Oysters are able to change from one gender to another and back again
The male firefly's light is twice as bright as a female's
If the movie 'Finding Nemo' were scientifically accurate, Nemo's dad would have become female after Nemo's mom died. Then he would have mated with his son.
Horses reveal their gender in their teeth --- most males have 40, females 36
Slugs have both male and female reproductive organs.
Aztecs were one of the few ancient civilizations where education was mandatory for everyone, boys and girls from all social status were educated at home and later at schools
Earthworms are hermaphroditic, containing both male and female organs
A queen bee is created by a few randomly selected larva (irrespective of gender) being fed Royal Jelly to make them develop queen morphology
Turtles give away their gender by the noise they make. Males grunt and females hiss
Oysters can change from one gender to another and back again.
Sand temperature determines the gender of baby sea turtles