Which structure on a fish senses vibrations in the water?

• A. Pharynx
• B. Gills
• C. Lateral line
• D. Swim bladder

Answer: (C)

Detecting vibrations and water movement is handled by the lateral line, a specialized sensory system that runs along the sides and head of a fish. It contains neuromasts, which are cells that respond to changes in water flow and pressure caused by nearby objects, prey, predators, or moving shoals. This information lets the fish sense obstacles, coordinate schooling, hunt effectively, and navigate in low-visibility water. The pharynx is part of the throat involved in swallowing and feeding, not sensing vibrations. The gills handle gas exchange, pulling oxygen from water and releasing carbon dioxide. The swim bladder regulates buoyancy and depth, not direct vibration sensing. So, the structure that senses vibrations in the water is the lateral line.