The generic name and the specific epithet naja is a Latinisation of the Sanskrit word nāga (नाग) meaning "cobra".[8]
The Indian cobra is classified under the genus Naja of the family Elapidae. The genus was first described by Josephus Nicolaus Laurenti in 1768.[9] The species Naja naja was first described by the Swedish physician, zoologist, and botanist Carl Linnaeus in 1758.[4][10] 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.[11] The Indian cobra is a moderately sized, heavy-bodied species. This cobra species can easily be identified by its relatively large and quite impressive 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.[14]
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.[15] The majority of adult specimens range from 1 to 1.5 metres (3.3 to 4.9 ft) in length. Some specimens, particularly those from Sri Lanka, may grow to lengths of 2.1 to 2.2 metres (6.9 to 7.2 ft), but this is relatively uncommon.[14] The Indian cobra's venom mainly contains a powerful post-synaptic neurotoxin[15] and cardiotoxin.[15][19] 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.[20][21]
In mice, the preferred LD50 value is estimated to be 0.56 mg/kg via subcutaneous injection (SC).[15][22] However, there's a wide range of potency for this species, ranging from 0.22 mg/kg (in Pakistani N. naja karachiensis)[23] to 0.84 mg/kg (Indian specimens).[24] 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).[15] In another study, the average venom yield was 169 mg and a maximum yield of 610 mg (both were dry weights of milked venom).[22] Though it is responsible for many bites, only a small percentage are fatal if proper medical treatment and antivenom are given.[18] 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%,[25] 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.[26]