Pteraeolidia ianthina is a sea slug in the family Aeolidina and as such closely related to Phyllodesmium. Like Phyllodesmium adult specimens of P. ianthina can incorporate and utilize zooxanthellae from cnidarians thus gaining the ability to cover a great part of their food requirements by photosynthesis, the rest being covered mainly by feeding on the large solitary hydroid polyp Ralpharia sp.
Juvenile animals don't seem to have the ability to photosynthesize and thus appear white with the characteristic purple striped oral tentacles. They usually feed on smaller hydroids.
Keeping P. ianthina in an aquarium might actually be successful for quite some time since a large part of their energy needs are covered by illumination - in the long run, however, the lack of suitable hydroids will in all likelihood lead to the starvation of the animal.