Anthony,
I appreciate you comments and I do have your "Reef Invertibrates" book. It is full of great info. I have found a web-site that sells "aptaisia eating Berghia Nudibranchs." Is is feasible that if a nudi eats aptaisia, it would also eat a hydroid? My problem my be a thing of the past, because my little nest of hydroids seems to have been eaten by a small snail of some sort. Does that make any sense?
Thanks again,
dlh