In a specimen-based viva, the examiner describes this case: a sea star exchanges gases through small skin gills and the surface of tube feet. Choose the concept that fits it best.

Sea stars use dermal branchiae and tube feet for gas exchange. Their thin surfaces allow diffusion between seawater and body fluids. This MCQ belongs to the Echinodermata topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.