Extremely powerful parasitic creature which invaded the planet Vortis. It arrived in the depths of the flower forest, and had firmly established itself before the native Menoptra knew it was there. By this time it was too late to attack it. It turned the normally docile Zarbi against the Menoptra, forcing them to abandon their world for the planet Pictos. The Animus could generate gravitational fields, powerful enough to attract several small moons into Vortis' orbit. It could also influence people's minds using gold as a conduit. All the vegetation was cut down and fed into acid pools to feed the growth of the Animus' domain - the Carsinome. This was centred on the planet's magnetic pole.
The Animus appeared as a huge tentacled creature, residing at the heart of the Carsinome. When it communicated with the Doctor, it used a female voice.
The Menoptra returned to claim their planet, bringing with them a weapon called the Isop-tope. This was a cell destructor. The Animus was about to absorb the Doctor's mind, so that it could master time travel, when Barbara used the weapon on it - destroying it. The Carsinome dissolved, and the Zarbi reverted to their docile state.
Voiced by: Catherine Fleming. Appearances: The Web Planet (1965).