QUANTITATIVE DIFFERENCES IN THE CHEMORECEPTOR SYSTEMS IN THE BARBELS OF 2 SPECIES OF MULLIDAE (MULLUS-SURMULETUS AND M-BARBATUS) WITH DIFFERENT BOTTOM HABITATS

Qualitative and quantitative observations were made of the growth, dis tribution and density of external taste buds (TB) in the barbels of 2 phylogenetically close species of the Mullidae family (Perciformes: Te leostei] from the NW Mediterranean. Both species live on the continent al shelf and have similar benthivorous feeding habits, but each prefer s a different bottom habitat. Mullus surmuletus is typical of sandy an d rocky bottoms, while Mullus barbatus is found over muddy bottoms and reaches to deeper waters than M. surmuletus. The barbels of M. barbat us differ from those of M. surmuletus in that they have a greater dens ity and number of TBs, which are characteristically distributed in wel l-defined groups. These characteristics of M. barbatus are associated with a greater sensitivity to chemical stimuli, as there is a compensa tory relationship with the reduction of the visual field which occurs in muddy and deeper waters.