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Arachnids

Does anyone know how many orders there are? Our site says 12 from (1).

arachnology.org says there are 11 here.

One of my books says 17 The Encyclopedia of Animals a complete visual guide.

Wait, I think I've answered my own question.....one reference states there are "about" 11 orders alive today. See this site.

Then this site says there are 12 living orders and 5 extinct see this site.

SO, is it 12 or 11 living orders???

Thanks,
Contributed by Lynette Elliott on 13 November, 2005 - 7:38am

Still in question?
It appears to be twelve living, five extinct, as you noted. Arachnology.org does not mention the twelth living order, (previously noted, but different yet interesting link) for some reason.

Except for the one site, the numbers add up.
… Jeff Hollenbeck, 13 February, 2006 - 6:41pm

 
Horseshoe Crabs
Horseshoe crabs have traditionally been considered at closest a sister taxon to the Arachnida during the entire history of the discipline of arachnology, so I can understand a bit of reluctance to change the very identity of their profession on the strength of a few phylogenetic studies.

The science of molecular genetics as applied to taxonomy is still fairly new and incomplete- taxonomy is in a tremendous state of flux. The state of the art today may be seen in 20 years as a quaint and short-lived fad. Perhaps they're waiting for the dust to settle before making big changes.
… Chuck Entz, 13 February, 2006 - 10:35pm

 
Thanks,
It was still in question, but I had forgotten I asked it :).
… Lynette Elliott, 13 February, 2006 - 7:44pm

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