Egyptian cobra
| Egyptian cobra | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 Egyptian cobra
| ||||||||||||||||||||
| Scientific classification | ||||||||||||||||||||
| ||||||||||||||||||||
| Binomial name | ||||||||||||||||||||
| Naja haje (Linnaeus, 1758)[1][2] | ||||||||||||||||||||
 Distribution of the Egyptian cobra
| ||||||||||||||||||||
| Synonyms | ||||||||||||||||||||
|
The Egyptian cobra (Naja haje) is a species in the genus Naja (cobra) found in Africa. It is one of the largest species of cobra in Africa.
Taxonomy and etymology
The Egyptian cobra was first described by Swedish zoologist Carolus Linnaeus in 1758.[3] The generic name naja is a Latinisation of the Sanskrit word nāgá (नाग) meaning "cobra". The specific epithet haje is derived from the Arabic word hayya (حية) which literally means "snake" or "viper".[4]
The specific name haje is the transliteration of Arabic حية which is the word for snake or viper. The snouted cobra (Naja annulifera) and Anchieta's cobra (Naja anchietae) were formerly regarded as subspecies of Naja haje, but have since been shown to be distinct species.[5][6] The Arabian populations were long recognised as a separate subspecies, Naja haje arabica, and the black populations from Morocco sometimes as Naja haje legionis. A recent study[7] found that the Arabian cobra constitutes a separate species, Naja arabica, whereas the subspecies legionis was synonymised with N. haje. The same study also identified the West African savanna populations as a separate species and described it as Naja senegalensis.
Description
The Egyptian cobra is large in length, slightly depressed to cylindrical, tapered and moderately slender bodied snake with a medium to moderately short length tail. Its body is compressed dorsoventrally and sub-cylindrical posteriorly. The head of this species is broad, flattened and slightly distinct from the neck. The canthus is distinct. The snout is rounded, while the eyes are medium to moderately small in size with round pupils. Dorsal scales are long, smooth and strongly oblique. The Egyptian cobra is one of the largest cobras of the African continent. The average total length of this species is approximately 1.4 m (4.59 ft), but Egyptian cobras may grow up to 2.59 m (8.5 ft) in length.[8] The most recognizable characteristics of this species are its head and hood, which can be spread anywhere from 15 cm (5.91 in) to 18 cm (7.09 in) in width. The colour is highly variable, but most specimens are some shade of brown, often with lighter or darker mottling, and often a "tear-drop" mark below the eye. Some are more copper-red or grey-brown in colour. Specimens from northwestern Africa (Morocco, western Sahara) are almost entirely black. The ventral side is mostly a creamy white, yellow brown, grayish, blue grey, dark brown or black in colouration, often with dark spots.[9]
Scalation
Dorsal scales on the midbody 19-20, ventral scales 191-220, subcaudal scales 53-65 (paired), Anal scale is single, upper labials 6, upper labials to the eye 3+4, preoculars 1, postoculars 3 (but can also be 2), suboculars 2–3, supralabials 7 (rarely 6 or 8), lower labials 8, temporal 1+2/1+3 varying.[9]
Distribution and habitat
Geographical distribution
The geographical range of this species is fragmented, though the species is common where it exists. It can be found across northern Africa in Egypt, Libya, Tunisia, Algeria, Morocco, Western Sahara to Nigeria, Cameroon, in parts of Kenya, Tanzania, Central African Republic, Chad, Ethiopia, Eritrea, Somalia, and much of South Sudan and southeastern Sudan.
Habitat
They occur in a wide variety of habitats like, steppes, dry to moist savannas, arid semi-desert regions with some water and vegetation. This species is frequently found near water. The Egyptian cobra is also found in agricultural fields and scrub vegetation. These cobras do also occur in the presence of humans where they often enter houses. They are attracted to the human villages by chickens and rats that are attracted by garbage. There are also notes of Egyptian cobras swimming in the Mediterranean sea, so they seem to like water where they have been found quite often.[8][9]
Behaviour and ecology
The Egyptian cobra is terrestrial and crepuscular or nocturnal species. It can however, be seen basking in the sun at times in the early morning. This species shows a preference for a permanent home base in abandoned animal burrows, termite mounds or rock outcrops. It is an active forager sometimes entering human habitations, especially when hunting domestic fowl. Like other cobra species, it generally attempts to escape when approached, at least for a few metres but if threatened it assumes the typical upright posture with the hood expanded. This is an especially aggressive species. This species prefers to eat toads, but it will prey on small mammals, birds, eggs, lizards and other snakes.[8]
Venom
The venom of the Egyptian cobra consists mainly of neurotoxins and cytotoxins.[10] The average venom yield is 175 to 300 mg in a single bite, and the murine subcutaneous LD50 value is 1.15 mg/kg.[11]
The venom affects the nervous system, stopping the nerve signals from being transmitted to the muscles and at later stages stopping those transmitted to the heart and lungs as well, causing death due to complete respiratory failure. Envenomation causes local pain, severe swelling, bruising, blistering, necrosis and variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhea, dizziness, collapse or convulsions along with possible moderate to severe flaccid paralysis. Unlike some other African cobras (for example the Red spitting cobra), this species does not spit venom.[12]
Ancient Egyptian culture and history
The Egyptian cobra was represented in Egyptian mythology by the cobra-headed goddess Meretseger. A stylised Egyptian Cobra — in the form of the uraeus representing the goddess Wadjet — was the symbol of sovereignty for the Pharaohs who incorporated it into their diadem. This iconography was continued through the period of Ptolemaic Egypt (305 BC-30 BC).
Most ancient sources say that Cleopatra and her two attendants committed suicide by being bitten by an aspis, which translates into English as "asp". The snake was reportedly smuggled into her room in a basket of figs. Plutarch wrote that she performed experiments on condemned prisoners and found aspis venom to be the most painless of all fatal poisons.[13] This "aspis" was probably Naja haje (the Egyptian cobra). However, the accounts of her apparent suicide have been questioned, since death from this snake's venom is relatively slow, and the snake is large, so it would be hard to conceal.[14]
Cited references
- ↑ Naja haje (TSN 700627) at Integrated Taxonomic Information System. Accessed 23 June 2012.
- ↑ Naja haje (LINNAEUS, 1758) at The Reptile Database. Accessed 23 June 2012.
- ↑ Linnaeus, C. 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Laurentii Salvii, Holmiæ. 10th Edition: 824 pp.
- ↑ Wuster, Wolfgang; Wallach, Van; Broadley, Donald G. (2009). "In praise of subgenera: taxonomic status of cobras of the genus Naja Laurenti (Serpentes: Elapidae)". Zootaxa 2236 (1): 26–36. Retrieved on 23 June 2012.
- ↑ Broadley, D.G. (1995). The snouted cobra, Naja annulifera, a valid species in southern Africa. Journal of the Herpetological Association of Africa, 44, 26–32.
- ↑ Broadley, D.G. & Wüster, W. (2004) A review of the southern African ‘non-spitting’ cobras (Serpentes: Elapidae: Naja). African Journal of Herpetology, 53, 101–122.
- ↑ Trape, J.-F., L. Chirio, D.G. Broadley & W. Wüster (2009) Phylogeography and systematic revision of the Egyptian cobra (Serpentes: Elapidae: Naja haje) species complex, with the description of a new species from West Africa. Zootaxa 2236: 1-25.
- ↑ 8.0 8.1 8.2 Egyptian cobra (General Details) at Clinical Toxinology. Accessed 23 June 2012.
- ↑ 9.0 9.1 9.2 Mastenbroek, Richard. Captive Care of the Egyptian Cobra (Naja haje). Devenomized. www.devenomized.com. Retrieved on 23 June 2012.
- ↑ Joubert, FJ; Taljaard N (October 1978). "Naja haje haje (Egyptian cobra) venom. Some properties and the complete primary structure of three toxins (CM-2, CM-11 and CM-12).". European Journal of Biochemistry 90 (2): 359–367. PMID 710433. Retrieved on 23 June 2012.
- ↑ Fry, Dr. Bryan Grieg. Sub-cutaneous LD-50s. Australian Venom Research Unit. University of Queensland. Retrieved on 23 June 2012.
- ↑ Bogert, C.M. (1943) Dentitional phenomena in cobras and other elapids with notes on adaptive modifications of fangs. Bulletin of the American Museum of Natural History, 81, 285–360.
- ↑ Plutarch Parallel Lives, "Life of Antony"
- ↑ Richard Girling Cleopatra and the asp The Times November 28, 2004