"Native karak species of Calus. Evolved powerful quadriceps to adapt to the rugged environment. Leaps through the air to attack foes."

- Leaping Karak description(src)

The Leaping karaks of Calus were a unique form of the overall species.

They had developed, over the course of generations, powerful leg muscles to aid in their survival in the cliff-filled regions of their home planet. Abathur discovered their unique essence and wished to incorporate their genetic material into the base zergling strain.

Plot branch : Kerrigan chooses to evolve the zergling

After Kerrigan chose to evolve the zergling strain with the karak's essence, Abathur incorporated the genetic material from the corpses of the Calus karaks into the Swarm creating the raptor zergling strain.[1][2]


  1. Blizzard Entertainment. StarCraft II: Heart of the Swarm. (Activision Blizzard). PC. Mission: Heart of the Swarm, Zergling Evolution (in English). 2013-03-12.
  2. Blizzard Entertainment. StarCraft II: Heart of the Swarm Map Editor. (Activision Blizzard) (in English). March 12, 2013