Chig

Overview
Chigs (sometimes referred to as Glyphs) are a fictional alien species in the science fiction television series Space: Above and Beyond. Chig is not the species' name for itself, but rather a human-coined nickname (referencing the Tunga penetrans (chigoe flea)). ("The Farthest Man from Home")

Background
Chigs are humanoid, bipedal aliens that serve as the primary antagonists in the series. They appear to be unable to survive in atmospheres that support human life; they are often seen wearing armored life-support systems that provide them with the methane they need to breathe. In addition to providing methane, Chig armor suits also have a built-in suicide mechanism that is triggered when the helmet is forcibly removed, quickly dissolving the Chig inside. In the episode "Choice or Chance", a Chig is apparently able to take human form and interact with other humans in an ordinary atmosphere until killed, when it turns to slime in the manner of earlier Chig deaths. ("Choice or Chance")

How this is achieved is not explained.

Distinguishing characteristics of the un-armored Chig are small black eyes set deeply in the head, pink skin, a lack of a prominent nose, a protruding upper jaw, and structures resembling gills to either side of the mandible.

The series provides little concrete evidence about the Chigs until the last two episodes, choosing to initially present the Chigs as a traditional science-fiction alien enemy out to destroy humanity. Throughout the series, the writers provide several small clues regarding the nature of the Chigs, their motivations, and their biology before devoting the last two episodes of the series to revealing the possibility that Chigs and humans are related species.

History
As the series presents it, known human contact with the Chigs begins when an unmanned probe, launched by the military-industrial corporation Aerotech, lands on a celestial body designated "celestial body 2064K" (later given military designation "Anvil"), the single moon orbiting the Chig homeworld. This moon is sacred to the Chigs because it is where life originated via panspermia and where Chigs still go to be born. ("And If They Lay Us Down To Rest")

The Chigs actually evolved from bacteria that originated on Earth billions of years ago: an asteroid collision threw these bacteria into space, carried by meteorites, where they eventually landed on the Chig sacred moon. Life on Earth had already advanced to the eukaryote stage of development, and the rate of evolution proceeded slightly faster for the bacteria on their new world, allowing life there to evolve to the point that it could produce the sentient Chigs at roughly the same time that modern humans evolved.

The Aerotech probe manages to obtain a limited amount of data before the Chigs send a warning signal through it before destroying the probe. Aerotech, for unknown reasons, apparently chooses to keep this "first contact" a secret from the governments of Earth.

In early 2063, Chigs declare war on humanity, launching what appears to be an unprovoked first-strike against humanity's budding interstellar colonies. These colonists, sponsored by Aerotech and designated the Vespa and Tellus colonies, are attacked and destroyed and the few survivors are taken prisoner. The Chig space forces begin a push straight towards Earth, devastating the unprepared Earth forces. Only the actions of the US Marines Aviator 58th Squadron at the Battle of the Belt prevent Earth itself from falling (the battle was actually fought in the Jupiter Trojan asteroid field at Jupiter's Lagrangian point, not the main asteroid belt). ("Pilot")

Through the element of surprise, superior numbers, and their advanced technology, the Chigs gain the advantage in early battles. Humanity's adaptability and ferocity catches them off guard. The Chigs, who favor large direct military strategies, are unprepared for the guerrilla tactics used by the human forces. Special operations missions, infiltrations, assassinations, sabotage, and small unit engagements all prove effective against the Chig attackers.

The Chigs then enter into an alliance with the remnants of the Silicates, a human-built race of androids, that fled to space after losing the AI Wars on Earth. The exact nature of this alliance is vague and not expanded upon in the series. Just as humans are ready to conquer the Chig homeworld, though, an emissary comes to negotiate for peaceful relations. The emissary reveals that humans and Chigs seem to have a common origin, based on their chemical makeup.

Technology
Chig technology is slightly more advanced than Human technology at the beginning of the series, though only loosely, on the scale of a few decades of advancement (cf. how Nazi Germany had better weapons technology than its enemies at the start of World War II, though mostly because it had been economically focused on military weapons development for several years). Chigs have faster-than-light spacefaring technology and advanced weapon systems. In the show, they use a combination of plasma-based energy weapons and ballistic missiles for their aerospace fighters and capital ships. Chig ground forces use anti-gravity hover tanks, designated T-77s for heavy armor and anti-personnel plasma weapons and flamethrowers.

Study of downed Chig fightercraft in early episodes revealed that they are faster and have a better rate of climb than their human counterparts. However, human Hammerhead fighters have a heavier weapons loadout, and are more maneuverable.

The Chigs also possess large battleships and a destroyer class vessel capable of causing energy spikes within human starships reactors using a specialized microwave energy weapon generator. They also developed a stealth fighter with a hull impervious to standard aerial cannon fire. They also have a red colored fighter that can travel across the gravity field of a black hole.

Culture
Much about the Chigs' society and culture remains unknown throughout the series, presenting them as mysterious and therefore terrifying alien enemies trying to destroy humanity. Their specific command hierarchy and general social structures remain unexplained. From the Chig ambassador's claims in the final two episodes, it seems that they consider the moon they evolved on (codenamed "Anvil" by humans) to be "sacred" in some sense.

One curious practice observed since early in the war with humanity was that whenever Chig infantry encountered the grave of a dead human soldier, they would dig up the body and mutilate the corpse, typically by completely dismembering it. At first, the human military thought this was a terror-tactic, meant to frighten human soldiers with the Chigs' brutality. As the war progressed, it was eventually discovered that while the Chigs may possess some form of "religion" (given that they consider their breeding grounds to be sacred), they never developed a concept of an afterlife. As it turns out, humans are just as much mysterious, terrifying aliens to the Chigs as they are to humans. As the Chigs encountered snippets of human culture, through intercepted radio transmissions or recovered personal effects from dead soldiers, etc., they drastically misinterpreted this alien concept of an "afterlife". This led the Chigs to believe that dead human soldiers will literally spring back to life sometime after their death, and that burying a corpse aids this process. Genuinely terrified of this human "army of zombies", Chig infantry then began to dig up the graves of human soldiers they came across and completely dismember their corpses, to make sure they stay dead. ("Pearly")

"If the Chigs come across the grave, they'll dig it up and mutilate the body. Do you realize they had no concept of a life after death until they heard it from us? My theory is, they believe half of us are living dead - an army of zombies."

Just as humans have applied the derogatory slang-nickname "Chigs" to the aliens, they have their own derogatory slang term for humans. According to their Silicate allies, the term loosely translates as "Red Stink Creature". ("Choice or Chance")

Chigs have green instead of red blood, and smell like sulfur. As it turns out, humans' red blood and non-sulfur smell strikes the Chigs as just as disturbingly "unnatural" as their alien biology seems to us.

Chigs of Note

 * "Chiggy von Richthofen"; named after Manfred von Richthofen, "Chiggy von Richthofen" flew an advanced Chig stealth fighter, with the words "Inferno" (Dante), "Abandon All Hope" written in English on its hull. Its armor was impervious to standard cannon fire and was a superior vessel to Earth fighters and destroyed dozens of them. "Chiggy von Richthofen" was killed in a dogfight against Lt. Col. T.C. McQueen. McQueen used missiles to breach the armor of the fighter.
 * Chig Ambassador; A Chig envoy sent alone and putatively unarmed to the USS Saratoga to negotiate an end to hostilities between humans and Chigs. It was equipped with a translation device capable of producing English. The Chig attempted to explain the circumstances of the Vesta and Tellus colony massacres, blaming Aerotech CEO E. Allen Wayne for desecrating the sacred moon of their homeworld with an unmanned probe. When Wayne refused to admit to the act, the Chig attacked him, resulting apparently in an explosion that killed him, Wayne, and several top Earth military officers. Whether it was a hidden bomb - an emergency resort or an assassination device - or the mixing of methane and oxygen exploding after a gun fires, is never clarified.