HI there! I would like to ask... Why do some tarantulas (ref. Theraphosidae: Tarantulas) thrive in a dry, arid environment, yet diminish in a high humid environment?, and also if I can reverse that question to Why do some tarantulas thrive in high humidity environment, yet diminsh in a dry, arid environment? What characteristics define this conditioning?
When I compare entomology types from the written literature available (book publications, Aracnoboards, BTS, ATS and the British Museum), regarding the biology of tarantulas I can't seem to pin point the answer. I've read quite a bit to ensure my pets are in the best possible habitats, but this bit of information seems to elude me. Or rather, it's there and I don't understand it. Scientific papers can sometimes have so many references that it can get quite confusing for the non-scientist!
If I could use the species Brachypelma smithi vs. Hystereocrates gigas, (very dry vs. very damp/humid) or Grammastola porteri vs. Orphnaecus sp. (dry vs. humid) as an example of my thinking, each a different genus, each with a different level of tolerance to water and humidity, and also geographically placed..what biological difference makes each tarantula need more water/humidity than than other?
An clear answer, or least a nod in the right direction for that clear answer would be most appreciated.

regards
Stuart

sorry but no-one seems to know the answer to your question.