The king cobra (Ophiophagus hannah) is a venomous snake species of elapids endemic to jungles in Southern and Southeast Asia. The sole member of the genus Ophiophagus, it is distinguishable from other cobras, most noticeably by its size and neck patterns. The king cobra is the world's longest venomous snake, with an average length of 3.18 to 4 m (10.4 to 13.1 ft),[2] reaching a maximum of 5.85 m (19.2 ft).[3] Its skin colour varies across the habitats, from black with white stripes to unbroken brownish grey. It preys chiefly on other snakes, including its own species. Unlike other snakes, it rarely hunts other vertebrates, such as rodents and lizards.
Like most cobras and mambas, the king cobra's threat display includes spreading its neck-flap, raising its head upright, puffing, and hissing. Despite its fearsome reputation, the king cobra avoids confrontation with humans whenever possible. When provoked, however, it is capable of striking a target at long range and well above the ground. Rather than biting and retreating, it may sustain its bite and inject a large quantity of venom, which is a medical emergency.[4][5]
Regarded as the national reptile of India,[6] this species has an eminent position in mythology and folk traditions of India, Sri Lanka and Myanmar.[7][8] Threatened by habitat destruction, the king cobra has been listed as Vulnerable on the IUCN Red List since 2010.[1]
The king cobra is also referred to by the common name "hamadryad", especially in older literature. Hamadryas hannah was the scientific name used by Danish naturalist Theodore Edward Cantor in 1836 who described four king cobra specimens, three captured in the Sundarbans and one in the vicinity of Kolkata.[9]Naja bungarus was proposed by Hermann Schlegel in 1837 who described a king cobra zoological specimen from Java.[10] In 1838, Cantor proposed the name Hamadryas ophiophagus for the king cobra and explained that it has dental features intermediate between the genera Naja and Bungarus.[11]Naia vittata proposed by Walter Elliot in 1840 was a king cobra caught offshore near Chennai that was floating in a basket.[12]Hamadryas elaps proposed by Albert Günther in 1858 were king cobra specimens from the Philippines and Borneo. Günther considered both N. bungarus and N. vittata a variety of H. elaps.[13]The genus Ophiophagus was proposed by Günther in 1864.[14] The name is derived from its propensity to eat snakes.[15]
Naja ingens proposed by Alexander Willem Michiel van Hasselt in 1882 was a king cobra captured near Tebing Tinggi in northern Sumatra.[16]
Ophiophagus hannah was accepted as the valid name for the king cobra by Charles Mitchill Bogert in 1945 who argued that it differs significantly from Naja species.[17]A genetic analysis using cytochrome b,[18] and a multigene analysis showed that the king cobra was an early offshoot of a genetic lineage giving rise to the mambas, rather than the Naja cobras.[19]