The king cobra (Ophiophagus hannah) is a
venomoussnakeendemic to
Asia. The
sole member of the genus Ophiophagus, it is not taxonomically a
true cobra, despite its common name and some resemblance. With an average length of 3.18 to 4 m (10.4 to 13.1 ft) and a record length of 5.85 m (19.2 ft),[2] it is the world's longest venomous snake. The species has diversified colouration across
habitats, from black with white stripes to unbroken brownish grey. The king cobra is widely distributed albeit not commonly seen, with a range spanning from the
Indian Subcontinent through
Southeastern Asia to
Southern China. It preys chiefly on other snakes, including
those of its own kind. This is the only ophidian that constructs an above-ground nest for its eggs, which are purposefully and meticulously gathered and protected by the female throughout the
incubation period.[3]
The
threat display of this
elapid includes spreading its neck-flap, raising its head upright, making eye contact, puffing, hissing and occasionally charging. Given the size of the snake, it is capable of striking at a considerable range and height, sometimes sustaining a bite.
Envenomation from this species is
medically significant and may result in a rapid fatality unless
antivenom is administered in time. Despite the species' fearsome reputation, aggression toward humans usually only arises from an individual inadvertently exposing itself or being cornered.
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.[4]Naja bungarus was proposed by
Hermann Schlegel in 1837 who described a king cobra
zoological specimen from
Java.[5]
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.[6]Naia vittata proposed by
Walter Elliot in 1840 was a king cobra caught offshore near
Chennai that was floating in a basket.[7]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.[8]
The
genusOphiophagus was proposed by Günther in 1864.[9] The name is derived from its propensity to eat snakes.[10]
The king cobra's skin is olive green with black and white bands on the trunk that converge to the head. The head is covered by 15 drab coloured and black edged shields. The muzzle is rounded, and the tongue black. It has two fangs and 3–5 maxillar teeth in the upper jaw, and two rows of teeth in the lower jaw. The nostrils are between two shields. The large eyes have a golden iris and round pupils. Its hood is oval shaped and covered with olive green smooth
scales and two black spots between the two lowest scales. Its cylindrical tail is yellowish green above and marked with black.[4]
It has a pair of large
occipital scales on top of the head, 17 to 19 rows of smooth oblique scales on the neck, and 15 rows on the body. Juveniles are black with
chevron shaped white, yellow or buff bars that point towards the head.[16]
Adult king cobras are 3.18 to 4 m (10.4 to 13.1 ft) long. The longest known individual measured 5.85 m (19.2 ft).[2][17] Ventral scales are uniformly oval shaped. Dorsal scales are placed in an oblique arrangement.[18]
The king cobra is
sexually dimorphic, with males being larger and paler in particular during the breeding season. Males captured in Kerala measured up to 3.75 m (12.3 ft) and weighed up to 10 kg (22 lb). Females captured had a maximum length of 2.75 m (9 ft 0 in) and a weight of 5 kg (11 lb).[19]
The largest known king cobra was 5.59 m (18 ft 4 in) long and captured in Thailand.[20]
It differs from other cobra species by size and hood. It is larger, has a narrower and longer stripe on the neck.[21]
Distribution and habitat
The king cobra has a wide distribution in South and Southeast Asia. It occurs up to an elevation of 2,000 m (6,600 ft) from the
Terai in India and southern Nepal to the
Brahmaputra River basin in Bhutan and northeast India, Bangladesh and to Myanmar, southern China, Cambodia, Thailand, Laos, Vietnam, Malaysia, Singapore, Indonesia and the Philippines.[1]
Like other snakes, a king cobra receives chemical information via its
forked tongue, which picks up scent particles and transfers them to a sensory receptor (
Jacobson's organ) located in the roof of its mouth.[2] When it detects the scent of prey, it flicks its tongue to gauge the prey's location, with the twin forks of the tongue acting in stereo. It senses earth-borne
vibration and detects moving prey almost 100 m (330 ft) away.[citation needed]
Following
envenomation, it swallows its prey whole. Because of its flexible jaws, it can swallow prey much larger than its head. It is considered
diurnal because it hunts during the day, but has also been seen at night, rarely.[2]
The king cobra is not considered aggressive.[36] It usually avoids humans and slinks off when disturbed, but is known to aggressively defend incubating eggs and attack intruders rapidly. When alarmed, it raises the front part of its body, extends the
hood, shows the
fangs and hisses loudly.[32][37]
Wild king cobras encountered in Singapore appeared to be placid, but reared up and struck in self defense when cornered.[38]
The king cobra can be easily irritated by closely approaching objects or sudden movements. When raising its body, the king cobra can still move forward to strike with a long distance, and people may misjudge the safe zone. It can deliver multiple bites in a single attack.[39]
Growling hiss
The hiss of the king cobra is a much lower pitch than many other snakes and many people thus liken its call to a "growl" rather than a hiss. While the hisses of most snakes are of a broad-frequency span ranging from roughly 3,000 to 13,000
Hz with a dominant frequency near 7,500 Hz, king cobra growls consist solely of frequencies below 2,500 Hz, with a dominant frequency near 600 Hz, a much lower-sounding frequency closer to that of a human voice. Comparative anatomical morphometric analysis has led to a discovery of tracheal
diverticula that function as low-frequency resonating chambers in king cobra and its prey, the rat snake, both of which can make similar growls.[40]
Reproduction
The female is
gravid for 50 to 59 days.[17]
The king cobra is the only snake that builds a nest using dry
leaf litter, starting from late March to late May.[41] Most nests are located at the base of trees, are up to 55 cm (22 in) high in the centre and 140 cm (55 in) wide at the base. They consist of several layers and have mostly one chamber, into which the female lays eggs.[42]
Clutch size ranges from 7 to 43 eggs, with 6 to 38 eggs hatching after
incubation periods of 66 to 105 days. Temperature inside nests is not steady but varies depending on elevation from 13.5 to 37.4 °C (56.3 to 99.3 °F). Females stay by their nests between two and 77 days. Hatchlings are between 37.5 and 58.5 cm (14.8 and 23.0 in) long and weigh 9 to 38 g (0.32 to 1.34 oz).[41]
The venom of hatchlings is as potent as that of the adults. They may be brightly marked, but these colours often fade as they mature. They are alert and nervous, being highly aggressive if disturbed.[21]
The average lifespan of a wild king cobra is about 20 years.[43]
Of all the 3FTx,
alpha-neurotoxins are the predominant and most lethal components when
cytotoxins and
beta-cardiotoxins also exhibit toxicological activities.[46][47][48] It is reported that
cytotoxicity of its venom varies significantly, depending upon the age and locality of an individual.[49] Clinical
cardiotoxicity is not widely observed, nor is
nephrotoxicity present among patients bitten by this species, presumably due to the low abundance of the toxins.[39]
SVMPs are the second most protein family isolated from the king cobra's venom, accounting from 11.9% to 24.4% of total venom proteins.[50][51][52] The abundance is much higher than that of most
cobras which is usually less than 1%.[53] This protein family includes principal toxins responsible for
vasculature damage and interference with
haemostasis, contributing to
bleeding and
coagulopathy caused by envenomation of
vipers. While there are such haemorrhagins isolated from the king cobra's venom, they only induce species-sensitive haemorrhagic and lethal activities on rabbits and hares, but with minimal effects on mice.[54] Clinical pathophysiology of the king cobra's SVMPs has yet to be well studied, although its substantial quantity suggests involvement in tissue damage and necrosis as a result of inflammatory and proteolytic activities, which are instrumental for foraging and digestive purposes.[54][39]
Ohanin, a minor vespryn protein component specific to this species, causes
hypolocomotion and
hyperalgesia in experimental mice. It is believed that it contributes to neurotoxicity on the
central nervous system of the victim.[55]
Clinical Management
King cobra's envenomation may result in a rapid fatality, as soon as 30 minutes following a bite.[39][56] Local symptoms include dusky discolouration of skin,
edema and pain; in severe cases swelling extends proximally with
necrosis and tissue sloughing that may require amputation.[39] Onset of general symptoms follows while the venom is targeting the victim's
central nervous system, resulting in blurred vision,
vertigo,
drowsiness, and eventually
paralysis. If not treated promptly, it may progress to
cardiovascular collapse and subsequently
coma. Death soon follows due to
respiratory failure.[39]
Polyvalent
antivenom of
equine origin is produced by
Haffkine Institute and
King Institute of Preventive Medicine and Research in India.[57]
A polyvalent antivenom produced by the Thai
Red Cross Society can effectively neutralise venom of the king cobra.[58] In Thailand, a
concoction of
turmericroot has been clinically shown to create a strong resilience against the venom of the king cobra when ingested.[59][60] Proper and immediate treatments are critical to avoid death. Successful precedents include a client who recovered and was discharged in 10 days after being treated by accurate antivenom and
inpatient care.[56]
The king cobra is listed in
CITES Appendix II. It is protected in China and Vietnam.[1]
In India, it is placed under Schedule II of
Wildlife Protection Act, 1972. Killing a king cobra is punished with imprisonment of up to six years.[66] In the
Philippines, king cobras (locally known as banakon) are included under the list of threatened species in the country. It is protected under the Wildlife Resources Conservation and Protection Act (Republic Act No. 9147), which criminalises the killing, trade, and consumption of threatened species with certain exceptions (like indigenous subsistence hunting or immediate threats to human life), with a maximum penalty of two years imprisonment and a fine of
₱20,000.[67][68][69]
Cultural significance
The king cobra has an eminent position in the
mythology and
folklore of India, Bangladesh, Sri Lanka and Myanmar.[70]
A ritual in Myanmar involves a king cobra and a female snake charmer. The charmer is a priestess who is usually tattooed with three pictograms and kisses the snake on the top of its head at the end of the ritual.[71]
Members of the
Pakokku clan tattoo themselves with ink mixed with cobra venom on their upper bodies in a weekly inoculation that they believe would
protect them from the snake, though no scientific evidence supports this.[35][72]
It is regarded as the national reptile of India.[73]
^Lillywhite, Harvey B. (2014). How Snakes Work: Structure, Function and Behavior of the World's Snakes. New York City: Oxford University Press. p. 241.
ISBN9780195380378.
^Smith, M. A. (1943).
"Naja hannah. Hamadryad, King Cobra". The Fauna of British India, Ceylon and Burma, including the whole of the Indo-Chinese Subregion. Vol. Reptilia and Amphibia. III. – Serpentes. London: Taylor and Francis. pp. 436–438.
^
abChanhome, L.; Cox, M. J.; Vasaruchapong, T.; Chaiyabutr, N.; Sitprija, V. (2011). "Characterization of venomous snakes of Thailand". Asian Biomedicine 5 (3): 311–328.
^
abO'Shea, M. (2008). Venomous snakes of the world. London, Cape Town, Sydney, Auckland: Bloomsbury Publishing Plc.
ISBN9781847730862.
^Singh, A.; Joshi, R. (2016). "A first record of the King Cobra Ophiophagus hannah (Reptilia: Squamata: Elapidae) nest from Garhwal Himalaya, northern India". Zoo's Print. 31: 9–11.
^
abcWallach, V.; Williams, K.L.; Boundy, J. (2014). Snakes of the world: A catalogue of living and extinct species. Florida: CRC Press, Taylor and Francis Group. pp. 507–508.
ISBN9781482208481.
^Kurniawan, A.; Lee, G.; bin Tohed, N.; Low, M.-R. (2018).
"King cobra feeding on a monitor lizard at night"(PDF). Singapore Biodiversity Records. 2018: 63.
Archived(PDF) from the original on 16 October 2019. Retrieved 16 October 2019.
^
abCoborn, J. (1991). The Atlas of Snakes of the World. TFH Publications. pp. 30, 452.
ISBN978-0-86622-749-0.
^Tweedie, M. W. F. (1983). The Snakes of Malaya. Singapore: Singapore National Printers Ltd. p. 142.
OCLC686366097.
^Greene, H. W. (1997).
"Antipredator tactics of snakes". Snakes: The Evolution of Mystery in Nature. California, USA: University of California Press. pp. 103–111.
ISBN0-520-22487-6.
Archived from the original on 10 February 2023. Retrieved 4 October 2020.
^
abcdefDavidson, T.
"Immediate First Aid". University of California, San Diego.
Archived from the original on 30 June 2010. Retrieved 24 September 2011.
^Young, B. A. (1991). "Morphological basis of "growling" in the king cobra, Ophiophagus hannah". Journal of Experimental Zoology. 260 (3): 275–287.
doi:
10.1002/jez.1402600302.
PMID1744612.
^Chang, L.-S.; Liou, J.-C.; Lin, S.-R.; Huang, H.-B. (2002). "Purification and characterization of a neurotoxin from the venom of Ophiophagus hannah (king cobra)". Biochemical and Biophysical Research Communications. 294 (3): 574–578.
doi:
10.1016/S0006-291X(02)00518-1.
PMID12056805.
^He, Y. Y.; Lee, W. H.; Zhang, Y. (2004). "Cloning and purification of alpha-neurotoxins from king cobra (Ophiophagus hannah)". Toxicon. 44 (3): 295–303.
doi:
10.1016/j.toxicon.2004.06.003.
PMID15302536.
^Pung, Y. F.; Kumar, S. V.; Rajagopalan, N.; Fry, B. G.; Kumar, P. P.; Kini, R. M. (2006). "Ohanin, a novel protein from king cobra venom: Its cDNA and genomic organization". Gene. 371 (2): 246–256.
doi:
10.1016/j.gene.2005.12.002.
PMID16472942.
^
abTin-Myint; Rai-Mra; Maung-Chit; Tun-Pe; Warrell, D. (1991). "Bites by the king cobra (Ophiophagus hannah) in Myanmar: Successful treatment of severe neurotoxic envenoming". The Quarterly Journal of Medicine. 80 (293): 751–762.
doi:
10.1093/oxfordjournals.qjmed.a068624.
PMID1754675.
^Ernst, C. H.; Evelyn, M. (2011).
"Treatment of envenomation by reptiles". Venomous Reptiles of the United States, Canada, and Northern Mexico. Vol. 1: Heloderma, Micruroides, Micrurus, Pelamis, Agkistrodon, Sistrurus. Baltimore: Johns Hopkins University Press. pp. 33–46.
ISBN978-0-8018-9875-4.
^Salama, R.; Sattayasai, J.; Gande, A. K.; Sattayasai, N.; Davis, M.; Lattmann, E. (2012). "Identification and evaluation of agents isolated from traditionally used herbs against Ophiophagus hannah venom". Drug Discoveries & Therapeutics. 6 (1): 18–23.
^
abSéan Thomas & Eugene Griessel – Dec 1999.
"LD50 (Archived)". Archived from
the original on 1 February 2012.{{
cite web}}: CS1 maint: numeric names: authors list (
link)
^Ganthavorn, S. (1969). "Toxicities of Thailand snake venoms and neutralization capacity of antivenin". Toxicon. 7 (3): 239–241.
doi:
10.1016/0041-0101(69)90012-9.
PMID5358069.