La maturation sexuelle chez les mâles d'Octopus vulgaris (Cephalopoda: Octopoda), en relation avec le réflexe photo-sexuel

The role of light in induction of sexual maturation in male Octopus vulgaris has been studied on experimentals reared in the laboratory. Experiments were carried out during January, February and March, the time of the year when females do not breed or are just beginning to breed. Males (20 to 500 g) were artificially illuminated for 8 or 16 h/day or kept in complete darkness. Their gonads were compared with those of wild specimens killed a few hours after capture. In the Mediterranean Sea, under natural conditions, O. vulgaris males of less than 150 g never display sexual maturity; under our experimental conditions, young males from 70 g onwards, illuminated 16 h daily, show gonad development. Males of over 150 g, illuminated 16 h daily, have a larger number of spermatophores than wild specimens of individuals illuminated 8 h daily. O. vulgaris reared in complete darkness are sexually more mature than wild individuals. An hypothesis on induction of sexual maturation in the Cephalopoda is proposed.