King cobra

• 1. Introduction

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  The king cobra, Ophiophagus hannah, is the longest venomous snake in the world. The longest individual on record stretched 5.85 metres. Adults usually measure between 3.18 and 4 metres, and the species also ranks among the heaviest venomous snakes. The largest known animal was captured in Thailand and measured 18 feet 4 inches.

  Despite its common name, the king cobra is not a true cobra. It belongs to its own genus, Ophiophagus, and only resembles the cobras of the genus Naja. Its home stretches from the Indian subcontinent through Southeast Asia to southern China. Even so, it is not commonly seen.

  This documentary asks a set of questions. Who was the Hannah in its scientific name, if anyone? Is the king cobra one species, or several wearing the same skin? Why does a snake that eats other snakes build a nest like a bird? And why do people in several countries treat it with something close to reverence?

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• 2. A Name and Its Mysteries

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  In 1836, the Danish naturalist Theodore Edward Cantor described four king cobra specimens and named the animal Hamadryas hannah. Three of his snakes came from the Sundarbans. The fourth came from the area around Kolkata. Cantor never explained the word hannah, and its origin has stayed uncertain for generations. One possibility is Hannah Sarah Wallich, the eldest daughter of his uncle, the botanist Nathaniel Wallich, who hosted Cantor during his studies in India. Older books often call the snake the hamadryad instead.

  The genus name did not last. In 1864, Günther proposed Ophiophagus, because the name Hamadryas had already been given to the cracker butterflies. The new word means, roughly, snake eater. In 1945, Charles Mitchill Bogert accepted Ophiophagus hannah as the valid name and argued that the snake differs significantly from the Naja cobras.

  Many other names came and went. In 1838, Cantor himself suggested Hamadryas ophiophagus and noted that the snake's teeth sit between those of Naja and Bungarus. In 1840, Walter Elliot named Naia vittata from a specimen said to have been found floating offshore near Chennai in a basket. That origin is disputed, because wild king cobras have never lived near Chennai. Analysis suggests the animal was closer to the northern king cobra.

  The oldest name of all, Naja bungaroides, came from Friedrich Boie in 1828. He based it on a juvenile snake from Java, but his description was improperly done, so the name counted as a nomen nudum, a name without a valid description. Johann Georg Wagler validated it in 1830 and proposed the genus Hoplocephalus for it.

  Then came a mix-up. In 1837, Hermann Schlegel used bungaroides for the Australian broad-headed snake, and the name drifted away from the king cobra and stuck to the Australian animal. This broke the rule that the oldest valid name wins, and nobody noticed for nearly two centuries. Because Ophiophagus hannah and Hoplocephalus bungaroides were so entrenched, researchers kept both names and chose a new, accurate type specimen for the broad-headed snake. The discrepancy came to light only in 2024, the same year the old name bungarus was revived for a proposed species.

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• 3. One Species or Four

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  The Sunda king cobra, Ophiophagus bungarus, is one of three additional species that researchers have suggested. The others are the Western Ghats king cobra, Ophiophagus kaalinga, and the Luzon king cobra, Ophiophagus salvatana. These are distinct genetic lineages. Each is geographically isolated and adapted to its own ecological region.

  After this re-evaluation, the king cobra is no longer the only member of its genus. It is now treated as a species complex. Differences in pattern and other traits may eventually split the genus into at least four species. Colouring alone hints at the diversity. Some animals are black with white stripes, while others are an unbroken brownish grey.

  Deep inside the family tree, the king cobra is an early offshoot of the lineage that produced the mambas, rather than the Naja cobras. Genetic work in Thailand adds detail. Snakes from Surat Thani and Nakhon Si Thammarat provinces in the south form a deeply divergent group. Snakes from the north of the country grouped instead with specimens from Myanmar and Guangdong in southern China.

  The range itself is vast. The snake occurs at elevations of 2000 metres, from the Terai in India and southern Nepal to the Brahmaputra River basin in Bhutan and northeast India. It also lives in Bangladesh, Myanmar, Cambodia, Thailand, Laos, Vietnam, Malaysia, Singapore, Indonesia and the Philippines. Within India it has been recorded in Garhwal and Kumaon, across northeast states such as Assam and Mizoram, and in the Eastern and Western Ghats. It also occurs on Baratang Island in the Great Andaman chain.

  The far western edge is the most puzzling. Records near Lahore and Palanpur were once blamed on snake charmers or on transport along rivers. They are now more likely seen as natural populations, though it remains uncertain whether any king cobras still persist there.

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• 4. Body and Growl

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  Olive green skin, banded in black and white, defines the adult king cobra. The bands converge toward the head, which is covered by 15 drab, black-edged shields. The muzzle is rounded, the tongue is black, and the large eyes have a golden iris with round pupils. The snake has two fangs and three to five maxillary teeth in the upper jaw, and two rows of teeth in the lower. Its oval hood is covered in smooth olive scales, with two black spots between the lowest pair.

  Juveniles look quite different. They are black, with white, yellow or buff chevron-shaped bars that point toward the head. Males are larger and paler than females, especially in the breeding season. Males captured in Kerala reached 3.75 metres and 10 kilograms. Captured females topped out at 2.75 metres and 5 kilograms. Compared with other cobras, the king cobra is bigger, with a narrower and longer stripe on the neck.

  In Singapore, wild king cobras seemed placid, yet they reared up and struck when cornered. The snake is not considered aggressive and normally slips away from people. When alarmed, it lifts the front of its body, spreads the hood, shows its fangs and hisses loudly. Sudden movements or objects approaching closely can irritate it. A raised snake can still lunge a long way forward, so people often misjudge the safe distance, and it can bite several times in one attack.

  The sound it makes is unusual. Most snake hisses spread across roughly 3,000 to 13,000 hertz, with a dominant pitch near 7,500. King cobra growls contain only frequencies below 2,500 hertz, with a dominant pitch near 600, much closer to a human voice. Anatomical study found tracheal diverticula, which are side pockets off the windpipe that act as low-frequency resonating chambers. The rat snake, one of the king cobra's prey, has them too and can make a similar growl.

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• 5. The Snake Hunter

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  A forked tongue is the king cobra's first hunting tool. It collects scent particles and carries them to the Jacobson's organ, a sensory receptor in the roof of the mouth. With that chemical sense, the snake can follow odour trails. This is how it tracks the Malabar pit viper and the hump-nosed pit viper.

  The menu reads like a directory of Asian snakes. It includes the Indian cobra, the banded krait, the Oriental rat snake, reticulated pythons, the green whip snake, the Himalayan keelback, the banded wolf snake and Blyth's reticulated snake. Lizards, including varanids, are also eaten. In Singapore, one king cobra was observed swallowing a clouded monitor. As an apex predator, it dominates all other snakes except large pythons.

  When food is scarce, it turns to other small vertebrates, such as birds. Constriction is occasionally used, but this is uncommon. Usually it envenomates its prey first and then swallows it whole. Flexible jaws let it take prey much larger than its own head. It hunts mainly by day and is considered diurnal, though it has rarely been seen active at night.

  Because of a slow metabolic rate, a large meal can sustain the snake for many months before it needs another.

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• 6. The Leaf Nest

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  From late March to late May, a female king cobra begins building. Using dry leaf litter, she makes the only above-ground nest built by any snake. Most nests sit at the base of a tree. They stand up to 55 centimetres high at the centre and 140 centimetres wide at the base. Several layers form the structure, and most have a single chamber where she lays her eggs.

  The female is gravid for 50 to 59 days. A clutch holds 7 to 43 eggs, and between 6 and 38 of them hatch after 66 to 105 days. Nest temperature is not steady. Depending on elevation, it swings between 13.5 and 37.4 degrees Celsius. Females stay near their nests for anywhere from two to 77 days, and they defend the eggs aggressively, attacking intruders rapidly.

  The hatchlings measure 37.5 to 58.5 centimetres and weigh 9 to 38 grams. They are alert and nervous, and highly aggressive if disturbed. Their venom is as potent as an adult's. They may be brightly marked, though these colours often fade as they mature.

  Some king cobras can also reproduce without a mate. The species has shown facultative parthenogenesis, meaning a female can produce offspring on her own when conditions allow. The mechanism appears to be a variation of meiosis called terminal fusion automixis. In the wild, a king cobra lives about 20 years on average.

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• 7. Anatomy of a Bite

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  Up to 420 milligrams of dry venom can leave a king cobra in a single bite, and the overall range is 400 to 600 milligrams. For research, up to one gram has been obtained by milking. In mice, the dose that kills is 1.28 milligrams per kilogram by intravenous injection and 1.5 to 1.7 by subcutaneous injection.

  The postorbital venom glands make a mixture built mainly from three-finger toxins and snake venom metalloproteinases. Among the three-finger toxins, alpha-neurotoxins are the most abundant and most lethal. Cytotoxins, which damage cells, and beta-cardiotoxins also act. Cytotoxicity varies with the snake's age and locality. Heart and kidney damage are not widely seen in patients, probably because those toxins are scarce.

  The metalloproteinases make up 11.9 to 24.4 percent of the venom proteins. Most cobras carry less than 1 percent. These proteins usually cause vessel damage and bleeding in viper bites. In the king cobra, the haemorrhagins isolated so far affect rabbits and hares but barely touch mice. Their role in human cases is not well studied. A minor protein called ohanin, found only in this species, causes reduced movement and heightened pain sensitivity in mice. It is believed to add to nervous system effects in victims.

  A bite is an immediate medical emergency for people or domestic animals, and without treatment death can come in as little as 30 minutes. The skin darkens, swells and hurts. In severe cases, tissue dies and may require amputation. Blurred vision, vertigo and drowsiness follow as venom attacks the central nervous system, then paralysis. Untreated, the victim can suffer cardiovascular collapse and coma, and death comes through respiratory failure and other organ failures.

  Treatment depends on antivenom. India's Haffkine Institute and King Institute of Preventive Medicine and Research make a polyvalent antivenom from horses. The Thai Red Cross Society makes a polyvalent antivenom that can neutralise the venom effectively. One patient treated with the right antivenom and hospital care recovered and was discharged after 10 days. In India and Thailand, a blend of turmeric and other herbs is used in folk medicine, but there is no clinical evidence that it works.

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• 8. Law and Legend

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  The International Union for Conservation of Nature has listed the king cobra as Vulnerable since 2010. In Southeast Asia, the greatest threat is habitat destruction from deforestation and expanding farmland. Wildlife smuggling and poaching add to the pressure. Poached animals are sold as bushmeat, turned into snake leather, or used in traditional Chinese medicine.

  The snake is listed in CITES Appendix II and protected in China and Vietnam. In India, it falls under Schedule II of the Wildlife Protection Act, 1972, and killing one can bring up to six years in prison. In the Philippines, where it is called banakon, Republic Act No. 9147 protects threatened species. The maximum penalty is two years in prison and a fine of 20,000 pesos, with exceptions such as indigenous subsistence hunting or immediate threats to human life.

  The animal holds a prominent place in the mythology and folklore of India, Bangladesh, Sri Lanka and Myanmar, and it is India's national reptile. In Myanmar, a ritual pairs a king cobra with a female snake charmer. She is a priestess, usually tattooed with three pictograms, who kisses the snake on the top of its head at the end. Members of the Pakokku clan tattoo their upper bodies with ink mixed with cobra venom. They believe this weekly inoculation protects them, though no scientific evidence supports it.

  A myth in India holds that the king cobra has exceptional memory. According to the story, the face of its killer stays imprinted in the snake's eyes, and the dead snake's partner uses that image to hunt the killer down. Because of this belief, the head of a killed cobra is often crushed or burned to destroy the eyes.

  In Bangkok's Bang Khun Thian district, beside Rama II Road, stands a shrine built after the nest and young of a large female king cobra were destroyed during road construction. It honours a female spirit associated with the cobra. A nearby shrine honours a male spirit, believed to be her mate, who is said to have come later to meditate and live as an ascetic in dedication to her and her offspring. Locals still believe the overgrown land behind and beneath the shrines shelters several large king cobras.

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