Cobra
From Wikipedia, the free encyclopedia
A cobra (pronunciation ) is a venomous snake of family Elapidae, of several genera, but particularly Naja. (Non-cobra elapidae include the taipans, brown snakes, tiger snakes, fierce snakes, coral snakes, mambas and sea snakes.) Cobras generally inhabit tropical and desert regions of Asia and Africa.
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[edit] Appearance and description
The cobra's most recognizable feature is its hood, a section of its neck which it can flatten outwards in a threat display to appear larger. Since snakes do not have a sternum they can stretch their ribs outwards which expands the hood. The hood can also carry distinctive markings. The hood of the Asian cobra is proportionately much larger than that of the king cobra and is usually yellow to brown, with a black-and-white spectacle pattern on top and two black and white spots on the lower surface. Most snakes can flatten their necks to some degree; cobras are only more adept. Cobras come in varying colors from black or dark brown to yellowish white. Elapidae cannot fold their fangs down, as Viperidae can, so their fangs are generally shorter. Most cobras are quite large, reaching on average 1.2–2.5m (3.9-8.2 ft) long.
Cobra is the Portuguese (and old Galician) common name for a snake; it came from late Latin colobra (from the classical Latin coluber, colubra). When Portuguese navigators arrived on the coasts of Africa and South Asia in the 16th century, they named the cobra "cobra-capelo", or "hood-snake"; from this compound, the name entered Spanish, French, English, and other European languages. Today, mainly in Brazil, cobras are known basically as najas.
Among the most notable attributes of the Cobra is their powerful venom.
[edit] Types of cobra
The most common cobra is the Adrian Spectacled cobra Naga, native to the Indian subcontinent and associated with snake charming there. The Black cobra, found in Pakistan and North India, is generally considered to be a sub-species.[citation needed]
The second most common cobra species is the Monocled cobra, Naga kaouthia, widespread in Asia.
In addition to a deadly bite, the Spitting cobra can incapacitate larger would-be predators by spraying venom into their eyes. This is extremely painful and can cause permanent blindness, but if washed out promptly rarely causes permanent damage.
The King cobra is ophiophagous; it feeds almost entirely on other snakes, even venomous ones, although it sometimes preys on small rodents and birds. It will only attack humans if provoked or in other extreme circumstances that threaten its survival. If not treated, a king cobra's bite can kill a person in just half an hour. King Cobras may reach up to 5.2m (17.1ft) in length, making them the largest venomous snakes in the world.
In 2003, a new species of cobra was discovered at London Zoo in a shipment of illegal exotic pets. When zoo scientists thought they had a new species they brought in Dr. Wuster who confirmed their belief. Although bearing a resemblance to the Red Spitting Cobra DNA tests confirmed that it is in fact a new species altogether. Studies indicated that it originated from an area of Egypt and Sudan formerly known as Nubia. The new species, Naja nubiae or Nubian Spitting Cobra, has since bred at London Zoo.
[edit] Cobra venom
The snake will only attack a human if provoked or in other extreme circumstances which threaten its survival. Furthermore, for a dangerously venomous snake, the cobra's strikes are quite slow when compared to the extremely rapid strikes of such species as rattlesnakes. Additionally, not all bites result in envenomation and in the case of the Cobra the amount of "blank" strikes may be quite high: in one series of recorded bites in Malaysia only 55% of strikes have included envenomation. Cobra bites are fatal in about 10% of human cases. However, as with any venomous snake, any bite from a cobra should be treated as a potentially fatal injury and medical attention should be sought immediately after the bite occurs. As with all elapids, the venom of cobras is highly neurotoxic and dangerous. Therefore, any cobra bite must be regarded as life-threatening and professional medical assistance should be immediately sought. Early symptoms of a bite include ptosis, diplopia , dysphagia, and dizziness, followed by progressive respiratory muscle weakness, ultimately requiring endotracheal intubation. Cobra venom is a postsynaptic neurotoxin. It works by stopping the acetylcholine molecules in the diaphragm muscle from interacting. Without treatment death from respiratory failure may occur as early as 30 minutes after being bitten.
Standard treatment involves the use of antivenin. Additionally, it is possible to support bite victims via mechanical ventilation, using equipment of the type generally available at hospitals. If too far away from a hospital, doctors prefer the "suck and spit" formation. Such support should be provided until the venom is metabolised and the victim can breathe unaided. If death occurs it takes place approximately 6 to 12 hours after the cobra bite. Cause of death is respiratory failure or suffocation caused by complete paralysis of the diaphragm.
[edit] Rhythm
Indian "saperas" claim to spectators that they can charm a cobra by playing music. The sapera plays a flute, swaying it from side to side and the cobra sways in time with the music, apparently hypnotized. In fact, the cobra is not reacting to the music as snakes do not have hearing. What prompts it to perform is the snake charmer's clever manipulation of the cobra's natural tendencies. When suddenly thrust into the open air from the darkness of the basket, the snake rises up and spreads its hood, its normal reaction to a threat. It sees the swaying pipe and mistakes it for another snake. That error, together with the charmer's movements in time with the music, holds the snake's attention and follows the movement of the instrument. As the charmer moves the pipe, so the cobra bobs its head.
However, the following must be taken into consideration: The New Encyclopaedia Britannica (1987, Vol. 27, p. 159) states: “This supposition is incorrect; snakes are sensitive to some airborne sound waves and are able to receive them through a mechanism that serves as a substitute for the tympanic membrane. . . . Moreover, while the sensitivity of most snakes to the middle of the low-tone range is below that of most other types of ears, it is not seriously so. In a few snakes, however, the sensitivity is about as keen as in the majority of lizards with conventional types of ear openings and middle-ear mechanisms.”
[edit] References
[edit] External links
- The Asiatic Cobra Systematics Page
- Richard Mastenbroek's Elapid Pages, captive care information
