The King Cobra is a large and powerful snake, averaging 3.6-4 m (12-13 feet) in length and typically weighing about 6 kg (13.2 lb). The record-sized wild cobra was shot in the Nakhon Si Thammarat Mountains of south Thailand and was 5.6 m (18.5 ft). An even larger cobra was kept captive at the London Zoo and grew to 5.7 m (18.8 ft) before being euthanized upon the outbreak of World War II. The skin is either olive-green, tan, or black and it has faint, pale yellow cross bands down the length of the body. The belly is cream or pale yellow, and the scales are smooth. The head of a mature snake can be quite massive and bulky in appearance, though like all snakes, they can expand their jaws to swallow large prey items. It has proteroglyph dentition, meaning it has two short, fixed fangs in the front of the mouth which channel venom into the prey like hypodermic needles. The male is larger and thicker than the female. The average lifespan of a King Cobra is about 20 years.