 " Male @-@ parallel " mating involves the male and female swimming side by side . The male will then raise one or two of his arm pair I upwards and swing them back and forth . He moves below the female and clasps the female 's neck with his arms . In contrast to the previous behaviours , in this position the male actually inserts his <unk> into the mantle cavity of the female , attaching the spermatophores right at the opening of the oviduct rather than at the mouth . Possibly for this reason , it is usually more successful in fertilizing the female than other mating behaviours . 
