb 16 11:42:42 CST 2010
Wow, sounds fascinating. I am only wondering if this is based on science or a fanciful mind. How did the tardigrades acquire the moss gene ?
> Dear All,
> Isn't it interesting that tardigrades and nematodes are among the
> few animals able to enter cryptobiosis, especially when threatened by
> extreme desiccation. I would suggest that some clade of tardigrades
> acquired genes for the production of trehalose sugars from primitive
> land plants (such as mosses). Both groups would have faced the same
> problem of desiccation as they invaded land environments during the
> early Paleozoic.
> I propose that tardigrades in turn passed these "trehalose genes"
> on to their nematode descendants, thus enabling them to also take
> advantage of cryptobiosis as a survival strategy. Something to look for
> when comparing nematode and tardigrade genomes.
> --------Ken Kinman
> P.S. If tardigrades evolved from arthropods, as I suspect, did they
> evolve from crustaceans or from chelicerates??? Both of these arthropod
> groups give rise to terrestrial forms with reduced number of legs.
> Modern tardigrades have four pairs of legs like many arachnids, but the
> known fossil tardigrades from the Cambrian of Siberia were apparently
> hexapodous. But then again, I suspect hexapody may have arisen
> independently more than once from crustaceans. Therefore, the exact
> number of legs may not be definitive, except that perhaps reduction to 3
> or 4 pairs of legs may somehow be particularly advantageous on land
> given the high diversity of hexapods and arachnids on land.
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