The slothien (a.k.a. "caterpillar cows")[1] were soft-ribbed,[2] peaceful, caterpillar-like herbivores, making their homes in large nests. This changed with their assimilation into the Zerg Swarm, becoming the nightmarish hydralisks. Even their nests were corrupted.[3]

It is known that slothien possessed urticating hairs,[4] which were coated in a mild paralytic venom to ward off predators.[2] These hairs formed the basis for the hydralisk's deadly needle spines.[4] Their thick mandibles were subjected to forced evolution to increase their effectiveness,[2] and their soft ribs were hardened via biochemical manipulation into the hydralisk's scythe-like claws.[5]

The protoss are aware of the slothien and their assimilation by the Swarm. The Terran Dominion learnt of them through obtaining these records,[1] and carried out further studies.[2]


  1. 1.0 1.1 Maxwell, Matthew. "The Teacher." (Feb. 20, 2013). Blizzard Entertainment. StarCraft Lore: The Teacher Accessed 2013-02-20.
  2. 2.0 2.1 2.2 2.3 2014-09-25, Hydralisk Science. Blizzard Entertainment, accessed on 2014-09-27
  3. Underwood, Peter, Bill Roper, Chris Metzen and Jeffrey Vaughn. StarCraft (Manual). Irvine, Calif.: Blizzard Entertainment, 1998.
  4. 4.0 4.1 StarCraft II-Hydralisk. Accessed on 2008-03-10
  5. Blizzard Entertainment. StarCraft II: Heart of the Swarm. (Activision Blizzard). PC. Mission: Heart of the Swarm, Roach Evolution (in English). 2013-03-12.
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