Just did a little more research... It appears that feeding each polyp is highly recommended. Polyps that are not regularly fed will whither and die. The reason that they are usually found in entrances to caves has nothing to do with liking or not liking light, but has to do with the amount of food available.
These corals have an extreme appetite, and benefit from frequent feedings, anywhere from 2 times daily to twice a week. The more they are fed the quicker they grow.
Sorry for the previous information, I did not see the article that I mentioned above.
Kelly