Of all the creatures found in national park Khao Sok, perhaps the most feared is the terrestrial leech. These animals carry no toxins, diseases, or bacteria, and pose no risk to hikers. However, as a result of their appearance and penchant for bloody bites, they are often misunderstood.
The common land leech is small and usually rarely more than an inch long. It lives among fallen leaves and debris and uses vibrations in the ground to sense incoming animals. It is true that leeches feed on blood. This is generally painless and often the victim is left completely unawares. To feed, the leech inserts a tiny straw-like tube. Then it injects an anticoagulant which keeps blood from clotting. It then drinks a small amount of blood. Due to the anticoagulant leech bites are known for their propensity to bleed for an extended period.