Hermaphroditism

In zoology, a hermaphrodite is an organism of a species whose members possess both male and female sexual organs during their lives. In many species, hermaphroditism is a normal part of the life-cycle. Generally, hermaphroditism occurs in the invertebrates, although it occurs in a fair number of fish, and to a lesser degree in other vertebrates. more...

See below for use of the term in plants.

Note: The term "hermaphrodite" has historically been used to describe people with ambiguous genitalia or biological sex. The broader term intersexual is often used and is preferred by many such individuals and medical professionals. The term is still used by the pornography industry, though often as a synonym for transsexual, as true human intersexuals are rare.

In animals

• Sequential hermaphrodite: The organism is born as one sex and later changes into the other sex.
  • Protandry: When the organism starts as a male, and changes sex to a female later in life.
    • Example: The seabasses (Family Serranidae). These are a highly sought food fish complex made up of primarily groupers. Since even a small male can produce more than enough sperm to fertilize a huge number of eggs, while a female's egg output increases greatly with an increase in size, this strategy makes sense for an organism (fish in general) where over 90% of the eggs laid will not result in a fish that reaches sexual maturity. It has been shown that fishing pressure actually is causing a change in when the switch from male to female occurs, since fishermen naturally prefer to catch the larger fish. The populations are generally changing sex at a smaller size, due to artificial selection.
  • Protogyny: When the organism starts as a female, and changes sex to a male later in life.
    • Example: Wrasses (Family Labridae) are reef fish that tend to have three distinct sexual types. Small females, immature males and supermales. The small females and the immature males have identical colorations. The supermale is usually brightly colored, and there is only one in a given area of the reef. This supermale dominates the other wrasses of the species, having the choice of females to mate with. When the supermale dies, the largest wrasse in the area, male or female, becomes the new supermale.

• Simultaneous hermaphrodite (or synchronous hermaphrodite): The organism has both male and female sexual organs at the same time as an adult. Usually, self-fertilization does not occur.
  • Example: Hamlets, which (unlike other fish) seem quite at ease mating in front of divers, allowing observations in the wild to occur readily. They do not practice self-fertilization, but when they find a mate, the pair takes turns between which one acts as the male and which acts as the female through multiple matings, usually over the course of several nights.

• Gonadal dysgenesis, a type of intersexuality formerly known as "True Hermaphroditism", occurs in about one percent of mammals (including humans), but it is extremely rare for both sets of sexual organs to be functional, usually neither set is functional. In many cases, these manifestations are altered, sometimes only cosmetically, to resemble standard male or female anatomy shortly after birth.

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