Standard Headcrab

The headcrab, also referred to as "head-humpers" by Barney Calhoun and "parasitics" by the Combine Overwatch, are the most numerous and arguably iconic aliens in the series.

At present, there are three different headcrab variations (two of which were introduced in Half-Life 2), all possessing the ability to attach to humans and transhumans to form zombies.

Physical description


Often referred to as a normal, original or classic headcrab to distinguish from the other two headcrab species, it is a small creature consisting of a small rounded body with four legs for movement (two stubby legs at the front, obscured by its claws, and two hind legs at the back; see pictured example to the left) and a pair of larger frontal claws for attacking prey or as additional support when standing still. Under the headcrab's body is a large rounded mouth surrounded by pointed flesh (which also includes the headcrab's stubby front legs) with sharp claw-like "beaks." As such, it is often assumed that the headcrab only walks with its large front claws and hind legs, while the stubby legs only form part of the headcrab's mouth.

Headcrabs also have a mottled tan-colored skin and reddish legs (although this may simply be blood coloration). The headcrabs found in Half-Life are noticeably smaller than those in Half-Life 2 which have bodies approximately the size of a watermelon. A Valve site selling plush headcrabs describe 6 inches as being quarter-scale, implying that headcrabs are typically 2 feet in length.

Although small, slow-moving, relatively weak on its own, and even seemingly harmless with its tip-toe like gait, the headcrab has the ability to quickly leap long distances using its hind legs, while tilting upwards to face its mouth towards its target, inflicting minor injury with its claws, legs, and teeth. Its main goal, however, is to attach itself onto an appropriate host body.

Curiously, although Half-Life 2's headcrabs are capable of tolerating areas contaminated by toxic waste and radioactivity, they are unable to swim and survive in liquid substances (including water); these traits are reversed in Half-Life. The headcrab's resilience towards toxic and radioactivity materials appears to be passed on to the hosts they parasitize, as zombies are frequently found in conditions that would otherwise be hazardous to their hosts. Even if a zombie is submerged completely under toxic waste or water, it will take at least a few minutes for it to die.

Headcrabs have been observed to be prey by bullsquids, Vortigaunts, and barnacles. Headcrabs have also been seen cooked and prepared in different dishes by Vortigaunt chefs in Black Mesa East, which suggest that they are used as a common food source after the extinction of most of earth's species. Citizens in Half-Life 2: Episode One who comment that "they don't taste like crab".

Behavior
Headcrabs frequently lie and wait in dark corners and ventilation shafts for unsuspecting prey to walk by. In more open environments, headcrabs are known to bury themselves in the ground to hide, undetected, then climb out to the surface and attack when a victim draws near. Headcrabs are often seen clustered in groups. They will pursue their prey under the most dangerous conditions, moving through dangerous areas or towards hostile prey with little concern for the consequences, even as their fellow headcrabs die in front of them.

Headcrabs can produce a variety of vocalizations. When they are not hunting, headcrabs usually emit squeaks and fairly quiet, repetitive calls while gently swaying their bodies back and forth. When attacking, headcrabs emit a sharp, shrill shriek as they leap towards their victims.

In Half-Life, headcrabs were found to have originated from a giant creature named Gonarch (also known as "Big Mama"), which shares similar physical qualities with headcrabs. Underdeveloped "baby" headcrabs spawn at a rapid rate from a sac that dangles beneath the creature.

Fast headcrab and Poison Headcrab
New to Half-Life 2 are two previously unseen varieties of headcrabs. It remains to be seen if they are native to Xen (as they never appeared in Half-Life) or are result of genetic manipulation of the original form by the Combine.

While appearing similar to the original headcrab, both headcrab variations differ in a sense that they strictly use their four longer limbs for movement, attacking and standing, as opposed to six from the original headcrab.

Combine application


In Half-Life 2, the Earth-occupying Combine alien race is seen utilizing headcrabs as a form of biological weaponry against the Resistance. "Headcrab shells", as they are known, are shells containing several headcrabs, fired from launchers (only one is featured, in Half-Life 2: Lost Coast, but there are likely to be more such launchers), and its payload released into the open shortly after impact, free to infest or kill nearby victims. If released in large numbers, the shells are highly effective in neutralizing a large concentration of Resistance groups, as proven during a visit to the devastated town of Ravenholm. Standard headcrabs and fast headcrabs have been observed emerging from headcrab shells that have been launched, however poison headcrabs have only been seen emerging from unlaunched headcrab shells during Lost Coast and in the chapter Exit 17 of Half-Life 2: Episode One.

The Combine's mechanism for obtaining large numbers of headcrabs for use in these shells was revealed in Half-Life 2's 2003 code leak, in which a model of an amputated Gonarch sac could be found suspended in a Combine-built frame. Officially however, no reason has been given.

Chapter Locations

 * Half-Life - 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 16
 * Opposing Force - 1, 2, 3, 6, 7
 * Blue Shift - 2, 3, 4, 5
 * Half-Life 2 - 3, 4, 6, 7, 8, 9, 10, 11, 12, 13
 * Half-Life 2: Episode One - 3, 4
 * Half-Life 2: Episode Two - 1, 2, 3, 4, 5

Spawning in-game
Point at ground where you want it to be created and type: npc_create Entity Name
 * Half-Life: monster_headcrab
 * Opposing Force: monster_headcrab
 * Blue Shift: monster_headcrab
 * Half-Life 2: npc_headcrab
 * Lost Coast: npc_headcrab
 * Episode One: npc_headcrab
 * Episode Two: npc_headcrab
 * Portal npc_headcrab
 * Obsidian Conflict: monster_headcrab or npc_headcrab

Kopfkrabbe