The genital opening is usually located on the underside of the second abdominal segment.

They are fertilised as they pass out of the genital opening.

They often sever their mating organs, which are then found stuck in the female genital opening.

They have eight pairs of walking legs, with their genital openings situated in the top segment.

The only visible distinctions between males and females are the genital openings.

The mating of this species is in head-to-head position with genital openings to each other.

But this arrangement means that the baby, when it first emerges from her genital opening has to make a marathon journey.

The genital openings are located on the fourth body segment, but the animals do not copulate.

Also, they may evolve shield over their genital openings to prevent intromission.