Morphological investigation of the pharynx structure of Ascidiella aspersa (Muller, 1776) (Ascidiacea:Tunicata) in Izmir Bay

Ascidiella aspersa (Muller, 1776) species belonging to Ascidiacea class that inhabit the polluted and clean benthic zones, were taken as an illustration to determine the effects of the upper surface of ascidians as a pollution indicator in Izmir Bay's (Turkey) pollution. The pharynx and gill grows called stigmata that are located on pharynx, have been compared morphologically in clear and polluted zone samples. With respect to the adaptations which increase the surface area, they are assigned to minimize the pollution effects in pharynx structure of polluted zone samples.