Hermaphroditic animals—mostly invertebrates such as worms, bryozoans (moss animals), trematodes (flukes), snails, slugs, and barnacles—are usually parasitic, slow-moving, or permanently attached to another animal or plant.
A hermaphrodite is an organism (plant or animal) having both male and female reproductive organs. A plant hermaphrodite, for example, has both staminate and carpellate organs. In animals such as some pulmonate and opisthobranch snails and slugs can act as either the male or female in sexual reproduction.
A rough estimate of the number of hermaphroditic animal species is 65,000, about 5% of all animal species, or 33% excluding insects. Insects are almost exclusively gonochoric, and no definitive cases of hermaphroditism have been demonstrated in this group. There are no hermaphroditic species among mammals or birds.
Roughgarden posits that while animals come in only two sexes, many species have more than two genders. How can this be? Sex refers to the size of the gametes, and, quibbling exceptions aside, sexually reproducing species have only two types of gamete, big and small (eggs and sperm).
Intersex conditions have been described in several domestic animal species. True hermaphrodites are rare and have both ovarian and testicular tissue and exhibit anomalies of the external genitalia. The karyotype is variable and may be a chimera, mosaic, or unknown.
Slugs, starfish, and other creatures also switch gender when it works to their advantage. However, the cues that trigger the change vary from species to species.
Many species of fish, like the kobudai, are known as “sequential hermaphrodites”: they can switch sex permanently at a specific point in their lives. The majority of “sequential hermaphrodites” are known as “protogynous” (Greek for “female first”): they switch from female to male.
The threes sexes of the Pleodorina starrii algae are male, female, and a third sex that researchers call bisexual in reference to the fact that it can produce both male and female sex cells in a single genotype and exists due to normal expression of the species' genes.
But perhaps the most surprising thing about Auanema sp. is that it's found in three sexes – male, female and hermaphroditic. While hermaphroditism is relatively common in the world of invertebrates, this new worm species does things a little differently.
Animals that reproduce asexually include planarians, many annelid worms including polychaetes and some oligochaetes, turbellarians and sea stars. Many fungi and plants reproduce asexually. Some plants have specialized structures for reproduction via fragmentation, such as gemmae in liverworts.
Tetrahymena are oval-shaped protozoa that live in freshwater. These microscopic organisms come in seven different "sexes," or mating types. Any sex can mate with any other mating type except its own. Even more intriguing to biologists is that it doesn't matter what mating types two Tetrahymena parents are.
Some intersex people have both testes and ovaries. You may be able to get pregnant on your own, if you also have a uterus. However, if you have testes, they may be releasing more testosterone than would be optimal for conception and pregnancy.
Background: There are 11 reported cases of pregnancy in true hermaphrodites, but none with advanced genetic testing. All known fetuses have been male. Case: A true hermaphrodite with a spontaneous pregnancy prenatally known to have a remaining portion of a right ovotestis, delivered a male neonate.
This may be in the same gonad (an ovotestis), or the person might have 1 ovary and 1 testis. The person may have XX chromosomes, XY chromosomes, or both. The external genitals may be ambiguous or may appear to be female or male. This condition used to be called true hermaphroditism.
Hermaphroditism occurs rarely in human and animal populations [5]. Only few cases of hermaphrodite have been reported in various breeds of dogs such as Basset hound [2], Cocker spaniel [7] and Pug [8]. Here, we report a very rare case of a hermaphrodite dog.
Clown Fish
Clown fish are all born male, but that doesn't mean they simply do without female counterparts. Rather, some — the most dominant males — turn into females (a process known as sequential hermaphroditism).
Jellyfish are usually either male or female (with occasional hermaphrodites). In most cases, adults release sperm and eggs into the surrounding water, where the unprotected eggs are fertilized and develop into larvae.
Snails called slipper limpets begin life as males, and become female as they grow. A new Smithsonian study shows that when two males are kept together and can touch one another, the larger one changes to female sooner, and the smaller one later.
Greenflies, stick insects, aphids, water fleas, scorpions, termites and honey bees are all capable of reproducing without males, using parthenogenesis.
If a developing worm has two X chromosomes, this gene is activated and the worm will develop into a female. If there is only one X chromosome, TRA-1 is inactivated, causing the worm to become a male.
The New Mexico whiptail (Aspidoscelis neomexicanus) is a female-only species of lizard found in the southwestern United States in New Mexico and Arizona, and in northern Mexico in Chihuahua. It is the official state reptile of New Mexico. It is one of many lizard species known to be parthenogenetic.
Most penguin species are monogamous (one male breeds with one female during a mating season); however, research has shown that some females may have one to three partners in one season and some males may have one or two partners. Mate selection is up to the female, and it is the females that compete for the males.
There are species that are both male and female at the same time. No switching is necessary. Other species of jellyfish – sequential hermaphrodites – are either male and then female, or vice-versa, but not both simultaneously. These are natural transgender jellyfish.
Polyandry also occurs in some primates such as marmosets, mammal groups, the marsupial genus' Antechinus and bandicoots, around 1% of all bird species, such as jacanas and dunnocks, insects such as honeybees, and fish such as pipefish.
A bit confusing, yet generally speaking a unique gland determines masculinity in crustaceans, at least in those species such as lobsters, prawns, crabs and crayfish where sex does not change naturally.