Andrew and Frank et al, Look at the cichlids (fish)of Lake Victoria(?) in Africa. Introduction of new species by people made the water cloudy and prevented closely related species from distinguishing each other (they were dependant on color patterns). Now there are fewer, blander species. Not sure if this is at all applicable to marine mollusks which probably use chemical cues to distinguish species, but at the rate we are spreading pollutants into the environment, we may eventually screw them up too. Allen Aigen [log in to unmask] ---------------------------------------------------------------------- [log in to unmask] - a forum for informal discussions on molluscs To leave this list, click on the following web link: http://listserv.uga.edu/cgi-bin/wa?SUBED1=conch-l&A=1 Type your email address and name in the appropriate box and click leave the list. ----------------------------------------------------------------------