Hydralisk

A hydralisk is a unit in Blizzard's real-time strategy (RTS) game Starcraft, deriving its name from its serpentine body. Spitting needle spines, the hydralisk is the ranged ground soldier of the Zerg race, quickly produceable in the Zerg Hatchery requiring only a Hydralisk Den. As with most Zerg units, the hydralisk is most effective en masse. In SC cenimatics the Hydra uses its sythe like front arms to attack.

Counter-Measures

You may find usefull to use tanks/marines or zealots/dragoons in early games to stop Hydralisk attacks. In an early Zerg/Zerg games, Hydralisks may only be stopped by other, larger Hydralisk groups. In long games you can use Zerglings with the Defiler´s Dark Swarm.

Good Tactics

Try Dropping a few of these near the minerals of your opponent. This will slow his resource gathering a lot, letting you being able to prepare a good attack strategy(works not so well on other zerg, as they can produce large amounts of Drones quickly).