Zergling

The zergling was the basic warrior strain of the zerg, serving as the Swarm's frontline assault troops. The most numerous of all zerg mutations, zerglings attacked in large groups under the direction of larger warriors, embodying what the word "swarm" meant to terrans across the Koprulu Sector. Individually little more than feral animals roughly the size of a large dog, they overwhelmed their enemies through expendable numbers and raw speed.

Origin and physiology#

Zerglings were evolved from the Zz'gashi dune runner after that species was assimilated into the zerg Swarm. Though the dune runner supplied the strain's core genetic code, the zergling was hybridized from over fifteen other organism strains, with the dune runner DNA distilled down to its simplest possible form. That simplicity was the strain's defining trait. The reduced DNA allowed two zerglings to be spawned from a single larva, which drew its genetic information from the primordial ooze of the spawning pools, and made the strain so efficient to reproduce that it thrived even under mortality rates greater than almost all other zerg strains. The same simplicity allowed rapid mutation and adaptation to a wide range of environments.

The zergling was the smallest mainline strain apart from the larvae and the chitha. Standing about one meter tall and equivalent in size to a large dog, it possessed webbed feet, sickle-shaped limbs, and sharp incisor teeth used primarily to tear into flesh. Its skin was tough and leathery, preventing moisture loss while still allowing circulation to regulate body temperature, and its nutrient storage system let it derive the compounds necessary for life, including water, from almost anything it ate. This efficiency allowed a zergling to operate away from a hive cluster for extended periods.

A zergling's eyes had a complex optical structure with an aperture that allowed it to see in the dark, an ability enhanced by a reflective tissue layer and a substance that made the eyes glow orange or red as its vision adapted to low light. Its spiked tail served to maintain balance while it ran at high speed, though the spikes themselves had no clear purpose and Dominion scientists believed them vestigial from the dune runner. The strain was physically adaptable, able to climb near-vertical surfaces and move at extraordinary speed, but individual zerglings were fragile and easily exterminated.

Mutations and refinement#

The Swarm continually refined the zergling. A metabolic boost altered the creature to increase its reflexes and rate of movement, while a mutation of its adrenal glands changed its glandular balance to induce a battle frenzy. These adrenal glands were unusually large for a creature of the zergling's size, and the genetic manipulation behind them also heightened the strain's aggression, driving it into a frenzied state in which it could bring down armored vehicles and structures with ease. Terran Dominion marines referred to such enhanced zerglings as "speedlings."

The zergling's nervous system was hyperactive to such a degree that those enslaved by the Cerberus Program required two antennas each to control their movement. By the Second Great War, some zerglings were observed to possess venational wings used to increase ground acceleration. Zerglings of the Leviathan Brood grew spikes from their bodies as a byproduct of their extremely simplified DNA, and these spikes were retained even when such zerglings metamorphosed into banelings.

Role in the Swarm#

Zerglings truly embodied what the word "swarm" meant to the zerg. They moved and attacked in large groups ranging from a dozen to a hundred, serving as living shields for more powerful strains while also overwhelming their foes through sheer weight of numbers. Individually they were feral animals, but under the command of larger warriors they moved as one mind, ripping enemies apart with their sickles and fangs. When paired with roaches, they could prove nearly unstoppable against terran infantry lacking siege tank or bunker support. Zerglings generally hunted and patrolled in pairs.

Outside of direct combat, the strain's raw speed and expendability suited it for reconnaissance. Lone zerglings served as scouts and lookouts, sometimes accompanied by a retinue of hydralisks when scouting far from a hive cluster.

Evolution into the baneling#

Zerglings continued to evolve after the conflict on the dune runners' homeworld, gaining the ability to metamorphose into the baneling. This evolution arose from an experiment the zerg conducted at the Dominion colony of Sorona, where the Swarm incorporated a native acidic mold into the zergling's body structure to produce a creature filled with corrosive payload. The new breed that controlled the Swarm directed this development, and the baneling thereafter remained the zergling's principal evolved form.