Andorian

The Andorians were a blue-skinned species from the Alpha Quadrant, and one of the founding members of the. One of their most recognized physical features were their antennas and white hair.

Homeworlds
The original Andorian homeworld is the natural satellite Andoria, which orbits the gas giant Andor in the Procyon, or Alpha Canis Minoris, system. Andoria's surface is icy and rarely if ever thaws. (ENT)

The Andorians have two "homeworlds" in the Epsilon Indi system, Epsilon Indi IV and Epsilon Indi VIII. These originated as colonies. (The Andor Files)

Epsilon Indi IV has temperate areas with tree-like vegetation and large carnivores. The tidal effects of Epsilon Indi's binary brown dwarf companion makes it geologically unstable.

Physiology
Andorians are human-shaped and almost always have light blue skin and white or silver hair. (Starship Exeter, Starship Independence, Star Trek: Pendragon, Star Trek: Remington, )

There is a sub-species, the Aenar, who are white-skinned, blind, and telepathic.


 * Other colours have been seen. In TAS, Andorians are muddy grey, but this is because of a production error. In TNG, an image of a female Andorian is greenish, but this also looks like a production error. In, John bet-Orlek is a darker blue, but it has not been explained whether this represents a subtype of Andorian or is some unique condition.


 * The suggestion in Starfleet Medical Reference Manual (Ballantine, 1977) that Andorians have a partial exoskeleton has no support in canon, although an Andorian so endowed was illustrated in "The Dragons of Berengaria: Part Two" by Brian Franczak in Enterprise Incidents #8, 1980. On the other hand, the Manual also suggested Andorians don't have ears, which has since been contradicted.

Antennae
Andorians' antennae have several functions.

They sense fluctuations in gravity, useful for beings living underground on a geologically unstable world. Extreme gravity disturbances can cause pain or unconsciousness. (Starship Exeter: "The Tressaurian Intersection")

Reproduction
Andorians reproductive organs are normally entirely retracted and the sex of some Andorians can be difficult to discern to outsiders. In some Andorian societies, Andorians are treated as neuter until they marry. In others, individuals are treated as sexed from childhood. (TNG novel The Devil's Heart, "A Summary of the Physiological Roots of Andorian Culture", )

Depending on whom you ask, Andorian reproduction involves two people with two roles each in the reproductive process, or there are four people required who each do one thing. These might be different social conventions built on the same biological facts. Two-person mating is prolific, whereas the four-person mating entails a narrow window of fertility and low birth-rate. ("A Summary of the Physiological Roots of Andorian Culture", DS9 Relaunch novels)

In the 22nd and 23rd centuries, some Andorians at least describe themselves as male or female, at least in discussion with non-Andorians, and form male-female pair-bonds. (ENT)

By the late 24th century, the four genders thaan, chan, shen, and zhen are used in general conversation, and four-person bonds are rigidly enforced by the dominant Andorian culture, with severe social penalties for non-compliance. This leads to a declining birth-rate and fears of a population crash. (DS9 Relaunch novels)

In the 23rd century Andorians from both traditions are encountered. 

Society
On the ice-covered planet Andoria, settlements are underground, heated by geothermal energy and connected by tunnels thousands of kilometers long. (ENT)

On Epsilon Indi IV, the tradition of living underground is still followed, even though it has a habitable surface. (Starship Exeter: "The Savage Empire", "The Tressaurian Interesection")

Many Andorians know the martial art ushaan, which employs the ushaan-tor (an ice-cutting tool) or chakra. (Starship Independence: Sharvetra Pooth'kiph's bio)

Marriage and full names
Andorian marriage involve four people, except when they do not. 

In the main Andorian language the four participants are referred to as thaan, chan, shen, and zhen, and these are used as prefixes in their full formal names (as in ThorshkukJini zh’Thresh, where Thresh is a clan name). The name used in a Starfleet context  may be part of their personal name (as in "Lieutenant Jini") or their prefixed clan name (as in "Lieutenant zh'Thresh"); it depends on the individual Andorian. (Starship Independence, Star Trek: Pendragon, )

Other Andorians have names that do not fit that pattern. (Starship Exeter, Star Trek: Remington, )

Cultural products

 * Andorian blues (Pooth'kiph's bio)
 * Andorian silk painting (Pooth'kiph's bio)
 * Andorian tile painting (Pooth'kiph's bio)

Food and beverages

 * Andorian frost eel
 * Andorian rime leaf
 * Andorian tuber root (Pooth'kiph's bio)

People

 * List of Andorians

Canon series

 * The Original Series
 * The Animated Series
 * Star Trek: The Next Generation
 * Star Trek: Enterprise

Movies

 * Star Trek: The Motion Picture
 * Star Trek IV: The Voyage Home
 * Star Trek V: The Final Frontier

Star Trek fan films

 * Starship Exeter

Fan fiction

 * Star Trek Mirror Wars

Fan comics

 * TOSS
 * Star Trek: The Animated Series Comics
 * Star Trek: Phoenix-X (comics) - Comic 4.1, "Secret Engine"