ROTFL
You guys are truly funny.
I lost my train of thought, I've been busy all day trying to teach Helen how to whistle.
>you are saying that they must use these 3 nutritional pathways in order to exist in the long term?<
In the wild.
>Or are you saying that they have evolved to have them because their nutritional requirements cannot be met by one on a consistent basis? Or none of the above?<
Yes, and it takes a combination of all.
Or that the ones that had this ability were able to have better survival rates and colonize more areas.
They have survived by being able to take advantage of whatever nature throws at them (or doesn't throw at them). This is more or less a sessile animal that doesn't have the short term option of actively hunting. It's more of a wait in ambush approach. Hoping that they picked a good spot. Even with that, spots change
. What might be a good spot right now, might not be all the time (seasonal). They have the option of moving, but moving carries it's own risks.
So they have a couple of backups that work when prey is not available. If they were able to sustain themselves on prey along, then the need for zoox and absorption pathways would have been un-chosen traits. The energy and location specifics associated with maintaining these other two traits are too site/host dependent. In other words, they are too limiting to the animal. From this you can deduce why these anemones are not found in deeper, darker waters where more prey is available. They have evolved to fill a niche in the clear waters of the upper reef. Sitting right out in the open. Not even under a overhang or in a cave, where it would be more likely for prey to blunder into them.
They are much better adapted to their own nutritional needs than a lot of the non-photo anemones. Considering their great size and high metabolisms.
Jerel