Limited use of stored energy reserves for reproduction by the tropical loliginid squid Photololigo sp.

This study sought to determine if the tropical loliginid squid Photololigo sp. stores energy ill the form of lipid, carbohydrate or protein for reprod uctive investment. Individuals were examined for changes in morphometry, ma ntle muscle structure and concentrations of water, lipid, carbohydrate and protein in muscle tissue and the digestive gland, associated with the stage of reproductive maturation. Muscle mass was affected by reproductive matur ation in females. Mature individuals were lighter for their length compared with females in the early stages of maturation. Concentrations of lipid an d carbohydrate in the muscle tissue were very low, and female Photololigo s p. showed equivocal evidence of declining lipid and carbohydrate levels wit h egg production. There was no evidence of dramatic changes in protein conc entration in the mantle muscle with reproductive maturation. Male Photololi go sp. showed a change in the digestive gland with maturation, with water c ontent increasing and protein concentrations decreasing. The digestive glan d of both male and female Photololigo sp. increased in size and contained l ess water with growth. There was little evidence that the storage and trans fer of energy for reproduction occurred in Photololigo sp. Instead, it is p robable that energy for reproduction is predominantly sourced directly from consumed food.