I've pondered that myself. Our own Brandon Hill of
Zoanthids.com in Orem did a meeting presentation a few years ago where he discussed that and all kinds of other good stuff about these amazing polyps. He even spoke of a distinction between Mini-zoanthids regular Zoas, Palys and Palythoa Grandis. It was something about number of tentacles or size or mouth shape, etc.. I couldn't find anything posted here after his presentation, though I believe he offered to share it with us. Maybe your personal request via the website will generate a response.
That reminds me. I'm farming a particular Paly(?) that acts like an aggressive anemone. When I touch it with my finger the tentacles grab and the frag hangs on when I lift my finger. Every other button polyp I've ever had always retracts at my touch.
Aloha,
Mark
