Thanks for the reply. Amongst the 1000+ cuttlefish on that location for 15 days , it was the only ones involved in such a cannibalistic behavior. What surprises me is that they don't seem to be interested in eating during the mating season... and that they will die anyway in few weeks time. But... as some males are much much larger that other ones, I am wondering if, like some Atlantic salmon, some are living longer than other ones, and return to the feeding grounds after mating. Any ideas ?