Mammary and Genital Slits
The difference between male and female dolphins can be found out by examining the genital area which is near to the tail of the dolphin.
In females, there is a single urogenital slit, which contains the genital opening, the urinary tract opening and the opening. The mammary slis of the female can be seen beside the urogenital slits. However, some males may also have mammary slits.
In males, there are two openings within the urogenital slit. One of which is a small opening and the other is a genital slit where the penis is hidden. The long retractable penis emerges only when it erects.