Figure 2.

Reproductive morphology and behavior of Lymnaea stagnalis. (A) General morphology of reproductive system and gamete movement. Schematic representation of the reproductive morphology. The blue dotted lines and arrows indicate the route that the snail's own sperm (autosperm) take after they are produced for storage (in the SV) and subsequently transfer to a partner. The red dotted lines and arrows indicate the fate of received sperm (allosperm) within the female tract. All the organs are indicated with capital letters. The different components of the egg mass are indicated in small letters, and their origin is indicated with an black arrow. The red solid lines indicate the course of the eggs during packaging in the female tract. AD, allosperm duct; AG, albumen gland; BC, bursa copulatrix; C, carrefour/fertilization pouch; fert., fertilization; HD, hermaphroditic duct; M, muciparous gland; me, membrana externa; mi, membrana interna; o, oocyte; O, oothecal gland; OT, ovotestis; P, penis; PCO, pars contorta; PE, preputium; pf, perivitellin fluid; PG, prostate gland; SD, sperm duct; sf, seminal fluid; SV, seminal vesicles; tc, tunica capsulis; ti, tunica interna; V, vaginal duct; VD, vas deferens. (B) Copulation behavior. The drawings show the different stages of male courtship and insemination behavior. Copulation starts with mounting (1) on the shell. For some 5 min, the sperm donor then performs counterclockwise circling (2), first toward the shell's tip and then toward its margin. It then takes on average 17 min from positioning (3) to intromission (4), during which eversion of and probing (5) with the preputium occur. Once intromission (6) is reached, an average insemination takes 35 min. The sperm donor is displayed in black, the sperm recipient in gray. (C) Egg-laying behavior. The drawings show the different stages of female reproductive behavior, i.e., egg laying. The behavior is redrawn from Ter Maat et al. (1987). Egg laying starts with a resting phase (1) of on average 40 min, during which locomotion stops, the shell is held still and slightly pulled forward over the tentacles and no rasping occurs. During the turning phase (2), lasting around 60 min, locomoting starts again, the shell is turned back and forth by 90° and the surface is rasped. Oviposition (3) usually lasts about 10 min during which the animal continues rasping, but stops shell turning and hardly moves. During inspection (4) the animal crawls along the mass for up to 30 min without rasping or shell turning. The panels are adapted from Jarne et al. (2010).