The Andaman cobra (''Naja sagittifera'') is a species of cobra

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

Andaman Islands The Andaman Islands () are an archipelago in the northeastern Indian Ocean about southwest off the coasts of Myanmar's Ayeyarwady Region. Together with the Nicobar Islands to their south, the Andamans serve as a maritime boundary between th ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. The name of this cobra comes from the Islands itself. The species has a very potent venom, and is capable of “spitting”, although this defensive behavior is very rare and the aim is poor and not as efficient as “true spitting cobras”.

Taxonomy

''Naja sagittifera'' is classified under the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Naja ''Naja'' is a genus of venomous elapid snakes commonly known as cobras (or "true cobras"). Members of the genus ''Naja'' are the most widespread and the most widely recognized as "true" cobras. Various species occur in regions throughout Afric ...

'' of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Elapidae Elapidae (, commonly known as elapids ; grc, ἔλλοψ ''éllops'' "sea-fish") is a family of snakes characterized by their permanently erect fangs at the front of the mouth. Most elapids are venomous, with the exception of the genus Emydoceph ...

. It was first described by Frank Wall, a

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...

physician A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...

and

herpetologist Herpetology (from Greek ἑρπετόν ''herpetón'', meaning "reptile" or "creeping animal") is the branch of zoology concerned with the study of amphibians (including frogs, toads, salamanders, newts, and caecilians (gymnophiona)) and rept ...

in 1913. The

generic Generic or generics may refer to: In business * Generic term, a common name used for a range or class of similar things not protected by trademark * Generic brand, a brand for a product that does not have an associated brand or trademark, other ...

name ''Naja'' is a Latinization of the

Sanskrit Sanskrit (; attributively , ; nominally , , ) is a classical language belonging to the Indo-Aryan branch of the Indo-European languages. It arose in South Asia after its predecessor languages had diffused there from the northwest in the late ...

word ' (), meaning "cobra”. The

specific Specific may refer to: * Specificity (disambiguation) * Specific, a cure or therapy for a specific illness Law * Specific deterrence, focussed on an individual * Specific finding, intermediate verdict used by a jury in determining the fina ...

epithet ''sagittifera'' is Latin and means “arrow-bearing” or “carrying arrows”. The Caspian cobra (''Naja oxiana'') and

Monocled cobra The monocled cobra (''Naja kaouthia''), also called monocellate cobra and Indian spitting cobra, is a venomous cobra species widespread across South and Southeast Asia and listed as Least Concern on the IUCN Red List. Taxonomy The scientific n ...

(''Naja kaouthia'') have been demonstrated to be sister clades to ''Naja sagittifera''. Noticeably, despite population separation caused by the

Hindu Kush The Hindu Kush is an mountain range in Central and South Asia to the west of the Himalayas. It stretches from central and western Afghanistan, Quote: "The Hindu Kush mountains run along the Afghan border with the North-West Frontier Provinc ...

mountains, ''N. oxiana'' demonstrates a single evolutionary lineage, suggesting historic rapid range expansion. ''N. oxiana'' is a non-spitter unlike ''N. kaouthia'' and ''N. sagittifera''.

Description

The Andaman cobra is medium to large sized snake in length, is a heavy bodied snake with long cervical ribs capable of expansion to form a hood when threatened, it may also spit its venom into the eyes, although not as accurately as the true spitting cobras. Body is compressed dorsoventrally and sub-cylindrical posteriorly. The average length of these snakes is about , but they can grow to about regularly, although the longest specimen found measured . Adults come in three color patterns: a) Uniform glossy black above, with indistinct black monocle hood mark. Glossy dark-gray below. Head black, with pale white patches on shields. b) Light brown or creamish above, with indistinct black lines round the body and tail and indistinct black monocle hood mark, with brown centre. Pale brown below. Head light brown, spotted with black. c) Uniform grayish above, with distinct black narrow, irregular cross-bars on the body and tail and distinct black monocle hood mark, with gray centre. Grayish below. Head black, with pale white patches on shields. Juveniles have broad black cross-band on throat or underside of neck. Juveniles are glossy black above with a series of narrow, white, irregular cross-bars on body and tail, which show 'A' shape marks when seen from the side. There is a distinct white monocle mark, with black centre. Monocle mark becomes black with the age, also a broad white band below monocle mark disappears with age. Black below. Head black, with some shields blueish-white.

Scalation

Head broad, slightly distinct from neck. Eye medium, with round pupil; nostrils large; frontal small; no loreal; 1 preocular in contact with posterior nasal; 3 postoculars; temporals 2+1 or 2+2. Scales smooth, in 27-29 : 21-23 : 15-17 rows; supralabials 7 ( 3rd and 4th in contact with the eye ), 7th longest, elongated; cuneates 1 on each side; infralabials 8, first 4 touching the first pair of genials; ventrals 172–184; subcaudals 60–64, paired; anal entire.

Distribution

This species is endemic to Andaman and Little

Venom

Using WHO-recommended protocols, venom potencies of this species and its congener from mainland India (''Naja naja'') were evaluated in a murine model of envenoming. The results indicated that the of ''N. sagittifera'' venom was 0.475 mg/kg via

intravenous injection Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutri ...

. Like ''N. kaouthia'' and ''N. atra'', this isn't a “true spitting cobra”. It may, in rare instances, eject venom. If venom gets into the eye, it can cause intense pain and blindness if left untreated. Cobras that cause both extensive & local effects, with or without flaccid paralysis, such as

Naja kaouthia The monocled cobra (''Naja kaouthia''), also called monocellate cobra and Indian spitting cobra, is a venomous cobra species widespread across South and Southeast Asia and listed as Least Concern on the IUCN Red List. Taxonomy The scientific n ...

, generally cause a painful bite, with progressive swelling and, if

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

develops, there is often discolouration of the skin and/or blistering first. This may progress to full thickness skin

over 3-7 days. Such wounds may be extensive, can sometimes involve underlying tissues, and may be difficult to heal. There is a potential for both secondary infection and long term morbidity. Squamous cell carcinoma can develop in such long-term sores. In addition to these local effects, there may be systemic symptoms, such as headache, nausea, vomiting, abdominal pain and less commonly, evidence of mild, sometimes moderate to severe flaccid paralysis. This may develop within a few hours or be delayed (greater than 12 hrs before onset). Ptosis is usually the first sign, followed by

ophthalmoplegia Ophthalmoparesis refers to weakness (-paresis) or paralysis (-plegia) of one or more extraocular muscles which are responsible for eye movements. It is a physical finding in certain neurologic, ophthalmologic, and endocrine disease. Internal o ...

, then if it progresses, dysarthria, dysphagia, poor tongue extrusion, drooling, limb weakness, lastly respiratory paralysis. Relative rates of necrosis versus paralysis for ''Naja kaouthia'' vary between studies, but it appears necrosis will develop in about 10-40% of cases, while paralysis occurs in >50% of cases. Infection of the bite area is also common, as high as 58% of cases. Dry bites constitute roughly 20-40% of all bites.

References

Naja Reptiles of India Endemic fauna of the Andaman Islands Reptiles described in 1913 Taxa named by Frank Wall {{Snake-stub