Leech

"I, eh, hope you like leeches."

- The Fisherman

The Leech, also known as "Carnivorous Leech" or "Hagworm", is an aquatic creature from Xen. Leeches appear as small, fish-like creatures that bear some resemblance to terrestrial leeches. They are usually white in color with yellowish-stripes.

During the Resonance Cascade, leeches were teleported to Earth, infested the oceans and seem to have endangered or caused the extinction of most terrestrial sea creatures.

Appearances


Leeches make their first appearance in Half-Life in some of the flooded sections of the Black Mesa Research Facility after the Resonance Cascade. In addition to being teleported to Earth, they were kept in the bio-dome and aquatic lab sectors for study.

Leeches also make appearances during the events of Half-Life: Opposing Force. Adrian Shephard killed most of the leeches that were kept for study.

In Half-Life 2, they attack Gordon Freeman in a swarm (an attack similar to that of the terrestrial piranha) if he ventures too far into the ocean.

Behavior
Leeches tend to behave much like terrestrial piranha. They swim in schools searching for prey. Once they find a suitable food source, they will tear the prey into pieces, swarming over the victim.

In Half-Life 2, it is theorized that they feed off of fish or other aquatic animals in the ocean. In Half-Life, it appears that there was no viable food source, which may have caused them to be cannibalistic at times.

Minor differences
In Half-Life, the leeches were relatively annoying, but never anything more than that. In Half-Life 2, they drain the players health in a matter of seconds. This may be due to the fact that in Half-life 2, they are in a more natural habitat (the sea).

Leeches as food
In Half-Life 2: Lost Coast it is revealed that, since ocean fish are now very rare (or extinct), the human occupants of coastal areas catch and eat leeches instead. It is highly probable that leeches now act as a common food source to humans and Vortigaunts.

Behind the scenes

 * The Leech appears to be based on "Medical Leech" from Earth.
 * The Ichthyosaur was originally intended to fulfill the role of keeping the player from venturing too far into the ocean.

Trivia

 * Leeches can be killed in Half-Life, but not in Half-Life 2.

List of appearances

 * N/A
 * Half-Life
 * Half-Life: Opposing Force
 * Half-Life 2
 * Half-Life 2: Raising the Bar
 * Half-Life 2: Lost Coast