The act of sexual reproduction typically requires the usage of sexual organs which, in most species, are differentiated for males and females. Differing organs for each gender allows interspecies reproduction between genders of differing species in addition to the more common reproduction processes within the same species. Alternatively, DNA extracted from a male could be used to impregnate a female without the use of the sexual organs. (VOY: "Maneuvers")
Sexual reproduction processes by species
Arkarian horn fowl
Arkarian horn fowl, native to the planet Arkaria, had mating habits of particular interest to ornithologists. Commander Calvin Hutchinson found the practice of particular interest. (TNG: "Starship Mine")
- Commander Hutchinson did not elaborate on what made the mating practices interesting, as Captain Picard cut off the conversation with the talkative commander soon thereafter.
While speaking of copulation, Seven of Nine noted that the Borg opt for assimilation and do not require sexual reproduction of any kind, specifying; single cell reproduction and seduction. (VOY: "Revulsion")
In the Human species, the males and females have different sexual organs. The male inseminates the female, who in turn carries the baby. Commander William T. Riker commented that the act of human reproduction brings a closeness and intimacy between the man and woman, and is "a very pleasurable experience." (TNG: "The Outcast")
The J'naii species sexually reproduce by incubating fetuses located in fibrous husks which both parents inseminate. The J'naii considered this method of reproduction less risky and less painful than the processes used by other species, though Soren claimed the process was extremely pleasurable. (TNG: "The Outcast")
The Taresian species' process of sexual reproduction (joining) removed so much DNA from the male that it resulted in the male's death. To sustain their numbers, Taresian women lured unsuspecting males from different alien species to their homeworld. (VOY: "Favorite Son")
Varro traditionally mate for life. When two Varro have intimate relations, they experience olan'vora - "the shared heart". This makes their body chemistry interdependent, causing withdrawal symptoms if the two people separate. The effect gets stronger with each mating and separation can be fatal. (VOY: "The Disease")
See Pon farr.
The corporeal ancestors of the Wisps required mates to reproduce (like Humans), but eventually evolved past this requirement. In 2151, Wisps inhabited several crewmembers of the Enterprise NX-01, claiming they wanted to learn how their ancestors lived. (ENT: "The Crossing")