and has longer legs that allow it to move much faster and climb walls. It does not have a beak, instead using sharp talons at the ends of its legs to latch onto hosts. The zombies it creates are stripped of most of their flesh and muscle. When a fast headcrab is shot off a zombie, it will reveal a completely bare skull with no tissue, which suggests that the fast headcrab completely takes over control of the host's muscles and nervous system, becoming the potential brain for the host/zombie. The resulting zombies are, like the headcrab itself, much faster than ordinary zombies. It also makes the same shriek as its standard cousins. Poison headcrab In-universe, the poison headcrab (also known as the black or venomous headcrab) is slightly larger with dark sage-green-colored skin and thick hairs on the joints of its body and inward-bending legs. It has white bands that encircle its knee joints, wider legs, and a more flattened body, giving it a generally more crab-like appearance. It also makes a chirp at range and a hissing-rattling similar to that of a rattlesnake's tail when it detects a host. Immediately before pouncing, they emit a loud, distinctive shriek. There is also a whipping noise as they pounce. Unlike other headcrabs, the poisonous headcrab has some survival instinct, and retreats if injured. Although it is the slowest-moving version of the headcrab when calm, it can outpace an ordinary headcrab when retreating. Another difference is that the poison headcrab takes a longer time to burn to death than the other types. Poison headcrabs get their name from the neurotoxin they carry, which reduces the player's health to one point instantly on contact, meaning that any third-party damage would kill the player. Gordon's HEV suit provides an antidote that gradually restores lost health over a short period, minus the damage caused by the attack itself. While this makes a single poisonous headcrab difficult to fully kill Gordon, it can make survival more problematic if other enemies are present. Half-Life 2: Raising the Bar notes that play-testers would prioritize poison headcrabs as targets, regardless of any other present or tougher dangers. They will group up on a single host once one is found: the attacking poison headcrab controls the host, while the others use the new host as transportation. Once an enemy is found, the poison headcrabs that use the host as