According to Ovid, he fused with the nymph Salmacis resulting in one individual possessing physical traits of male and female sexes; Alexander ab Alexandro stated, using the term hermaphrodite, that the people who bore the sexes of both man and woman were regarded by the Athenians and the Romans as monsters, and thrown into the sea at Athens and into the Tiber at Rome.

This contrasts simultaneous hermaphrodites, in which an individual may possess fully functional male and female gonads.

Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates. Historically, the term hermaphrodite has also been used to describe ambiguous genitalia and gonadal mosaicism in individuals of gonochoristic species, especially human beings.

Arthropods are the phylum with the largest number of species.

Most hermaphroditic species exhibit some degree of self-fertilization.

One possible pathophysiologic explanation of this rare phenomenon is a parthenogenetic division of a haploid ovum into two haploid ova.

Upon fertilization of the two ova by two sperm cells (one carrying an X and the other carrying a Y chromosome), the two fertilized ova are then fused together resulting in a person having dual genitalial, gonadal (ovotestes) and genetic sex.

The apparent penis in female spotted hyenas is in fact an enlarged clitoris, which contains an external birth canal.

It can be difficult to determine the sex of wild spotted hyenas until sexual maturity, when they may become pregnant.

Intersex is thought by some to be caused by unusual sex hormones; the unusual hormones may be caused by an atypical set of sex chromosomes.

Sigmund Freud (based on work by his associate Wilhelm Fliess) held fetal hermaphroditism to be a fact of the physiological development of humans.

In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which either partner can act as the "female" or "male".

For example, the great majority of tunicates, pulmonate snails, opisthobranch snails and slugs are hermaphrodites.

When a female spotted hyena gives birth, they pass the cub through the cervix internally, but then pass it out through the elongated clitoris.