 Their unique genetic-adaptations made assimilation into "The Swarm" difficult, as they were shown as able to absorb "swarm-essence" to mutate counter-measures.Their highly individualistic nature avoided incorporation into the Zerg Swarm's swarm intelligence.Dehaka is a primal Zerg pack leader from Zerus who is fixated on adaptation and collecting raw genetic material, which he refers to as "essence"; for Dehaka, "essence" is survival against extinction.