|Shedding of the penis in Littorina littorea|In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836, more
Littorina littorea (Linnaeus, 1758) [WoRMS]; Marine
Seasonal resorption of the penis accompanying regression of the testis has been recorded in some dioecious Proso-branch gastropods. Nassarius obsoletus is said to resorb the penis at the end of the breeding season and regenerate it almost immediately; a similar phenomenon has been described in the periwinkle Littorina littorea: the penis is said to become reduced in August and September, perhaps disappearing altogether. This reduction has been described histologically. Reduction of the penis in L. littorea during the summer is a well established phenomenon in current literature. In L. saxatilis the penis, testes and seminal vesicles have been reported to be much reduced in size during the summer. In L. obtusata, however, which breeds all the year round, the penis seems to remain constant in size after sexual maturity is reached (ref. 3 and personal communication from D. Guiterman). Tills is also the case ID the Hawaiian species L. pintado and L. picta, where breeding is again continuous.