Sensor

A bat using sonar to locate its prey.

An insect ear. The tympanic membrane, visible in this SEM of a cricket′s front leg, vibrates in response to sound waves. The vibrations stimulate mechanoreceptors attached to the inside of the tympanic membrane.

The lateral line system in a fish. Water flowing through the system bends hair cells. The hair cells transduce the energy into receptor potentials, triggering action potentials that are conveyed to the brain. The lateral line system enables a fish to monitor water currents, pressure waves produced by moving objects, and low–frequency sounds conducted through the water.