Moorkhan

The Indian cobra (''Naja naja /na''dʒa nadʒa/), also known commonly as the spectacled cobra, Asian cobra, or binocellate cobra, is a species of cobra, a venomous snake in the family Elapidae. The species is native to the Indian subcontinent, and is a member of the " big four" species that are responsible for the most snakebite cases in India.

The Indian cobra is revered in Hindu mythology and culture, and is often seen with snake charmers. It is a protected species under the '' Indian Wildlife Protection Act'' (1972).

Taxonomy

The generic name and the specific epithet ''naja'' is a Latinisation of the Sanskrit word () meaning "cobra".

The Indian cobra is classified under the genus ''Naja'' of the family Elapidae. The genus was first described by Josephus Nicolaus Laurenti in 1768. The species ''Naja naja'' was first described by the Swedish physician, zoologist, and botanist Carl Linnaeus in 1758. The genus ''Naja'' was split into several subgenera based on various factors, including morphology, diet, and habitat. ''Naja naja'' is part of the subgenus ''Naja'', along with all the other species of Asiatic cobras, including ''Naja kaouthia'', ''Naja siamensis'', ''Naja sputatrix'', and the rest.

''Naja naja'' is considered to be the prototypical cobra species within the subgenus ''Naja'', and within the entire genus ''Naja''. All Asiatic species of ''Naja'' were considered conspecific with ''Naja naja'' until the 1990s, often as subspecies thereof. Many of the subspecies were later found to be artificial or composites. This causes much potential confusion when interpreting older literature.

Description

The Indian cobra is a moderately sized, heavy-bodied species. This cobra species can easily be identified by its relatively large hood, which it expands when threatened.

Many specimens exhibit a hood mark. This hood mark is located at the rear (dorsal surface) of the Indian cobra's hood. When the hood mark is present, it consists of two circular ocelli patterns connected by a curved line, evoking the image of spectacles.

This species has a head that is elliptical, depressed, and very slightly distinct from the neck. The snout is short and rounded with large nostrils. The eyes are medium in size and the pupils are round. The majority of adult specimens range from in length. Some specimens, particularly those from Sri Lanka, may grow to lengths of , but this is relatively uncommon.

The Indian cobra varies tremendously in colour and pattern throughout its range. The ventral scales or the underside colouration of this species can be grey, yellow, tan, brown, reddish or black. Dorsal scales of the Indian cobra may have a hood mark or colour patterns. The most common visible pattern is a posteriorly convex light band at the level of the 20th to 25th ventrals. Salt-and-pepper speckles, especially in adult specimens, are seen on the dorsal scales.

Specimens, particularly those found in Sri Lanka, may exhibit poorly defined banding on the dorsum. Ontogenetic colour change is frequently observed in specimens in the northwestern parts of their geographic range (southern Pakistan and northwestern India). In southern Pakistan, juvenile specimens may be grey in colour and may or may not have a hood mark. Adults on the other hand are typically uniformly black in colour on top ( melanistic), while the underside, outside the throat region, is usually light.

Patterns on the throat and ventral scales are also variable in this species. The majority of specimens exhibit a light throat area followed by dark banding, which can be 4–7 ventral scales wide. Adult specimens also often exhibit a significant amount of mottling on the throat and on the venter, which makes patterns on this species less clear relative to patterns seen in other species of cobra. With the exception of specimens from the northwest, there is often a pair of lateral spots on the throat where the ventral and dorsal scales meet. The positioning of these spots varies, with northwestern specimens having the spots positioned more anterior, while specimens from elsewhere in their range are more posterior.

Scalation

Dorsal scales are smooth and strongly oblique. Midbody scales are in 23 rows (21–25), with 171–197 ventrals. There are 48–75 divided subcaudals and the anal shield is single. There are seven upper labials (3rd the largest and in contact with the nasal anteriorly, 3rd and 4th in contact with the eye) and 9-10 lower labials (small angular cuneate scale present between 4th and 5th lower labial), as well as one preocular in contact with internasals, and three postoculars. Temporals are 2 + 3.

Similar species

The Oriental rat snake ''Ptyas mucosa'' is often mistaken for the Indian cobra; however, this snake is much longer and can easily be distinguished by the more prominent ridged appearance of its body. Other snakes that resemble ''Naja naja'' are the banded racer '' Argyrogena fasciolata'' and the Indian smooth snake '' Wallophis brachyura''. Also, the monocled cobra (''Naja kaouthia'') may be confused with ''Naja naja''; however, the monocled cobra has an O-shaped pattern on the back of the hood, while the Indian cobra has a spectacles-shaped pattern on its hood. Confusions may exist with Caspian cobra (''Naja oxiana''), as some Indian cobra specimens without a hood mark are sometimes confused with ''N. oxiana'', where these two species coexist in Pakistan and Afghanistan. Although some Caspian cobra specimens can be quite dark, they are never fully black like the Indian cobra. ''N. oxiana'' normally has several dark bands under the throat, whereas in the black phase of ''N. naja'' from Pakistan, almost the entire throat is black.

Distribution

The Indian cobra is native to the Indian subcontinent and can be found throughout India, Pakistan, Sri Lanka, Bangladesh, and southern Nepal. In India, it may or may not occur in the state of Assam, some parts of Kashmir, and it does not occur at high altitudes of over and in extreme desert regions. In Pakistan, it is absent in most of Balochistan province, parts of Khyber Pakhtunkhwa Province, desert areas elsewhere and the Northern Areas. The most westerly record comes from Duki, Balochistan in Pakistan, while the most easterly record is from the Tangail District in Bangladesh. As this species has been observed in Drosh, in the Chitral Valley, it may also occur in the Kabul River Valley in extreme eastern Afghanistan. There's been at least one report of this species occurring in Bhutan.

Habitat

The Indian cobra inhabits a wide range of habitats throughout its geographical range. It can be found in dense or open forests, plains, agricultural lands ( rice paddy fields, wheat crops), rocky terrain, wetlands, and it can even be found in heavily populated urban areas, such as villages and city outskirts, ranging from sea level to in altitude. This species is absent from true desert regions. The Indian cobra is often found in the vicinity of water. Preferred hiding locations are holes in embankments, tree hollows, termite mounds, rock piles and small mammal dens.

Reproduction

The Indian cobra is oviparous, laying eggs in the months of April through July. The female usually lays between 10 and 30 eggs in rat holes or termite mounds, which hatch 48 to 69 days later. Each hatchling measures in total length (tail included). The hatchlings are independent from birth and have fully functional venom glands.

Venom

The Indian cobra's venom mainly contains a powerful post- synaptic neurotoxin and cardiotoxin. The venom acts on the synaptic gaps of the nerves, thereby paralyzing muscles, and in severe bites leading to respiratory failure or cardiac arrest. The venom components include enzymes such as hyaluronidase that cause lysis and increase the spread of the venom. Envenomation symptoms may manifest between fifteen minutes and two hours following the bite.

In mice, the preferred value is estimated to be 0.56 mg/kg via subcutaneous injection (SC). However, there's a wide range of potency for this species, ranging from 0.22 mg/kg (in Pakistani ''N. naja karachiensis'') to 0.84 mg/kg (Indian specimens). ''Minton (1974)'' reported a value of 0.29 mg/kg SC for specimens from northwest India, along with an average venom yield per bite range between 170 and 250 mg (dry weight). In another study, the average venom yield was 169 mg and a maximum yield of 610 mg (both were dry weights of milked venom). Though it is responsible for many bites, only a small percentage are fatal if proper medical treatment and antivenom are given. Mortality rates for untreated bite victims can vary from case to case, depending upon the quantity of venom delivered by the individual involved. According to one study, it is approximately 20–30%, but in another study involving victims who were given prompt medical treatment, the mortality rate was only 9%. In Bangladesh, it is responsible for most of the snake bite cases.

The Indian cobra is one of the big four snakes of South Asia that are responsible for the majority of human deaths by snakebite in Asia. Polyvalent serum is available for treating snakebites caused by these species.