What do echinoderms lack?
Options:
- (A) Lungs
- (B) Mass
- (C) oxygen
- (D) eardrum
- (E) gills
- (F) ovaries
- (G) Organs
- (H) Bodies Think carefully first, then make a decision. My thoughts:
Echinoderms lack respiratory and excretory systems. Lung mechanics and gas exchange are topics during study of the respiratory system. Echinoderms have no lungs. So the answer is (A).