Abstract: Carbohydrate and polysaccharide contents in Arion ater are highly dependent on stageof the life cycle (male (August) or female (November)), type of carbohydrate in the food (starchyor non-starchy foods) and tissue (body wall (BW) or genitalia (G)). Carbohydrates accounted fornearly a 37.3% of the dry weight (DW) of body walls of male slugs fed in the lab for 10 days onstarchy foods, whereas that content lowered to 21.5% of DW of BW of female slugs. When slugswere fed for the same period on foods lacking starch, carbohydrate content (CC) of BW loweredto 13.6% of DW in male slugs and dropped to 6.9% of DW in females. Regarding genitalia, CCof reproductive tissues in female slugs was 42.0% of DW when slugs were fed on starchy foods,and a mere 27.8% of DW when fed on or non-starchy foods. Most of the carbohydrates seem tobe polymerized, because polysaccharides stand for ≈57% of the carbohydrates in BW of bothmale and female slugs fed on starchy foods. When slugs were fed on non-starchy foods,polysaccharide percentage reduced to 42.3% of the carbohydrates in males and, as it could beexpected, diminished more in females, where polysaccharides represented only a 30.6% of thecarbohydrates. In genitalia of female slugs the carbohydrates were primarily in their polymerizedform, but their percentages did not depend on the amount or on the type of carbohydrate presentin food.