During the final stages of a Tyranid invasion, they scour the entirety of a planet, ingesting all biological material on the planet and leaving only an empty and desolate wasteland. Eventually, the Rippers will become bloated full of biomass, unfit for combat. At this point, they simply crawl into Tyranid Digestion Pools at the bases of Capillary Towers, where they and the bio-mass they have fed upon are broken down and absorbed by the Hive Fleet for the creation of new Tyranid organisms and structures. However, in some cases they may be evolved by a Norn-Queen to perform more advanced functions for the swarm depending on the genetic material they have absorbed.
In some instances, Hive Ships have been driven away from a world by its defenders, leaving Tyranid ground forces left behind on the planetary surface isolated from the Hive Mind. In such circumstances, Rippers have been known to burrow below ground and then spend the time using their absorbed biomass to metamorphose into more advanced Tyranids. This has led many of the Adeptus Mechanicus' Magi Biologis to believe that Rippers are an immature form of the Tyranid. This would mean that Rippers are theoretically capable of evolving into any other type of Tyranid bioform when given the right signals from the Hive Mind, potentially allowing Rippers to transform into any known Tyranid, from a Hormagaunt to a Carnifex.
Rippers have serpentine bodies approximately half a metre long that terminate in a broad head above a set of vestigial gripping claws. The head is split by a wide mouth filled with rows of razor sharp teeth. The Ripper’s powerful jaws can bite through flesh and bone with alarming ease, and they have been known to gnaw their way through plasteel to reach food. Rippers are energetic and fearless organisms, quite capable of pulling down creatures many times their own size, from a rampaging Grox to an armed man. Once a Ripper's jaws tighten around its prey, they stay clamped shut until a mouthful of flesh is torn away or the Ripper is slain.
- Sky-Slasher - Sky-slashers are Rippers adapted to allow flight with the addition of bat-like wings.
- Eel-like Ripper - A currently unnamed variant of the Ripper that has been designed to devour all aquatic biomass on a world targeted by a Tyranid Hive Fleet for consumption.