A. aculeatus is a diurnal species that lives on very shallow reef flats. As such, they experience bright, broad spectrum light. The ones that we keep in the lab don't seem to mind bright ambient lighting.
We have a juvenile A. aculeatus right now that lives in a cavity in a small rock. Usually all I can see is his eye looking out of a 1 cm hole and much of the time he keeps that hole closed with a small rock or shell. However, when he gets hungrey, we see his head bobbing up and down from behind the rock and when he is really hungry, he comes out and paces back and forth on the glass. As soon as he is fed, he takes the food back to the rock and we don't see him for another day or two. This behavior is very different from what we have seen in mature adults and I'll be curious to see if he becomes less cavity oriented as he matures.
Roy