Voracious Craw

Voracious Craw were worm like creatures.

Biology
Craws resembled tapeworms. They grew to huge sizes, looking like a continent when viewed from space. Craws were permanently hungry, and would eat everything that they could, be it animal, mineral or vegetable.

Anything below the mouth of a Craw was pulped and channelled into the mouth itself, but the Craw did not actually touch the food. The disturbance of a Craw moving sent technology haywire.

When a Craw arrived at a planet, the first thing that it did was check to see if another Craw had arrived there first. If one had not, the Craw then proceeded to devour everything on the planet that it physically could. If it met another Craw, the larger one was left to feed and the smaller one left. (NSA: Sick Building)

History
A Craw began devouring Tiermann's World. It was headed for the Tiermann family home, the only settlement on the planet. The Tenth Doctor, Martha Jones and Solin Tiermann used the amplified sound of burps to mimic another Craw. This scared the present Craw away. (NSA: Sick Building) The sound of a larger Voracious Craw can be modelled by playing back and distorting human burps, and this technique was used to great effect to save the inhabitants of Tiermann's World. (NSA: Sick Building)

Behind the scenes

 * The cover of Sick Building shows the Craw with teeth but this is not so.
 * Voracious means "ravenous" or "greedy".

Voracious Craw