THE OLFACTORY ORGAN OF THE HARDHEAD SEA CATFISH, ARIUS-FELIS (L) - GROSS MORPHOLOGY AND FINE-STRUCTURE

The olfactory organ of the hardhead sea catfish, Arius felis (L.), was investigated morphologically by means of light and electron microscopy (SEM, TEM). The two rather large nostrils of each side lie close together, surrounded by upstanding margins. The olfactory rosette consists of a midline raphe with two rows of lamellae. The sensory epithelium on the lamellae is almost continuous and contains receptor cells of both the ciliated and the microvillous type. Ciliated non-sensory cells are scattered throughout the sensory epithelium. Accessory ventilation sacs are lacking. The shape, position and size of the nostrils indicate that forward motion of the fish creates the water current through the olfactory organ (kolymbosmates). The scattered nonsensory cilia may aid in ventilation. The olfactory organ of A. felis differs from that of the other marine catfish, Plotosus lineatus, and from those of freshwater catfishes. The morphological differences are discussed with respect to species-specific behavioural activities.