The Carnivorous Leech is approximately twenty centimeters (eight inches) in length, somewhat snake-like and beige in color. The creature's head is featureless save for a round mouth bristling with sharp teeth. In Half-Life, these Leeches seem to live in fresh water, as they appear in several areas of Black Mesa which have been flooded. (In at least one case, when a room is drained, the Leeches flop harmlessly on the floor for several seconds until they die.) Although they deal relatively little damage and can be killed easily with a crowbar (for example; explosives are effective as well), they can quickly overwhelm the player when appearing in large numbers.