Most zerg structures need to be on creep to stay alive. If any structure is not on the creep they will slowly die. Only Hatcheries, Overlords and Creep Tumors can generate creep.
Hatchery
Spawns larva, creates creep and the primary zerg structure.
Lair
The second level of the Hatchery. Allows Hydralisks and Infesters to be created.
Hive
The final transformation of the Hatechery. It has high health and allows Ultralisks to be created.
Infested Command Center
This structure does not spawn suicide soldiers and it is only seen in the campaign.
Spawning Pool
It allows the spawning of Zerglings and offers upgrades such as increased movement.
Extractor
Cost 35 minerals.
Evolution Chamber
Contains research upgrades for burrow (unlocks burrow), slime (Overlord), generate Creep (Overlord – this ability also increases Zerg buildings' Creep generation speed), and allows the Queen to produce Shriekers, increasing the range of the Sunken Cluster and Swarm Cluch abilities.
Hydralisk Den
Unlocks the Hydralisk and researches attack and armor upgrades for them. It can mutate into a Deep Warren, enabling Lurkers to be developed.
Deep Warren
It is evolved from the Hydralisk Den and is required for the development of Lurkers, also providing upgrades for them.
Spire
Required to build flyers.
Greater Spire
Required to build brood lords.
Ultralisk Cavern
Required to build the Ultralisk which can defeat Archons and Colossus.
Infestation Pit
Allows production of Infesters.
Infested Barracks
This structure is seen in the campaign only. It must be destroyed in mission Outbreak.
Infested Supply Depot
This structure is seen only in the campaign. It must be destroyed in mission Outbreak.
BAneling Nest
It allows Zerglings to morph into Banelings and contains Baneling upgrades (increased weapons and armor).
Roach Warren
It enables the spawning of Roaches, and contains Roach upgrades (increased attack and armor).
Nydus Worm
A worm that pops out of the ground at any location and spawns creep around it. Whats worst is that it can deliver any zerg to any location including Ultralisks.
Spine crawler
Powerful against ground units. Can uproot itself to move to a different location.
Spore Crawler
Has high health(400) and is best against air units. Can move to a different location.