Antennae vary greatly among beetles. Many beetles have antennae made up of thread-like or bead-like segments. In many of these beetles, the tip segments of the antennae are club-shaped. Some beetles have elbow-shaped or feather-like antennae. A beetle's antennae are covered with hairs and special organs that can detect specific odours. Some beetles have special sense organs near the base of the antennae that provide a simple type of hearing. These organs send messages to the brain when certain sounds vibrate the antennae.