The Mutalisk is an airborne breed of Zerg. They are primarily hunter/killers in nature. They are comparable with air superiority aircraft. Oddly, Mutalisks are able to survive the rigors of space without any protection from the vacuum, besides their skin. Mutalisks require a Spire in order to hatch.
Mutalisks look like winged lizards. They look somewhat like Wyverns from Human mythology. However, they lack legs. Mutaliks are airborne Zerg, and never touch the ground, even to rest.
Mutaliks should not be used apart from the swarm, as they are supposed to play a support role. However, they are extremely effective scouts, not bound with traversing on land.