Arachnopods were semi-intelligent bio-engineered arthropods. They were recorded in Bor Pollag's Book of Alien Monsters.
The creatures were ravenous, considered by many to be indestructible, and able to detach and reattach their limbs. Any limbs they were unable to reattach would be eaten and regrown. Each part of an Arachnopod's body had its own consciousness which worked together in the goal to find food, which it referred to as "eats". The head governed the other consciousnesses as it had the mouth, but the other limbs could act on their own out of hunger.
Ten Arachnopods were being taken to a prison planet on the Montressor in 2815 when the spacecraft got stuck in a hyperspace tunnel. They escaped confinement and ate everyone trapped in the tunnel except the ones taken to the year 3012 by the Repulsion. When they had nothing else to feed on, they ate each other. The Fourth Doctor and Romana II were able to escape the remaining five of them by rotating the artificial gravity in the Cerberus, causing them to fall into the hyperspace-real-space interface and be obliterated into sub-atomic particles. (PROSE: Festival of Death)