An autoradiographic study of sperm exchange and storage in a sea hare, Phyllaplysia taylori, a hermaphroditic gastropod (Opisthobranchia: Anaspidea)

Abstract

Tritiated thymidine autoradiography was used to distinguish exogenous from endogenous sperm and to determine the translocations of labeled sperm within the simultaneously hermaphroditic, reciprocally copulating gastropod Phyllaplysia taylori. Heavily labeled sperm start leaving the ovotestis within 14 days after injection of H3‐thymidine. These endogenous sperm are stored, evidently less than 20 days, in the ampulla prior to copulation. During copulation the endogenous sperm are tightly bound to one another by extracellular material forming a seminal strand. This seminal strand is moved by ciliary action along the spermoviduct fold and genital groove to the tip of the extended penis. As the seminal strand issues from the tip of the labeled animal's penis into the copulatory duct of an unlabeled mate, the extracellular material of the strand dissolves, releasing the now exogenous sperm (some of which are labeled). Most of the labeled exogenous sperm are found in the seminal receptacle within two hours after copulation. Within five hours some of these sperm have become oriented with their heads buried into the receptacle lining. Surplus exogenous sperm flow into the copulatory bursa where they are destroyed.

Sexual Conflict in Hermaphrodites

“…There is thus likely to be a strong incentive for the sperm recipients to control the fate of received substances, and one possible solution is to evolve means of sperm (ejaculate) digestion. There can be no doubt that significant sperm digestion occurs, with well-developed sperm-digesting organs described for example in gastropods (Beeman 1970;Brandriff and Beeman 1973;Beeman 1977;Beese et al 2006), flatworms (Sluys 1989), and oligochaetes (Westheide 1999). Similarly, even in species with traumatic insemination (see below) that lack specific sperm receiving organs, received sperm appear to be rapidly cleared from recipients (e.g., Macrostomum hystrix; S Ramm, A Schlatter, M Poirier, and L Schärer, unpubl.).…”

Sperm movement and morphology in a simultaneous hermaphroditic sea slug

“…Alternatively, glycogen helix serves to maintain sperm viability during longterm storage. Sperm of hermaphroditic gastropods (Opisthobranchia: Anaspidea) are stored less than 20 days (Beeman, 1970), implying that some energy sort is required during storage However, further study is required to confirm these presumptive roles of the flagellum.…”

Mating Behaviour of the Sperm Trading Sea Slug Chelidonura hirundinina: Repeated Sex Role Alternation Balances Reciprocity

“…Some of the received allosperm are stored in the receptaculum seminis prior to fertilization (Rudman 1974; Klussmann‐Kolb 2001). The remaining sperm are digested in the gametolytic bursa copulatrix (Beeman 1970; Baur 1998). Male and female copulatory organs are anatomically separated (Fig.…”