Alien Species
Tractators

The Tractators are a docile grub like species with a control over gravity. Essentially docile, in the presence of the Gravis they combine to form an intelligent hive.

The fifth Doctor encountered the Tractators on Frontios where they had lured a group of human colonists in order to use their bodies and minds to operate excavating machinery. As well as Frontios they have also attacked other planets, one of which being Turlough's home planet Trion.

The Doctor managed to rescue the colony by seperating the Gravis from the rest of the Tractators, returning them to their docile state. He then let the Gravis loose on an uninhabited planet.

Television adventures featuring Tractators:

Frontios

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