Dangerous Critters

In certain forums on the web we find lists purporting to rank the most dangerous and/or venomous snakes in the world. Unfortunately one can take one's pick as there are a number - and none of them agree with each other.

How accurate are they? How long is a piece of string?

The criteria for judging the most dangerous snakes should be simple. In fact only one factor can legitimately be used - human deaths attributed to the specific species.

Contributing factors would be the distribution of the species, aggression, venom yield, toxicity of venom, habits of the snakes.

Obviously a fairly venomous species that is found in vast reaches of the earth will kill more humans than a violently venomous species known to live on only one inaccesible grassy knoll on an uninhabited Patagonian island.

However when all is said and done - the only accountable factor MUST be the body count of the species.

As to the most venomous we run into similar problems of definition. The effect of snake venom is measured in mouse units. The standard test is to measure how many standard sized mice a given weight/volume of venom will kill. From there an estimation and extrapolation is made to a standard 70 kg human male.

The problems inherent here are:

venoms differ in their specific effects
venoms are often far more lethal to specific prey animals
venoms vary by area distribution, age, sex, time and season in their toxicity.
the yield varies from specimen to specimen.

Fierce Snake Australia's crop of highly venomous elapids feature high on many lists. Yet Australia has had, over the last 20 years, a confirmed mortality rate averaging less than 2 per annum and a guestimated maximum of 3.1 per annum. (These are people who die from snakebite in remote places and where medical science does not make a diagnoses).
This translates, roughly, to a mortality rate of 1:8 million per annum. Distributed roughly among 16 highly venomous snakes. Average per species thus is 1 fatality per snake species every 8 years. The vaunted "most venomous snake on earth" the Fierce Snake (Oxyuranus microlepidotus) has yet to be implicated in a single fatality. The range of the snake is small and the population extremely thin. So despite the fact that an average yield of venom from this snake can kill 250 000 rats, just how dangerous is it?

Russell's Viper On the other hand the humble Russell's Viper kills humans by the hundreds. It seldom if ever figures in the "most dangerous snake" lists! The Cobras of Sri Lanka kill an average 5 people out of every 100 000 population per annum. Translated to the Australian scenario this would mean around 900 deaths per annum.
What these lists are giving us is the POTENTIALLY most dangerous snakes. A true list of the most FATAL TO MAN snakes would give us some very humble but widespread and moderately venomous snakes.

So what's the answer?

There is none - only an answer within defined parameters such as:

The snakes with the largest venom yield
The snakes with the most toxic venom to mice
The snakes that have killed the most humans

So who are the leading contenders?

This list is by no means complete.

Snake Symptoms Mortality Treatment

Asian pit vipers - from 2 to 5 ft. long, throughout Asia reactions and mortality vary, but most bites cause tissue damage and mortality is generally low.

Australian brown snakes - 4 to 7 ft. long very slow onset of cardiac or respiratory distress moderate mortality, but because death can be sudden and unexpected, it is the most dangerous of the Australian snakes antivenom.

Barba Amarilla or Fer-de-lance - up to 7 ft. long, from tropical Mexico to Brazil severe tissue damage common moderate mortality antivenom.

Black mamba - up to 14 ft. long, fast-moving, S and C Africa rapid onset of dizziness, difficulty breathing, erratic heart-beat mortality high, nears 100% without antivenom. antivenom.

Boomslang - under 6 ft. long, in African savannahs rapid onset of nausea and dizziness, often followed by slight recovery and then sudden death from internal hemorrhaging bites rare, mortality high antivenom.

Bushmaster - up to 12 ft. long, wet tropical forests of C and S America few bites occur, but mortality rate is high.

Common or Asian cobra - 4 to 8 ft. long, throughout S Asia considerable tissue damage, sometimes paralysis mortality probably not more than 10% antivenom.

Copperhead - less than 4 ft. long, from New England to Texas pain and swelling very seldom fatal antivenom seldom needed.

Coral snake - 2 to 5 ft. long, in Americas south of Canada bite may be painless, slow onset of paralysis, impaired breathing mortalities rare, but high without antivenom and mechanical respiration. antivenom.

Cottonmouth water moccasin - up to 5 ft. long, wetlands of southern U.S. from Virginia to Texas. mortality low, but tissue destruction can be extensive antivenom.

Death adder - less than 3 ft. long, Australia rapid onset of faintness, cardiac and respiratory distress at least 50% mortality without antivenom. antivenom

Desert horned viper - in dry areas of Africa and western Asia swelling and tissue damage low mortality antivenom.

European vipers - from 1 to 3 ft. long bleeding and tissue damage mortality low antivenoms.

Gaboon viper - over 6 ft. long, fat, 2-inch fangs, south of the Sahara massive tissue damage, internal bleeding few recorded bites. antivenom.

King cobra - up to 16 ft. long, throughout S Asia rapid swelling, dizziness, loss of consciousness, difficulty breathing, erratic heartbeat mortality varies sharply with amount of venom involved, most bites involve nonfatal amounts antivenom.

Kraits - up to 5 ft. long, in S Asia rapid onset of sleepiness, numbness up to 50% mortality even with antivenom. antivenom

Puff adder - up to 5 ft. long, fat, south of the Sahara and throughout the Middle East rapid large swelling, great pain, dizziness moderate mortality often from internal bleeding antivenom.

Rattlesnake - 2 to 6 ft. long, throughout W. Hemisphere. Rapid onset of severe pain, swelling mortality low, but amputation of affected digits is sometimes necessary Mojave rattler may produce temporary paralysis. antivenom.

Rinkhals, or spitting, cobra - 5 ft. and 7 ft. long, S Africa squirt venom through holes in front of fangs as a defense venom is severely irritating and can cause blindness. antivenom.

Russell's viper or tic-polonga - over 5 ft. long, throughout Asia internal bleeding moderate mortality rate, bite reports common antivenom.

Saw-scaled or carpet viper - up to 2 ft. long, in dry areas from India to Africa severe bleeding, fever high mortality, causes more human fatalities than any other snake antivenom.

Sea snakes - throughout Pacific, Indian oceans except NE Pacific almost painless bite, variety of muscle pain, paralysis mortality rate low, many bites are not envenomed some antivenoms.

Sharp-nosed pit viper or One Hundred Pace Snake - up to 5 ft. long, in S Vietnam and Taiwan, China the most toxic of Asian pit vipers, very rapid onset of swelling and tissue damage, internal bleeding moderate mortality antivenom.

Taipan - up to 11 ft. long, in Australia and New Guinea rapid paralysis with severe breathing difficulty mortality nears 100% without antivenom. antivenom.

Tiger snake - 2 to 6 ft. long, S Australia pain, numbness, mental disturbances with rapid onset of paralysis may be the most deadly of all land snakes though antivenom is quite effective. antivenom.

Yellow or Cape cobra - 7 ft. long, in southern Africa most toxic venom of any cobra, rapid onset of swelling, breathing and cardiac difficulties mortality high without treatment antivenom.

Note: Not all bites by venomous snakes are actually envenomed.
All animal bites, however, possibly carry tetanus, and anyone suffering a snake bite should seek medical attention.
Antivenoms do not cure they are only an aid in the treatment of bites.
Mortality rates above are for envenomed bites

Snake	Symptoms	Mortality	Treatment
Asian pit vipers - from 2 to 5 ft. long, throughout Asia		reactions and mortality vary, but most bites cause tissue damage and mortality is generally low.
Australian brown snakes - 4 to 7 ft. long	very slow onset of cardiac or respiratory distress	moderate mortality, but because death can be sudden and unexpected, it is the most dangerous of the Australian snakes	antivenom.
Barba Amarilla or Fer-de-lance - up to 7 ft. long, from tropical Mexico to Brazil	severe tissue damage common	moderate mortality	antivenom.
Black mamba - up to 14 ft. long, fast-moving, S and C Africa	rapid onset of dizziness, difficulty breathing, erratic heart-beat	mortality high, nears 100% without antivenom.	antivenom.
Boomslang - under 6 ft. long, in African savannahs	rapid onset of nausea and dizziness, often followed by slight recovery and then sudden death from internal hemorrhaging	bites rare, mortality high	antivenom.
Bushmaster - up to 12 ft. long, wet tropical forests of C and S America		few bites occur, but mortality rate is high.
Common or Asian cobra - 4 to 8 ft. long, throughout S Asia	considerable tissue damage, sometimes paralysis	mortality probably not more than 10%	antivenom.
Copperhead - less than 4 ft. long, from New England to Texas	pain and swelling	very seldom fatal	antivenom seldom needed.
Coral snake - 2 to 5 ft. long, in Americas south of Canada	bite may be painless, slow onset of paralysis, impaired breathing	mortalities rare, but high without antivenom and mechanical respiration.	antivenom.
Cottonmouth water moccasin - up to 5 ft. long, wetlands of southern U.S. from Virginia to Texas.		mortality low, but tissue destruction can be extensive	antivenom.
Death adder - less than 3 ft. long, Australia	rapid onset of faintness, cardiac and respiratory distress	at least 50% mortality without antivenom.	antivenom
Desert horned viper - in dry areas of Africa and western Asia	swelling and tissue damage	low mortality	antivenom.
European vipers - from 1 to 3 ft. long	bleeding and tissue damage	mortality low	antivenoms.
Gaboon viper - over 6 ft. long, fat, 2-inch fangs, south of the Sahara	massive tissue damage, internal bleeding	few recorded bites.	antivenom.
King cobra - up to 16 ft. long, throughout S Asia	rapid swelling, dizziness, loss of consciousness, difficulty breathing, erratic heartbeat	mortality varies sharply with amount of venom involved, most bites involve nonfatal amounts	antivenom.
Kraits - up to 5 ft. long, in S Asia	rapid onset of sleepiness, numbness	up to 50% mortality even with antivenom.	antivenom
Puff adder - up to 5 ft. long, fat, south of the Sahara and throughout the Middle East	rapid large swelling, great pain, dizziness	moderate mortality often from internal bleeding	antivenom.
Rattlesnake - 2 to 6 ft. long, throughout W. Hemisphere. Rapid onset of severe pain, swelling	mortality low, but amputation of affected digits is sometimes necessary	Mojave rattler may produce temporary paralysis.	antivenom.
Rinkhals, or spitting, cobra - 5 ft. and 7 ft. long, S Africa	squirt venom through holes in front of fangs as a defense	venom is severely irritating and can cause blindness.	antivenom.
Russell's viper or tic-polonga - over 5 ft. long, throughout Asia	internal bleeding	moderate mortality rate, bite reports common	antivenom.
Saw-scaled or carpet viper - up to 2 ft. long, in dry areas from India to Africa	severe bleeding, fever	high mortality, causes more human fatalities than any other snake	antivenom.
Sea snakes - throughout Pacific, Indian oceans except NE Pacific	almost painless bite, variety of muscle pain, paralysis	mortality rate low, many bites are not envenomed	some antivenoms.
Sharp-nosed pit viper or One Hundred Pace Snake - up to 5 ft. long, in S Vietnam and Taiwan, China	the most toxic of Asian pit vipers, very rapid onset of swelling and tissue damage, internal bleeding	moderate mortality	antivenom.
Taipan - up to 11 ft. long, in Australia and New Guinea	rapid paralysis with severe breathing difficulty	mortality nears 100% without antivenom.	antivenom.
Tiger snake - 2 to 6 ft. long, S Australia	pain, numbness, mental disturbances with rapid onset of paralysis	may be the most deadly of all land snakes though antivenom is quite effective.	antivenom.
Yellow or Cape cobra - 7 ft. long, in southern Africa	most toxic venom of any cobra, rapid onset of swelling, breathing and cardiac difficulties	mortality high without treatment	antivenom.

low mortality, up to 2% result in death
moderate, 2-5%
high, 5-15%.

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