"Has genetic work been done to try and determine how long these populations have been "isolated" from their more shallow-water counterparts?" Ross, I don't know how long exactly vent populations are separated from their shallow water relatives,but there was made some mollecular research which suggests that at least one vent group -Neomphalid gastropods- represents long-term in situ evolution. Best regards, Milan ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com