The Arachnid race evolved on the planet Closta from an ant like species. Around 11,000 years ago they evolved beyond the hive-mind and the individual was born. Because the Arachnids come  from a hive-mind they are more susceptible than other races to deception tactics like the phantom projections of the Aleos, for example.

Despite their "unsettling" appearance, the Arachnids are probably the most enlightened and peaceful of the Galactic races. Despite this, they will not shy away from a fight when threatened. They are extremely agile and can wield 4 weapons simultaneously giving them a big advantage in battle.

In 2455 Arachnid bio-technology reached the point where space travel was possible. The first interstellar Arachnid organic ship was called "Sorata". It established their first colony on the planet Trevator in the neighboring system. Two years later the colony was discovered by the Lur'eyan. In 2462 the Arachnids joined the Alliance.

In 2516, during the Rok war, Closta was attacked. The Arachnids successfully defended their world for over a month. By that point, the only objective of the Rok garrison was to contain them on the planet and not let them reinforce the Alliance fleets. After word of the attack finally reached the Alliance, they sent a battle group of Dreadnoughts to liberate Closta. After the siege was ended, the Arachnids were finally free to reinforce the Alliance fleets and re-join the battle against the Rok.