Tentacle



Tentacles first appear in the Black Mesa Research Facility, where three tentacle creatures are growing inside a rocket propulsion test chamber. They reappear later in the game, including appearances on the surface and in Xen.

Appearance
A large, green, segmented stalk supports a "head", which ends in a sharply pointed, bladelike appendage and features what looks like an eye. This "eye" appears to be a sensory organ, although the creature only reacts to sound and surface vibrations. Tentacles usually emanate from pits, into which they can retract when injured or in danger.

Typically several tentacles use the same pit, suggesting that they may be appendages of a larger organism. Indeed in Half-Life, after the first tentacle encounter, the player travels through the chasm the creature had occupied. The tentacle's body encountered at the bottom of the chasm is somewhat squid shaped, with three stumps that appear to have been severed. Some concept art of the tentacle, shows it to be cluster of three tentacles attached to a bulbous base, which matches that encountered in the game. Although tentacles usually come in groups or clusters of three, single tentacles are also encountered, and the number of tentacles present may reflect the size or stage of development of the base, or else a more spread-out being, with tentacles in various locales.

Behavior
In terms of behavior, tentacles aggressively target prey in the immediate vicinity of their pits. While searching for prey, they gently tap the surrounding area, but when even the quietest noise or vibration is detected, the tentacles will furiously and repeatedly strike at the location where noise or vibration was detected. When a tentacle comes in contact with prey, it will attempt to pull it into the pit, presumably where it is consumed and digested. In the game, this behaviour is witnessed firsthand by the player when a scientist is grabbed and taken, screaming, into the pit at the base of the tentacles.

In the game, tentacles cannot be destroyed with the player's arsenal, but shooting the stalk a few times will temporarily drive the creature into its burrow. Great care must be taken when moving near them, forcing the player either to silently crouch past the burrow or cause a distraction with explosives (preferably hand grenades, as those don't reveal the player's location with sound), allowing the player to sprint out of range.