Cobra means snake in Portuguese. The 'true' cobras are members of the Naja genus of snakes, of which the majority of species are found in Africa, with the remainder in Asia. Snakes of the genus of naja are some of the world's most dangerous snakes, being venomous.

The distinctive characteristic of a cobra is its hood, and snakes from other genuses than Naja that have hoods, are also commonly referred to as cobras.

King cobra

Perhaps the most famous 'cobra', the king cobra, Ophiophagus hannah, is not a member of Naja genus, and therefore not a true cobra. Ophiophagus means 'snake eater', as the king cobra's diet is of smaller snakes. 

The king cobra's large size means it can deliver very large volumes of venom, resulting an untreated human fatality rate of around 50%, and in contrast to some other cobra species, nearly all king cobra bites are 'wet' (containing venom). Despite this, the king cobra is not a threat to humans, as most bites occur to people who have sought to confront or handle the snake. In April 2016, a dangdut singer in Java, Indonesia, was killed by a king cobra, which she used as a prop during her performance. In the wild, the king cobra will typically flee humans, however, as the king cobra is a rare snake that cares for its eggs after they have been laid, a brooding snake is more likely to stand its ground. When standing its ground, the king cobra raises itself high above the ground, spreads its hood, and makes a hissing sound.

The king cobra is present all over Sumatra, including in Bukit Lawang. They can grow up to five metres in length.

Sumatran spitting cobra 

The one true cobra found in Sumatra, and in Bukit Lawang, is the Sumatran spitting cobra (also known as the equatorial spitting cobra), Naja sumatrana. Despite its name, it is also found in Malaysia, the Philippines, Thailand and Singapore. It is closely related to Naja siamensis (Indochinese spitting cobra) from Thailand, and Naja sputatrix, the Javan spitting cobra. Together the three snakes were previously considered one species, the Malayan spitting cobra, Naja sputatrix. 

Naja sumatrana is geographically variable in appearance, in Sumatra and southern Malaya appearing black, while in northern Malaya, they are light brown or yellowish. The snake grows up to 1.5 metres in length. They can spit venom, aiming for their victims eyes in order to blind them.

The Sumatran spitting cobra's venom is less likely to be deadly than that of the king cobra, but this is more than offset by the fact that it spits its venom very readily.

Sumatran spitting cobra at Bukit Lawang: