Indian cobra

Source: Wikipedia, the free encyclopedia.
Not to be confused with King cobra or monocled cobra.

Indian cobra

Least Concern  (IUCN 3.1)[1]
CITES Appendix II (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Genus: Naja
Species:
N. naja
Binomial name
Naja naja
Map of South Asia showing highlighted range covering almost all of India and portions of adjoining countries
Indian cobra distribution
Synonyms[3][5]
  • Coluber naja Linnaeus, 1758
  • Naja brasiliensis Laurenti, 1768
  • Naja fasciata Laurenti, 1768
  • Naja lutescens Laurenti, 1768
  • Naja maculata Laurenti, 1768
  • Naja non-naja Laurenti, 1768
  • Coluber caecus Gmelin, 1788
  • Coluber rufus Gmelin, 1788
  • Coluber Naja Shaw & Nodder, 1791
  • Coluber Naja Shaw & Nodder, 1794
  • Naja tripudians Merrem, 1820
  • Naja nigra Gray, 1830
  • Naja tripudians forma typica Boulenger, 1896
  • Naja tripudians var. caeca Boulenger, 1896
  • Naja naja naja Smith, 1943
  • Naja naja gangetica
    Deraniyagala
    , 1945
  • Naja naja lutescens
    Deraniyagala
    , 1945
  • Naja naja madrasiensis
    Deraniyagala
    , 1945
  • Naja naja indusi
    Deraniyagala
    , 1960
  • Naja naja bombaya
    Deraniyagala
    , 1961
  • Naja naja karachiensis
    Deraniyagala
    , 1961
  • Naja naja ceylonicus Chatman & Di Mari, 1974
  • Naja naja polyocellata Mehrtens, 1987
  • Naja ceylonicus Osorio E Castro & Vernon, 1989
  • Naja (Naja) naja — Wallach, 2009

The Indian cobra (Naja naja), 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.[6][7]

It is distinct from the

snake charmers. It is a protected species under the Indian Wildlife Protection Act
(1972).

Taxonomy

The

Sanskrit word nāga (नाग) meaning "cobra".[8]

The Indian cobra is classified under the genus

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]

Naja
(Naja)

Naja (Naja) naja

Naja (Naja) kaouthia

Naja (Naja) atra

Naja (Naja) sagittifera

Naja (Naja) oxiana

Naja (Naja) sputatrix

Naja (Naja) samarensis

Naja (Naja) philippinensis

Naja (Naja) mandalayensis

Naja (Naja) sumatrana

Naja (Naja) siamensis

(
Afronaja
)

Naja (Afronaja) pallida

Naja (Afronaja) nubiae

Naja (Afronaja) katiensis

Naja (Afronaja) nigricollis

(Boulengerina)

Naja (Boulengerina) multifasciata

Naja (Boulengerina) savannula

Naja (Boulengerina) subfulva

Naja (Boulengerina) guineensis

Naja (Boulengerina) peroescobari

Naja (Boulengerina) melanoleuca

(Uraeus)

Naja (Uraeus) nivea

Naja (Uraeus) senegalensis

Naja (Uraeus) haje

Naja (Uraeus) arabica

Naja (Uraeus) annulifera

Naja (Uraeus) anchietae

Local names

The Indian cobra[12][13] or spectacled cobra,[6] being common in South Asia, is referred to by a number of local names deriving from the root of Naga.

For Indo-Aryan and Dravidian languages:

  • Phetigom (ফেতিগোম) in Assamese
  • Gokhra (গোখরো) in Bengali
  • Naag (नाग) in Hindi,
  • Fetaar (फेटार) in
    Awadhi
  • Gehuan (गेहुंअन)in Magahi and Bhojpuri
  • Domi (डोमी) in
    Chhattisgarhi
  • Naag (નાગ) in Gujarati
  • Nagara Haavu (ನಾಗರ ಹಾವು) in Kannada
  • Moorkkan (മൂര്‍ഖന്‍) in Malayalam
  • Naag (नाग) in Marathi
  • Gokhara Saapa (ଗୋଖର ସାପ) or Naaga Saapa (ନାଗ ସାପ) in Odia
  • Naya (නයා) or Nagaya (නාගයා) in
    Sinhalese
  • Nalla pambu (நல்ல பாம்பு) or Nagapambu (நாகப்பாம்பு) in Tamil
  • Nagu Paamu(నాగు పాము) in Telugu
  • Saanp ( سانپ/sɑ̃ːp/) in Urdu
  • "Uchchu" (Tulu Language)

Description

Spectacle pattern

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 (

spectacles.[14]

This species has a head which 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]

A 6.5 ft cobra captured in a village in Odisha

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.

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.

A large Indian cobra

Scalation

Dorsal scales are smooth and strongly oblique. Midbody scales are in 23 rows (21–25), with 171–197

postoculars. Temporals are 2 + 3.[15]

Similar species

Typical patterning on the body of a rat snake (pictured above). Indian cobras do not have this type of patterning

The Oriental rat snake

Wallophis brachyura.[6] 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.[16]

Distribution and habitat

Silent film showing an African chameleon and an Indian cobra by Raymond L. Ditmars (?) Collection EYE Film Institute Netherlands.

The Indian cobra is native to 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.[14] There's been at least one report of this species occurring in Bhutan.[17]

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 2,000 metres (6,600 ft) 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.[15][18]

Reproduction

Indian cobras are

eggs
between the months of April and July. The female snake usually lays between 10 and 30 eggs in rat holes or termite mounds and the eggs hatch 48 to 69 days later. The hatchlings measure between 20 and 30 centimetres (8 and 12 in) in length. The hatchlings are independent from birth and have fully functional venom glands.

Venom

The Indian cobra's venom mainly contains a powerful post-

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

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]

Spectacled cobra with hood lowered in a bamboo shrub

The Indian cobra is one of the

Zedoary, a local spice with a reputation for being effective against snakebite,[28] has shown promise in experiments testing its activity against cobra venom.[29]

The venom of young cobras has been used as a substance of abuse in India, with cases of snake charmers being paid for providing bites from their snakes. Though this practice is now seen as outdated, symptoms of such abuse include loss of consciousness, euphoria, and sedation.[30]

As of November 2016, an antivenom is currently being developed by the Costa Rican Clodomiro Picado Institute, and the clinical trial phase is in Sri Lanka.[31]

Envenomation and clinical manifestation

Indian cobras (N. naja) earliest clinical manifestation of systemic envenoming was drowsiness, which occurred in 60% of cases starting at 30 minutes (severe bites) post-envenomation to 3 hours post bite. Difficulty in opening the eyes, speaking, opening the mouth, moving the lips and swallowing followed 1 – 4 hours later. Ptosis developed 1.6 – 6 hours post bite in all cases of systemic envenoming. General weakness was usually the last symptom to develop, followed by paralysis of the muscles in severe cases. Three patients developed respiratory paralysis and were given artificial respiration; 2 recovered and 1 died. The fatal case developed respiratory paralysis about 10 minutes before reaching hospital and patient became comatose; tracheostomy and artificial respiration were performed immediately and antivenom was administered intravenously. Patient survived for 8 days but finally died. The outstanding feature of systemic envenoming is paralysis of the muscles due to rapid action of neurotoxin at the myoneural junction. Respiratory paralysis may occur within 3 – 4 hours in severe cases.

Indian cobra bites are very common in many parts of India, Pakistan, Sri Lanka, and throughout their range in South Asia. Hundreds of individual case reports have been published in books and journals over the past century. It is astonishing, however, that no large prospective study of patients with proven bites by N. naja has been undertaken and reported. In a survey of snakebites in India, 91.4% of cases were bitten by an unidentified snake. Of the 6.1% of identified venomous snakes responsible for bites, 40% were N. naja. As with bites by N. kaouthia and N. oxiana, patients may show manifestations of systemic neurotoxic envenoming or local envenoming or both, although N. oxiana bites produce noticeable symptoms of envenomation more rapidly and prominent neurotoxicity (severe flaccid paralysis) is more common amongst patients bitten by N. oxiana. A woman bitten by N. oxiana in northwestern Pakistan suffered prominent neurotoxicity and died while en route to the closest hospital nearly 50 minutes after envenomation (death occurred 45–50 minutes post envenomation).[32]

Local necrosis was described after cobra bites in India in the 1860s and up to the 1920s but this was apparently forgotten until Reid's work in Malaysia. Severe local pain and swelling may begin almost immediately after the bite. The pain persists while swelling and tenderness extend up the bitten limb, sometimes spreading to the adjacent trunk. Darkening of the necrotic area of skin and blistering are apparent by about the third day with a characteristic putrid smell typical of necrotic cobra bites in Africa and Asia. Early systemic symptoms include headache, nausea, vomiting, dizziness and a feeling of lassitude, drowsiness and intoxication. "Many subjects describe their drowsiness as if they had imbibed large quantities of some potent intoxicant." Neurotoxic symptoms begin with ptosis (the patient puckers their brow, contracting the frontalis muscle, attempting to raise the eyelids or tilts the head back so as to see beneath the drooping upper lids), profuse viscid saliva, inability to clear secretions, sagging of the jaw or inability to open the mouth and progression to respiratory paralysis. It is not clear from the available literature whether the proportion of patients developing neurotoxicity and necrosis is different from that in patients bitten by N. kaouthia.[33]

Between 1968 - 1974, clinical observations were made on 20 cases of cobra bites in Thailand. Most of the patients came from the rural health centres and the cobra responsible for the bite was identified as Naja naja (Indian cobra). All 20 patients developed systemic envenoming. Antivenom for cobra bite was administered intravenously together with symptomatic and supportive treatment; 19 patients survived and 1 died from cerebral anoxia.[34]

The outstanding feature of systemic envenoming is paralysis of the muscles due to rapid action of neurotoxin at the myoneural junction.

Tracheostomy and artificial respiration are essential in cases of respiratory failure. Necrosis is the outstanding feature of local envenoming. Most patients were bitten on foot while working in rice fields. Authors recommended the wearing of shoes or boots while working, and that persons bitten by a snake apply a firm ligature above the bite and go to the nearest health centre or hospital.[15][33]

Genome

Previous cytogenetic analysis revealed the Indian cobra has a diploid

next-generation sequencing and emerging genomic technologies, a de novo high-quality N. naja reference genome was published in 2020.[36] The estimated size of this haploid genome is of 1.79 Gb, which has 43.22% of repetitive content and 40.46% of GC content. Specifically, macro-chromosomes, which represent 88% of the genome, have 39.8% of GC content, while micro-chromosomes, that represent only 12% of the genome, contain 43.5% of GC content.[36]

Synteny analysis

Synteny analysis between the Indian cobra and the prairie rattlesnake genome revealed large syntenic blocks within macro, micro, and sexual chromosomes. This study allowed the observation of chromosomic fusion and fission events that are consistent with the difference in chromosome number between these species. For example, chromosome 4 of the Indian cobra shares syntenic regions with chromosomes 3 and 5 of the rattlesnake genome, indicating a possible fusion event. Besides, chromosomes 5 and 6 of the Indian cobra are syntenic to rattlesnake chromosome 4, indicating a possible fusion event between these chromosomes.[36]

On the other hand, by performing whole-genome synteny comparison between the Indian cobra and other reptilian and avian genomes, it was revealed the presence of large syntenic regions between macro, micro, and sexual chromosomes across species from these classes, which indicates changes in chromosome organization between reptile and avian genomes and is consistent with their evolutionary trajectories.[36]

Gene organization

Using protein homology information and expression data from different tissues of the cobra, 23,248 protein-coding genes, 31,447 transcripts, and 31,036 proteins, which included alternatively spliced products, where predicted from this genome. 85% of these predicted proteins contained start and stop codon, and 12% contained an N-terminal secretion signal sequence, which is an important feature in terms of toxins secretion from venom glands.[36]

Venom gland genes

Further studies on gene prediction and annotation of the Indian cobra genome identified 139 toxin genes from 33 protein families. These included families like

cathelicidins and phospholipase B-like toxins.[36]

Venom gland transcriptome and toxin gene identification

Indian cobra venom composition classified in venom specific or accessory proteins based on genomic annotation and transcriptomic data by Suryamohan et al., 2020.

Analysis of transcriptomic data from 14 different tissues of the Indian cobra identified 19,426 expressed genes. Out of these genes, 12,346 belonged to the venom gland transcriptome, which included 139 genes from 33 toxin gene families. Additionally, differential expression analysis revealed that 109 genes from 15 different toxin gene families were significantly up-regulated (fold change > 2) in the venom gland and this included 19 genes that were exclusively expressed in this gland.[36]

These 19 venom specific toxins (VSTs) encode the core effector toxin proteins and include 9 three-finger toxins (out of which six are

coagulation factors, protein disulfide isomerases, natriuretic peptides, hyaluronidases, phospholipases, L-amino acid oxidase (LAAO), vascular endothelial growth factor (VEGF) and 5' nucleotidases.[36]

This transcriptomic data together with the information provided by the high quality Indian cobra genome generated by Susyamohan et al., 2020 suggest that these VSTs together with AVPs form the core toxic effector components of this venomous snake, which induce muscular paralysis, cardiovascular dysfunction, nausea, blurred vision and hemorrhage after snake bite.[36][37]

The identification of these genes coding for core toxic effector components from the Indian cobra venom may allow the development of recombinant antivenoms based in neutralizing antibodies for VST proteins.[36]

Popular culture

Cobra in a basket, raising its head and spreading its hood
Indian cobras as part of the heraldry of a princely state of India; the Kalahandi State coat of arms.

There are numerous myths about cobras in India, including the idea that they mate with rat snakes.[38]

Rudyard Kipling's short story "Rikki-Tikki-Tavi" features a pair of Indian cobras named Nag and Nagaina, the Hindi words for male and female snake, respectively.

Hinduism

The Indian cobra is often featured in

Naga Panchami and Nagula Chavithi
. When killed by humans, it is usually cremated with milk and ghee along with a cloth by Hindus.

Snake charming

The Indian cobra's celebrity comes from its popularity with

snake charmers. The cobra's dramatic threat posture makes for a unique spectacle, as it appears to sway to the tune of a snake charmer's flute. Snake charmers with their cobras in a wicker basket are a common sight in many parts of India only during the Nag Panchami or Naagula Chavithi festival. The cobra is deaf to the snake charmer's pipe, but follows the visual cue of the moving pipe and it can sense the ground vibrations from the snake charmer's tapping. Sometimes, for the sake of safety, the cobra will either be venomoid or the venom will have been milked prior to the snake charmer's act. The snake charmer may then sell this venom at a very high price. In the past Indian snake charmers also conducted cobra and mongoose fights. These gory fight shows, in which the snake was usually killed, are now illegal.[39]

Heraldry

Indian cobras were often a heraldic element in the official symbols of certain ancient princely states of India such as Gwalior, Kolhapur, Pal Lahara, Gondal, Khairagarh and Kalahandi, among others.[40]

Gallery

  • Indian cobra displaying an impressive hood
    Indian cobra displaying an impressive hood
  • Albino spectacled cobra
    Albino spectacled cobra
  • Binocellate cobra
    Binocellate cobra
  • Indian cobra outside a home in Yelandur, Karnataka, South India
    Indian cobra outside a home in Yelandur, Karnataka, South India
  • Cobra regurgitating
    Cobra regurgitating

References

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  15. ^ a b c d e f g h "Naja naja". University of Adelaide. Archived from the original on 2014-12-08. Retrieved 2011-11-10.
  16. ^ "Naja oxiana". Venom Street. Collector and Breeder of Asian Cobras. Venom Street. Archived from the original on 21 October 2014. Retrieved 3 February 2012.
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  40. ^ Heraldry of Madhya Pradesh Archived 2015-12-22 at the Wayback Machine. hubert-herald.nl

External links

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