mpenders wrote: The anemones are also gone in the 2nd pic. Would they have been feasting on the sponge - and would they also be on the menu of the dorid?
Greetings,
1. Anemones eating sponge - Almost certainly not; anemones simply aren't mobile enough and seem to lack the ability to sense prey over any distance - making it almost infinitely unlikely that an anemone species would evolve to prey on sponges. The anemones pictured appear to be juvenile
Epiactis spp. which, like most of our local anemones, mainly eat various small crustaceans (copepods, amphipods, etc.).
2. Dorid nudibranch eating anemones - Highly unlikely; dorids, as a group, are considered to be extremely specialized as to diet, in some cases they are obligate predators on one prey species. Many (most?) dorids eat sponges and if you see one doing so there's a pretty good chance that the animal in question
can't eat anything else. If I guessed correctly about the anemones pictured, they had probably fairly recently left their parent's column and were seeking out a suitable place to live on their own and the sponge was simply in their path; further, given that sponges are often somewhat toxic I would speculate that the anemones would have wanted to get off of them ASAP. Alternatively, it's possible that the dorid could have 'bulldozed' them out of the way as it was consuming the sponge.
Having said that:
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy.
- Hamlet (1.5.167-8), Hamlet to Horatio
In other words, I could be all wet here.
Predatorily yours,
Alex