 Opisthobranch gastropods are hermaphrodites , as are the pulmonates , however opisthobranchs do not have love darts . Nonetheless , some of them do stab one another during mating , using hardened anatomical structures . For example , in the Cephalaspidean genus Siphopteron , both seaslugs attempt to stab their partner with a two @-@ part , spined penis . 
