Morphology Sperm and Storage Organs

An important aspect of turtle reproductive biology is the ability of females to store viable sperm in their oviducts for long periods of time (Gist and Jones 1989). Females of many other taxa have evolved this ability as well (Birkhead and Møller 1993). In many social insects, for example, a queen mates prior to entering the nest and then uses only this initial sperm to fertilize eggs throughout her reproductive lifetime, which may last for years and involve the production of thousands or millions of progeny (Fjerdingstad and Boomsma 1998; Page 1986). Among the vertebrates, turtles and snakes can store sperm for by far the longest periods. In species representing these two groups, reports exist of a female's continued offspring production for up to 4 and 7 years, respectively, following isolation from males (Ewing 1943; Magnusson 1979) (although the possibility of parthenogenesis was not eliminated).

Sperm storage tubules in turtles are located in the posterior portion of the albumin-secreting region of the oviduct, a position different from that of other vertebrates (Gist and Jones 1989). The widespread occurrence of such tubules in the Testudines suggests that sperm storage, either between mating and ovulation or over longer time periods (see beyond), is an important component of turtle reproductive biology (Gist and Jones 1989).