Definitions

cobra

cobra

[koh-bruh]
cobra, name for African and Asian snakes of the family Elapidae that are equipped with inflatable neck hoods. The family also includes the African mambas, the Asian kraits, the New World coral snakes and a large number of Australian snakes. All members of the family are poisonous and have short, rigid fangs attached at the front of the mouth. Cobras are found in most of Africa and in S Asia. They are nocturnal hunters, and most feed on small mammals, birds, and frogs. Females of all but one species lay eggs. The hood, which serves as a warning device, consists of loose skin around the neck; when the snake is excited it spreads the hood by extending the underlying long, movable ribs, and inflating it with air from the lungs. The king cobra (Ophiophagus hannah), or hamadryad, largest of all venomous snakes, is found in S Asia; it may reach a length of 18 ft (5.5 m) and feeds chiefly on other snakes. The Indian cobra (Naja naja), a common snake of the same region, is usually 4 to 5 ft (1.2-1.6 m) long; its large hood is marked on the back by a pattern of figures resembling eyes. It preys on rats and is therefore often found in houses. The Indian cobra and the Egyptian cobra (Naja haja) are often displayed by snake charmers. The cobras appear to respond to the music played by the charmer, but, like all snakes, they are deaf and only follow the movements of the charmer. As cobras do not strike accurately during the day, charmers are seldom bitten. Most cases of snakebite from cobras occur when humans walking barefoot at night disturb the animal. Cobra venom is not as toxic as that of some other members of the family; the fatality rate among human victims is thought to be about 10%. Some African cobras can eject a spray of venom through the openings of the fangs, aiming accurately to a distance of at least 6 ft (1.8 m). Among these is the ringhals (Hemachatus hemachatus) of S Africa, which aims the spray at the eyes of the victim, causing great pain and sometimes blindness. The ringhals is the only cobra that bears live young. Cobras are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Squamata, family Elapidae.

Black-necked cobra (Naja nigricollis)

Any of several highly venomous elapid snakes that expand their neck ribs to form a hood. They are found in warm regions of Africa, Australia, and Asia. Cobra bites are fatal in about 10percnt of human cases. Cobras feed primarily on small vertebrates. The Indian cobra (Naja naja) kills several thousand people annually, mostly because it enters houses to catch rats. The king cobra (Ophiophagus hannah) is the world's largest venomous snake, often more than 12 ft (3.5 m) long. Some African cobras can spit their venom more than 6 ft (1.8 m). Cobras are favourites of snake charmers, who, by their movements rather than their music, tease the deaf snakes into assuming the upreared defense posture.

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Cobras are venomous snakes of the 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. When feeling threatened, cobras can rear up and flatten their heads into an instantly recognisable warning posture. The rest of the time their heads are symmetrical and they look much like any other snake.

Types of cobra

The most common cobra is the Spectacled cobra Naja naja, 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.

The second most common cobra species is the Monocled cobra, Naja 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 i.e. 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.

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. 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.

Rhythm and Rituals

Pakistani and 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, the cobra bobs its head several times.

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.”

References

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