Amphibia respiratory system arrangement is which?

• A. Gills (juvenile), Lungs (adult)
• B. Lungs only
• C. Gills only
• D. Skin diffusion only

Answer: (A)

Amphibians show a life-stage shift in respiration. In the aquatic juvenile stage, they typically rely on gills to extract oxygen from water, which is paired with a moist skin that can also contribute to gas exchange. As they metamorphose into adults, lungs become the primary organs for breathing air, and they ventilate them using buccal pumping and thoracic movements. While the skin remains a route for gas exchange when moist, the major shift from gills to lungs across development makes the pattern of gills in the juvenile stage and lungs in the adult stage the best description. This explains why larvae breathe with gills and adults with lungs, rather than lungs-only, gills-only, or skin diffusion-only as the primary arrangement.