King cobra

The king cobra, known scientifically as Ophiophagus hannah, is not a single species but a species complex native to Asia. It holds the title of the world’s longest venomous snake, averaging 3.18 to 4 meters in length, with a record of 5.85 meters, and it is also among the heaviest. Despite its common name and superficial resemblance, it belongs to its own genus, Ophiophagus, and is not a true cobra in evolutionary terms. Its range stretches from the Indian subcontinent through Southeast Asia to southern China, and while widely distributed, it is rarely encountered.

Diet

Across its habitats, individual king cobras display varied coloration, from black with white stripes to unbroken brownish grey. Following taxonomic re-evaluation, the genus is no longer considered to have only one member; differences in pattern and other traits may lead to its division into at least four distinct species, each spread across its vast geographic range. This snake primarily hunts other snakes, including members of its own species, though it occasionally preys on lizards and rodents.

It is the only snake that builds an above-ground nest for its eggs, which the female carefully gathers and guards throughout the incubation period. When threatened, it displays a characteristic warning: it spreads its neck flaps, raises its head, hisses, and may charge. It can strike over considerable distance and height, delivering a large volume of venom. Envenomation causes rapid neurotoxic and cytotoxic symptoms, requiring immediate antivenom.

Etymology

Despite its fearsome reputation, aggression toward humans usually occurs only if the snake is accidentally exposed or cornered; encounters are typically chance events. Threatened by habitat destruction, the king cobra has been listed as Vulnerable on the IUCN Red List since 2010. It is the national reptile of India and holds a prominent place in the mythology and folk traditions of India, Bangladesh, Sri Lanka, and Myanmar. In older literature, the king cobra is also called the “hamadryad.” Danish naturalist Theodore Edward Cantor gave it the scientific name Hamadryas hannah in 1836, based on four specimens: three from the Sundarbans and one from near Kolkata.

The origin of the species name hannah was not explained at the time and remains uncertain, but it may refer to Hannah Sarah Wallich, the eldest daughter of Cantor’s uncle, botanist Nathaniel Wallich, who hosted Cantor during his studies in India. The genus Ophiophagus was proposed by Günther in 1864 to replace Hamadryas, because that name was already in use for cracker butterflies. The name reflects the snake’s habit of eating other snakes.

Taxonomy

In 1945, Charles Mitchill Bogert accepted Ophiophagus hannah as the valid name, arguing it differs significantly from Naja species. It has been suggested that three additional king cobra species exist: the Sunda king cobra (O. bungarus), the Western Ghats king cobra (O. kaalinga), and the Luzon king cobra (O. salvatana). These genetic lineages are geographically isolated and adapted to specific ecological regions. In 1838, Cantor proposed the name Hamadryas ophiophagus, noting its dental features are intermediate between Naja and Bungarus.

Synonyms

In 1840, Walter Elliot proposed Naia vittata for a king cobra caught offshore near Chennai in a floating basket; this origin is disputed, as wild king cobras have never occurred near Chennai, and analysis shows the specimen resembles the northern king cobra. In 1858, Albert Günther proposed Hamadryas elaps for specimens from the Philippines and Borneo, considering both N. bungarus and N. vittata varieties of it. Naja ingens was proposed in 1882 for a specimen from near Tebing Tinggi in northern Sumatra. The earliest scientific name for the king cobra was Naja bungaroides, given by Friedrich Boie in 1828 for a juvenile from Java, but the description was insufficient, making it a nomen nudum.

Johann Georg Wagler validated the name in 1830 with a proper diagnosis and placed it in a new genus, Hoplocephalus. In 1837, Hermann Schlegel used Naja bungaroides for the Australian broad-headed snake, later reclassified into Hoplocephalus, and used Naja bungarus for the king cobra. This caused a mix-up: the name Naja/Hoplocephalus bungaroides, originally for the king cobra, became attached to the broad-headed snake and used as the type species of Hoplocephalus, while Naja bungarus was treated as a junior synonym of the king cobra (until revived for the Sunda king cobra in 2024).

This discrepancy, which violates the principle of priority, went unnoticed for nearly two centuries and was only discovered in 2024. To avoid upending the long-established names Ophiophagus hannah and Hoplocephalus bungaroides, it was decided to keep both names and designate a new, accurate type specimen for the broad-headed snake. Genetic analyses using cytochrome b and multigene data show that the king cobra branched off early from the lineage that gave rise to mambas, rather than from Naja cobras. A phylogenetic study of mitochondrial DNA revealed that specimens from Surat Thani and Nakhon Si Thammarat provinces in southern Thailand form a deeply divergent genetic clade from those in northern Thailand, which group with specimens from Myanmar and Guangdong in southern China.