MORPHOMETRIC VARIATION OF DIFFERENT PARAMETERS OF SNAIL Segmentina trocoidea, VECTOR OF Fasciolopsis buski, IN DIFFERENT SEASONS IN A PERENNIAL AQUATIC BODY AT MOURIGRAM, HOWRAH, WEST BENGAL, INDIA.

In bioecology as well as evolutionary biology the morphometric measurement of shell of various gastropod snails is very interesting job in malacology.There are various methods in this aspect. Although there are various reports in morphometry in different Polmonate mollusca but in Segmentina trocoidea there is no report. As it is very tiny mollusks it is very difficult to study. It pays importance as it is a vector snail of Fasciolopsis buski. The shell diameter, shell height, total body weight and empty shell weight were measured to establish the relation between them. The seasonal variation also plays important role in morphometric variation. The final and total result of the population collected from Mourigram aquatic body shows that the average diameter of 16,445 snail in three year is 2.198787 ±0.64mm ,average height is 1.649135 ± .65mg and average total weight is 2.454201 ± .05mg and the dry weight of empty shell is 0.695371 ±.067mg. The winter size group shows maximum diameter, maximum weight and maximum shell weight where as the summer size is medium and the rainy season size group is the minimum.