You may have heard that the king cobra is a true cobra, but scientists say it is not. It differs from the Naja cobras, which are the true cobras, in several body features, and genetic work links it more closely to mambas. The scientist Theodore Cantor first described the king cobra in 1836, under the name Hamadryas hannah, and in 1864 the scientist Günther proposed the genus name Ophiophagus, which means snake-eater. Like many other venomous snakes, the king cobra belongs to a family called Elapidae.
The name Ophiophagus fits the way a king cobra feeds, because its diet is fairly specialized and is mainly other snakes, such as Asian rat snakes and pythons up to about 10 feet long. Some king cobras prefer one kind of snake and refuse to eat any other, and in general they prefer smooth-scaled snakes over snakes with keeled scales. You may have read that king cobras eat only snakes. In fact, they mostly eat snakes, but they will also eat lizards, eggs and small mammals, so the name describes the usual meal rather than every meal.
How do scientists learn where a king cobra goes? In Thailand they implant radio transmitters in the snakes and find each one by triangulation, which means locating it from the angles of the signals. In one study in northeast Thailand, scientists tracked seven king cobras for an average of about 650 days. Tracking has shown that king cobras hunt by day and can travel long distances to track their prey over a long time. They spend almost a quarter of their time up in trees or bushes, and they often stay near streams, where the temperature and the wet air stay steady.
Venom is made in a venom gland behind the eye. A king cobra's fangs are fixed to its upper jaw, so they have to be short, and a small muscle pushes the venom through the hollow fangs. The venom has neurotoxins, which are poisons that act on the nervous system.
A king cobra can spread a hood on its neck to look bigger. Its hiss is low enough to sound like a dog's growl, and it makes that sound with tiny holes in its windpipe while its lung makes the sound deeper. Snake charmers do not really hypnotize cobras with their flute music.
The king cobra is the only snake that builds a nest for its eggs. A mother pulls leaves and plants into a pile with her body. The nest has a lower chamber for the eggs and an upper chamber where the female stays. Why she stays is not known for sure: she may protect the nest, or she may help keep it at the right temperature.
A female lays about 21 to 40 eggs, which take about 60 to 90 days to hatch. Just before they hatch, the mother leaves the nest, and each baby is about 13 inches long.
As of November 2026, the IUCN Red List lists the king cobra as Vulnerable. Cutting down forests in Southeast Asia has destroyed the homes of many of them.
Words to know
- triangulation: locating by angles
- Naja: true cobras
- specialized: narrow, focused
- chamber: small room
- neurotoxins: nerve poisons
