Scientific Classification

Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata

Conservation Status

Range and Population

approximately 190 species


Vipers' habitats vary across their nearly worldwide range. They live in mountains, rainforests, fields and deserts


Roughly 18 years in captivity


Horned Viper: 50 – 70 cm Lachesis: 30 cm Causus rhombeatus: 10 – 12 cm


  • Vipers are a family of venomous snakes found everywhere except Oceania, the Antarctic, and some isolated islands.
  • They have long, hinged, hollow fangs that are good for penetration and for venom injection.
    • This is one of the most sophisticated venom-injections systems in the snake world. Their fangs can be folded back when not in use. They just kinda sit along the roof of of the mouth.
    • This means that the teeth can grow larger than they would if they were always pointing down.
  • Their Latin name vipera, roughly means live birth.
  • Another common feature of vipers is that they have elliptical pupils.
  • They generally have keeled scales, this means that they overlap. Their skin is not smooth like in other snakes.


  • Their venom glands are located behind their eyes.
  • When they attack, their mouth can open 180 degrees.
  • When they bite down the muscles around the glands squeeze the venom out, and that’s when you get in trouble.
    • They’re also capable of biting without injecting venom. This is called a dry bite and it’s used mostly for self defence. 
    • The snake doesn’t necessarily want to use its venom unless it’s necessary. They have a finite amount of venom, and once it’s depleted it takes a while to replenish. 
  • Their distinct triangular head is due to the location of their venom glands.
  • Their venom is generally different than other snakes. 
    • Cobras and other elapids have venom full of neurotoxins that cause muscle contraction and paralysis. This affects the diaphragm, which causes the victim to asphyxiate. 
    • But viper venom attacks the blood. Blood that has touched viper venom loses the ability to coagulate, so the wound keeps bleeding much longer than usual. This is accompanied by pain and swelling, and in some cases necrosis. (If you want to lose your appetite google “viper necrosis”)
    • The venom also helps with digestion. It starts breaking down proteins before the snake swallows its prey.
    • Eventually the prey dies due to a collapse in blood pressure.
    • Warm weather vipers tend to have more potent venom than moderate weather vipers.
    • DISCLAIMER: These are general terms. Some vipers have neurotoxin venoms, and some elapids have venoms that attack the blood.
  • Some vipers, the Pit Vipers, have heat-sensing  pits between their eyes and nostrils.



  • Vipers are mostly nocturnal, sluggish snakes.
    • Most of them have good camouflage and spend most of their time hiding.
  • Vipers can gage the size of the prey or the attacker and determine how much venom needs to be used.
  • Because their venom takes longer to immobilize the prey than elapid venom, they usually have to follow their prey for a while after the bite. This is called “prey relocalization”
    • They can smell their own venom and follow the scent. Of course, the problem with this is that it can attract other vipers.
    • But the positive side of it is that it allows them to bite-and-release larger and potentially dangerous prey.
  • Other than when hunting or defending themselves, vipers are chill. The shape of their head makes them look more sinister than they are.
  • They’re ambush predators so they don’t a lot of moving until a prey item is close enough for them to strike.
    • Once it’s close enough they can strike in a quarter of a second.


Vipers We Think Are Cool

  • Pit Vipers
    • Pit vipers are cool because they have a heat-sensing organ, which basically gives them heat vision.
    • All the vipers in the Americas are pit vipers.
    • They use this organ to find warm blooded prey such as mice and birds (many vipers are arboreal)
    • When infrared radiation falls into the holes, the snake can find the source of the radiation by sensing which side received more. (pretty much the same as our directional hearing). It’s basically 3d infrared vision.
    • Experiments have shown that even when deprived of their senses of smell and vision, they can accurately find prey that’s just 0.2 degrees warmer than the background.
    • Because a lot of vipers are nocturnal, this 6th sense combined with their chemoreception gives them a great ability to find prey in the dark.
    • Pit Vipers are very diverse. There are are over 150 different species and they range in size from 30 cm to 360 cm.
  • Rattlesnakes
    • The coolest kind of pit viper is the rattlesnake.
    • Rattlers are found only in the Americas, and range from central Canada to Argentina.
    • Obviously the cool thing about them is their rattle.
      • It’s a warning signal against potential predators.
      • They’re modified scales, and become hollow interlocked segments.
      • They’re made of keratin,-the same material as hairs, nails, and horns. 
      • When the snake shakes its tail the segments vibrate against each other and make the rattling noise. The noise gets amplified because the segments are hollow.
      • They can shake it 50 times a second and sustain the shaking for 3 hours.
      • When babies are born they can’t rattle. It takes them 2 sheds to develop the hardened tip required for rattling.
      • Rattlers travel with their tail pointing up to protect it from rocks. But the tips break off often. But in general terms, the longer the rattle, the older the snake.
  • Bush Vipers
    • Bush vipers are African pitless vipers. 
    • They’re found in the rainforests and woodlands of South-Saharan Africa, but not in the southern tip of the continent.
    • They’re tree snakes and come in a lot of different colours, but green is the most common coloration.
    • Their scales are very keeled, that’s what gives them a badass rough look. 

Interesting Facts

  • There 19 types of viper in North America, 3 in Canada. 
    • The Canadian vipers are the Massasauga rattlesnake, the Pacific rattlesnake, and the prairie rattlesnake. Next time you go to Georgian Bay keep in mind that you’re in viper country.
    • Of the 10 most venomous snakes in the US, 9 are vipers. 7 are rattlesnakes and the other 2 are the cottonmouth and the copperhead. 2 of them, the Prairie rattler and the Pacific rattler, also live in Canada.
  • Some species of viper that live in colder climates brumate. That’s the reptilian version of hibernation.
    • Sometimes they get together to brumate in groups of up to 1000 snakes.
    • This is called a viper den. Vipers like to return to the same den every year and sometimes share it with other animals such as turtles.
  • Similarly, in the summer they aestivate, which is a kind of dormancy where they remain very quiet to prevent overheating and to conserve water.