The spiracular organ of sharks and skates: anatomical evidence indicating a mechanoreceptive role.

The elasmobranch spiracular organ is a specialized receptor associated with the first visceral pouch. The structure of the sensory epithelium of the spiracular organ and the pattern of central termination of the afferent neurons that innervate it show that the spiracular organ is a mechanoreceptor closely related to the lateral line system of sense organs. Its position and orientation within the spiracular cleft suggest that it plays a role in proprioception or equilibrium-audition.