shu

"In mermaids, reproduction is much like that of dolphins. The reproductive organs of both the male and female are akin to the dolphin and whale, and mermaid babies are born live (as opposed to hatched from eggs).

Females have human internal reproduction organs; however the vagina is slightly shorter, and the common urogenital opening (the urethra merges with the vaginal canal near the opening) is at the front. The opening can stretch as much as a human vaginal opening; mermaid babies are born live. A clitoris (which is the same color as the tail) is slightly below the urogenital opening, and an anus is above the urogenital opening. Mermaid vaginas are slightly smaller than human ones (since merman penises are smaller, explained below), so they tend to be more sexually satisfying to human males.

Males do have a penis, but it is almost as small as a human female clitoris and is the same color as the tail; it is hardly visible (this is the only plausible explanation to why no one has ever seen a penis on any of merman). It is used for urination, as well as sexual intercourse. The testicles are inside the tail, as opposed to the pelvis, since they require a slightly lower temperature to function properly (the human and pelvis part is warm-blooded, but the tail is cold-blooded). The anus is above the penis."