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Fatalities, fangs, venom, teeth, prey, ecosystems, species

In USA, an average of five fatalities from snake envenomation are reported annually (Gold et al., 2002)1. These deaths are a consequence of approximately 8000 recorded bites from venomous species. The true number of bites is closer to 45000 according to (Litovitz et al., 1997)2, which estimates unreported cases too.

Also, according to statistics, 18 percent of all bites are from venomous species, and the Copperhead Snake is the snake responsible for most envenomations.

Worldwide, India is the country most affected with around 35000 to 50000 yearly fatalities due to snake bites, and Pakistan comes second with approximately 8200 fatalities (Alirol et al. 2010)3.

Snake fangs

The different species of snakes have their fangs curving in three dissimilar but typical patterns. Ducts inside the fang connect the fangs to the venom glands, which are the red areas on the photos - where the production of venom takes place.

Skull from a typical Elapid snake

Skull from an Elapid snake.
E.g. Cobra and Sea Snake

 Skull from a typical Elapid snake

Skull from a Viperid snake.
These are pit-vipers.

 Skull from a typical Rear-fanged snake

Skull from a Rear-fanged snake.
Often not very venomous.

Swallowing prey

Snakes can consume prey significantly wider than their own diameter. This phenomenon is commonly referred to as jaw-walking.

Snakes jaws attach only loosely to their skulls and as unconnected they can work independently. That is, the two sides can collaborate on pulling the animal inward.

By alternating the two actions, keeping a grip and pulling, swallowing large animals is possible; having elastic skin is a prerequisite.

Snakes teeth

Swallowing animals would be difficult without teeth. Snakes teeth are curved and their help to pull the animal further into the mouth. The photograph is a jaw from a Diamondback Rattlesnake, and it is courtesy of the American Museum of Natural History. Larger snakes have longer teeth as they often have to penetrate feathers to consume prey closer to their own size. The Diamondback Rattlesnake on the photo from the museum has rather short teeth.

Jaw from a Diamonback Rattlesnake with small teeth





Lightning kills more people than venomous snakes

Injuries caused by venomous snakes are rare. When compared to the number of people killed by lightning, which in 1959-1994 was 0.42 people per million (Curran et al., 1994)4, snake envenomations suddenly seem insignificant.

Australia's venomous snakes

Sutherland (1992)5 studied Australian snake bite fatalities over a 10 year period. Only 18 snake bites had a deadly outcome in that period. The author acknowledges that all fatalities may not be included in the available set of data.

Africa's venomous snakes

Puff Adders, as one reader noted, are the snakes responsible for most fatalities in Africa. This site also describes the Boomslang (a very Afrikaans word), the Gaboon Viper, the Black Mamba, and the Death Adder among the venomous snakes of Africa.

South and Central America and their venomous snakes

In South and Central America, bites from venomous snakes are more common than in the US. In Costa Rica, the annual number of hospital admissions due to snake envenomations is 22.4 per 100000 inhabitants (Rojas et al., 1997)6.

Table with venomous snakes from all continents, except Antarctica

North America South America Australia/Oceania Africa Asia Europe
Copperhead Bushmaster King Brown Snake Russel's Viper Saw-scaled Viper Common Adder
Cottonmouth Rattlesnakes Brownsnakes Olive Whip Snake Krait Long-nosed adder
Rattlesnakes Coral Snake Taipan Snake Puff Adder Cobra Snake Pallas Viper
Coral Snake Fer de Lance Tiger Snake Boomslang Ursini's Adder
Sea Snake Death Adder
Black Mamba Snake
Gaboon Viper
Green mamba
Copperhead snake

Snakes in ecosystems

Snakes serve an important role as predators in ecosystems, and snakes healthy ecosystem are often abundant in a variety of predators such as snakes that maintain populations of rodents and other animals at acceptable levels. Just think of farmers and the problems they have with rodents. Snakes are actually responsible for keeping crop yields high, and for preventing the spreading of diseases.

References

1 Gold, BS et al. "Bites of Venomous Snakes". New England Journal of Medicine Vol. 347, No. 5 pp. 347-356 (2002)
2 Litovitz TL et al. "Annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System" Am J. Emerg Medicine 15, pp. 447-501 (1997)
3 Alirol et al."Snake Bite in South Asia: A Review", PLOS NEGLECTED TROPICAL DISEASES, Vol. 4(1) pp. 1-7 (2010)
4 Curran EB. et al. "Lightning injuries and Damage Reports in the United States from 1959-1994" (1997), NOAA Technical Memo-randum
5 Sutherland SK "Fatalities from Snake Bite in Australia, 1981-1991", MED. JOURNAL OF AUSTRALIA 157 Vol. 11-12. pp. 740-746 (1992)
6 Rojas G et al. "Snakebite mortality in Costa Rica", Toxicon, Vol. 35 pp. 1639-43 (1997)

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