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Friday, January 14, 2011

Venomous Snakes _ Toxic members of Animal Planet

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Most Venomous Snakes of the world _ Part-1
Cobras, vipers, and closely related species use venom to immobilize or kill their prey. The venom is modified saliva, delivered through fangs. The fangs of 'advanced' venomous snakes like viperids and elapids are hollow to inject venom more effectively, while the fangs of rear-fanged snakes such as the boomslang merely have a groove on the posterior edge to channel venom into the wound. Snake venoms are often prey specific, their role in self-defense is secondary.




1.  Boomslang
A boomslang, Dispholidus typus is a large, venomous colubrid snake native to sub-Saharan Africa. It is the only species in its genus. Its name means “tree snake” in Afrikaans and Dutch. Boomslangs are largely arboreal, are very fast moving, and are oviparous. Their diet includes chameleons and other arboreal lizards, frogs, and occasionally small mammals, birds and eggs from nesting birds, which they swallow whole.
Most members of the colubrid family are harmless, or have relatively weak venom, but the boomslang is an exception. It has a highly potent venom which it delivers through large, deeply grooved fangs that are (like in most other venomous colubrids) located in the rear of the jaw. 

This type of venomous apparatus is called opisthoglypha. The boomslang is the most dangerous of the snakes with this method of venom delivery, due to its relatively large fangs and its relatively anterior position of the fangs compared to other opisthoglyphic taxa. The bite of the boomslang can be fatal, and has been reported to be not unlike bites from vipers. The venom of a boomslang disables blood clotting process and the victim often dies out of numerous internal and external bleedings.  

Other symptoms include: headache, nausea, sleepiness and mental disorders. Being relatively slow-acting venom, the symptoms may occur many hours after the bite. On one hand, this provides time for arranging the serum, while on the other hand it may lead victims to underestimate the bite (especially when, as with other snakes, not every bite injects venom).
An adult snake has 4-8 mg of venom. 5 mg is said to be enough to kill a man. The boomslang is a timid snake, and bites generally occur only while attempting to handle, catch or kill the snake.



2. Black Mamba 
The Black Mamba is found throughout most countries in Sub-Saharan Africa and is incredibly fast, traveling at speeds of up to 12 miles per hour. It's also large; the second largest snake in Africa, averaging 8.2' (2.5m) and getting as long as 14' (4.5m). The Black Mamba is aggressive and territorial, characteristics not usually attributed to snakes. This snake is usually found in an olive green color - it's the inside of its mouth that is black!
African villagers and experts alike fear the intense pain and suffering the mamba inflicts on its victims. Its poison is neuro-toxic. Unlike most poisonous snakes where the venom travels slowly through the blood stream, allowing a victim time to get treatment and to isolate the poison using a tourniquet, the black mamba's poison goes straight for the nerves, attacking the central nervous system and shutting down major organs. Twenty minutes after being bitten you may lose the ability to talk. After one hour you're probably comatose, and by six hours, without an antidote, you are dead.


When feeling very threatened, the Black Mamba usually delivers multiple strikes, injecting its potent neuro- and cardiotoxin with each strike, often attacking the body or head, unlike most other snakes. It can strike up to 12 times in a row. A single bite from a Black Mamba can inject enough venom to kill up to 10-25 grown men, easily killing one unless the appropriate anti-venom is administered in time. When cornered, it will readily attack. When in the striking position, the mamba flattens its neck, hisses very loudly and displays its inky black mouth and fangs. It can rear up around one-third of its body from the ground, which allows it to reach heights of approximately four feet.
In the past, the mortality rate for a Black Mamba bite was nearly 100%, the highest among venomous snakes. Now, because of the development of effective antivenin in Africa, the rate has been decreased to 75% (25% of bite victims now receive antivenin in time to be effective). Depending on the nature of a bite, death can result in as little as 30 minutes or it may take up to 120-180 minutes.




3. Inland Taipan
Inland Taipan, the most toxic venom of any snake in Australia. Maximum yield recorded (for one bite) is 110mg. That would porbably be enough to kill over 100 people or 250,000 mice. With an LD50 of 0.01 mg/kg, it is about 10 times as venomous as a Mojave rattlesnake and 750 times as venomous as a common cobra. The Fierce Snake is native to the arid regions of central Australia, extending from the southeast part of the Northern Territory, and into west Queensland.


The Fierce Snake or Inland Taipan can also be found north of Lake Eyre and to the west of the split of the Murray River, Darling River and Murrumbidgee River. Fierce Snakes are known to live in holes, and feed on small rodents such as mice and rats.
Despite its name, Fierce Snakes are not known to be particularly aggressive, but docile. They will strike if provoked, however, injecting their incomparably toxic venom. No fatalities have been attributed to this species, and all known bites have been to people who keep them in captivity or actively seek them out in the wild.




4. Atheris hispida
Found in the rain forests of Central Africa, this small but highly venomous viper is noted for its huge eyes and keeled, bristle-like scales which give it an almost feathered appearance (hence one of its common names, ”feathered tree viper”). Atheris vipers grow up to 75 cms long, with males being longer than females (unusual among snakes).  

Like all vipers, Atheris has long, retractable fangs in the front of its upper jaw; there is no known antidote to its venom, which causes blood clotting difficulties, pain and swelling, and often, death. Fortunately, these vipers usually live far away from human settlements, and therefore Atheris bites are exceedingly rare.




5.  Coral Snake
The coral snakes are a large group of elapid snakes that can be found in North America. Coral snakes vary widely in their behavior, but most are very secretive, fossorial snakes which spend the vast majority of their time buried in the ground or in leaf litter of a rainforest floor, only coming to the surface during rains or during breeding season.
Some species, like Micrurus surinamensis are almost entirely aquatic and spend most of their lives in slow moving bodies of water that have dense vegetation. Like all elapid snakes, coral snakes use a pair of small fangs, which are fixed in the front of their top jaw, to deliver their venom. Due to the time it takes for the venom take effect, coral snakes have a tendency to hold on to a victim when biting, unlike vipers which have retractable fangs and tend to prefer to strike and let go immediately.  

Coral snakes are not aggressive or prone to biting however, and account for less than a single percent of the number of snake bites each year in the United States. Most coral snake bites occur because of accidental handling of the snake while engaged in an activity like gardening. Due to the small size of coral snakes, along with their having much smaller fangs than pit vipers, bites are frequently ineffective and have some difficulty penetrating shoes or even thick clothing. This along with the fact that coral snakes are quite shy and reclusive makes bites quite rare.
However, coral snakes are highly venomous, being the only relative of the cobra found in the New World. Despite their relatively small size, their venom is a powerful neurotoxin, quite capable of killing an adult human. Any bite from a coral snake should be considered life threatening and immediate treatment should be sought.




6.  Saw Scaled Viper
Echis carinatus or Saw Scaled Viper is a venomous viper species found in parts of the Middle East and Central Asia, and especially the Indian subcontinent. It is the smallest of the Big Four dangerous snakes of India. Five subspecies are currently recognized, including the typical form described here.
This species is mostly crepuscular and nocturnal, although there have been reports of activity during daylight hours. During the daytime they hide in all kinds of places, such as deep mammal burrows, rock fissures fallen rotted logs.  

In sandy environments, they may bury themselves leaving only the head exposed. Often, they are most active after rains or on humid nights. When alarmed, they put on a distinctive threat display. They move about mainly side winding: a method at which they are considerably proficient and alarmingly quick. They are also capable of other forms of locomotion, but side winding seems to be best suited to moving about in their usual sandy habitats. It may also keep them from overheating too quickly, as they leave only two points of contact with the hot surface.
This species is often found climbing in bushes and shrubs, sometimes as much as 2 m above the ground. When it rains, up to 80% of the adult population will climb into bushes and trees. Once, it was observed how some 20 individuals had massed on top of a single cactus or small shrub.




7. Death Adder
Death Adder can be found in Australia and New Guinea. They are very viper-like in appearance, having triangular shaped heads and small subocular scales. They also have vertical pupils and many small scales on the top of the head. Like vipers, they have short, fat bodies normally 50 – 90 cm (20 – 36 inches) long. Their fangs are also longer and more mobile than for most other elapids, although still far from the size seen in some of the true vipers. Despite their name and appearance, they are not vipers at all, but elapids (like all Australian venomous snakes).
This is a case of convergent evolution. Death adders inject on average 40 – 100 mg of extremely toxic venom (0.4 – 0.5 mg/kg murine LD50, subcutaneous) with a bite. This makes an untreated death adder bite one of the most dangerous in the world (rated in top 10 in the CSL list). 

Death adder venom is highly neurotoxin. It blocks the post-synaptic neuromuscular transmission from the acetylcholine receptor. Unlike other snakes of its type, it does not contain either procoagulants or myolysins, making treatment easier. A bite from a death adder causes paralysis. While this paralysis is very minor at first, it can cause death from a complete respiratory shutdown in as little as six hours.
Symptoms peak in 24 – 48 hours. Symptoms of envenomation can be reversed through the use of death adder anti-venom, or using anticholinesterases, which break the synaptic blockade by making acetylcholine more available to the brain. Before antivenom was introduced, 50% of death adder bites were fatal. Now, with the anti-venom, and due to the slow progression of envenomation symptoms, fatalities from death adder bites are very rare in Australia. In New Guinea, deaths from these snakes are still common.




8. Bushmaster

The Bushmaster, lachesis muta muta is the largest Pit Viper in the world with a nasty reputation as a "cruel dude". The Bushmaster is a huge, thick-bodied and highly venomous snake with a triangularly shaped head, one of nature's warning signs that a snake is poisonous and potentially deadly. Bushmasters live in remote, heavily forested tropical jungle terrain. Isolated in their jungle environment, envenomation by a Bushmaster is very serious, sometimes fatal and particularly dangerous to humans.
Bushmaster is the largest venomous snake in the New World, often reaching lengths in excess of 6 feet with a maximum recorded length reaching an amazing 14 feet! It can be found in tropical forested areas throughout Central and South America.  

The Bushmaster has earned this fierce reputation, known to aggressively attack man but only few human attacks have been recorded due primarily to the Bushmaster's nocturnal nature. Even if they do attack only occasionally, the Bushmaster is greatly feared by people indigenous to their jungle habitat.
Appropriately named in English, the name Bushmaster when translated from Latin means "Brings Silent Death". One of the largest and most dangerous snakes in South America, the Bushmaster is capable of multiple bite strikes, injecting large amount of venom and even the bite of a juvenile Bushmaster can be fatal. The Bushmaster is the largest Pit Viper in the world. This snake has a triangular shaped head with rough scales.




9. Sea Snake
This is a species of sea snake.It is found in the Arabian Sea and Persian Gulf of Oman, south of the Seychelles and Madagascar, the seas of South Asia (Pakistan, India and Bangladesh), Southeast Asia , Myanmar (formerly Burma), Thailand, Vietnam), Australia (Northern Territory and Queensland) and New Guinea.
Sea snakes are easily the most unusual of all snakes. They belong to the same family as cobras and coral snakes (Elapidae), but they have adapted to a completely marine lifestyle; in some species, the adaptations are simply incredible.  

There are 62 species recognized to date, and they are found in the Pacific and Indian Oceans; they are all extremely venomous, with some species, such as the Beaked Sea Snake, having venom up to ten times more powerful than a cobra’s. One sea snake species, the Belcher’s sea snake, is considered by experts to be the most toxic of all snakes, marine or otherwise. Fortunately, sea snakes are usually docile and human fatalities are exceedingly rare.
Most sea snakes give birth to live young; this means that they don’t have to return to a beach to lay eggs as sea turtles do (except for a few species). As a result, they have practically lost the broad scales on their belly, which other snakes use to move on land, and most sea snakes are completely helpless out of the water.


10.  Malayan or Blue Krait
In Southeast Asia and Indonesia, 50% of the bites from this snake are fatal even with the use of antivenin treatment. Kraits are ophiophagous, preying primarily upon other snakes (including venomous varieties) and are cannibalistic, feeding on other kraits. They will also eat small lizards. 


All kraits are nocturnal. The snake is more docile during the daylight hours, becoming more aggressive during the night. However, they are rather timid and will often hide their heads within their coiled bodies for protection. When in this posture, they will sometimes whip their tail around as a type of distraction.




11. Tiger keelback
Also known as yamakagashi, or Japanese water snake, this species is found mostly in Eastern Asia. It is small, rarely exceeding one meter in length, and very shy, so much in fact that they were considered to be harmless for a long time, until someone died of a yamakagashi bite in the 80s.
Fortunately, due to their docile temperament, these snakes are very unlikely to bite and fatalities remain exceedingly uncommon. Also, since their venomous fangs are located in the rear of the jaws, they can’t inject their venom as easily as other snakes.  

They feed mostly on frogs and toads. Other than their bright colors, Tiger Keelbacks look kind of normal; however, they have a very interesting defense mechanism. Recently, it was discovered that these snakes feed on poisonous toads; not only are they immune to the toad’s poison, but they can actually ”sequester” this poison and store it in a couple glands they have in the neck. When threatened, the snake releases the toad’s poison from its neck glands. This amazing adaptation not only protects the snake from most predators, but also allows it to save its own venom for hunting instead of wasting it on something too big to eat!  Article Source: wikipedia & web

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