A comparison of sperm morphologies, transfer and sperm mass storage between two species of crab,Ovalipes ocellatusandLibinia emarginata

Summary The sperm of Libinia emarginata and Ovalipes ocellatus are characteristic of brachyurans in possessing a large acrosomal complex surrounding the nucleus and its several radiating arms. The radial arms in O. ocellatus do not contain microtubules as do those of Libinia. The spermatophores in both species are spheroidal. In Libinia, they are surrounded by seminal fluids which appear flocculent while in Ovalipes the seminal fluids are globular. The spermatophores surrounded by seminal fluids are transferred at the time of copulation to the seminal receptacle in the female. On the morning following mating, the sperm of Libinia are distributed throughout the interior of the seminal receptacle. In Ovalipes, the sperm are aggregated into discrete masses surrounded by walls apparently formed from fusion of the seminal fluids and spermatophore walls. These differences apparently reflect differences in timing of oviposition and thus fertilization of the eggs following mating.