Which organ allows sharks to hear vibrations throughout their body?

• A. Inner ear
• B. Lateral line organ
• C. Cochlea
• D. Semicircular canals

Answer: (B)

The ability to sense hydrodynamic vibrations across the body is what lets sharks detect movement in the water. The lateral line organ runs along the sides and through the head and contains sensory units called neuromasts in fluid-filled canals. When water is disturbed by prey, predators, or currents, pressure changes bend the hair cells in these neuromasts and send signals to the brain. This setup provides information about the direction and strength of vibrations across much of the body, giving sharks a broad sense of their surroundings even when visibility is poor.

The inner ear and its associated semicircular canals are mainly about balance and local sound perception in the head region, not about detecting vibrations across the whole body. The cochlea is a structure of the mammalian inner ear and isn’t present in sharks. So the lateral line is the mechanism that enables body-wide perception of water vibrations.