Anatomy of finfish and shellfish

Unit 11 - Sensory System in fishes

11.2. Nares
One or two nares (nostrils) on each side of the snout leading to a build sac represent the organs of smell externally among fishes. However, in the lampreys and hag fishes the nostril is single and median. Most fishes have the narial openings at the top and sides of the snout. In other such as the sharks, rays and skates the nares are on ventral surface of the snout. In dog sharks, the narial apertures by a flap of tissue into incurrent and excurrent pores to complete separation of incoming and outgoing water through development of a separate pore for each current, in most teleost there is often value for classification in the fleshy valuular tissue of the teleosts. In living lungfishes (Dipnoi) the external incurrent nares communicate by passage with excurrent nares that have come to lie in the mouth cavity.