Hi Paul,

Here is another source for Aiptasia eating nudibranchs:
http://www.saltyunderground.com/index.htm

And now for a bit of identification trivia:

The Aiptasia eaters we've all been calling Berghia verrucicornis or
just Berghia are apparently a different species entirely. Here's the
411 on the real Berghia.
Berghia verrucicornis
http://www.seaslugforum.net/factsheet.cfm?base=bergverr
They're from the eastern Atlantic - Africa and possibly Europe - and
appparently not much is known about their habits or diet.

And here's the info on the slug that we've been calling Berghia:
Aeolidiella stephanieae
http://www.seaslugforum.net/factsheet.cfm?base=aeolstep

As an aside, the Sea Slug Forum lists three different species of
Berghia and seven of Aeolidiella.

In the end, it doesn't really make a lot of difference since you still
want to ask for "Berghia" when you're in the market for an Aiptasia
eating nudi.

Taxonomically yours,

Alex