Which organ do mollusks use for gas exchange with water?

Which organ do mollusks use for gas exchange with water?

• A. Gills
• B. Mantle
• C. Foot
• D. Radula

Answer: (A)

Gas exchange in aquatic mollusks happens mainly through gills, also called ctenidia. These delicate, highly vascularized membranes sit in the mantle cavity and are exposed to water as it flows over them. Oxygen diffuses from the water into the blood, and carbon dioxide diffuses out, often with a highly efficient countercurrent arrangement that maximizes oxygen uptake. The mantle’s job is broader in many mollusks, mainly forming the shell and housing the gills, while the foot and radula serve locomotion and feeding roles, respectively. In some land-dwelling mollusks the mantle cavity can function like a lung, but for life in water, gills are the respiratory organ.

Gas exchange in aquatic mollusks happens mainly through gills, also called ctenidia. These delicate, highly vascularized membranes sit in the mantle cavity and are exposed to water as it flows over them. Oxygen diffuses from the water into the blood, and carbon dioxide diffuses out, often with a highly efficient countercurrent arrangement that maximizes oxygen uptake. The mantle’s job is broader in many mollusks, mainly forming the shell and housing the gills, while the foot and radula serve locomotion and feeding roles, respectively. In some land-dwelling mollusks the mantle cavity can function like a lung, but for life in water, gills are the respiratory organ.