Episode 144 – Horned Viper: The Vied Viper

Today, in the podcast, we talk about the horned viper and sidewinding!

“…and today we’re talking about an animal that has adapted to a legless lifestyle in an arid region. But more on that later.”

Cursed to crawl on their bellies, snakes have taken to the limbless life with seemingly listless languid movement. But these apparently listless articulations of their sinuous bodies, are done with great intention. Snakes are able to slither almost everywhere. Without claws, legs, or arms that can climb trees, slide across the ground, and some can even glide on the air. But the horned viper is posed with a particular challenge in the form of soft shifting sand. But laudable locomotion is an interesting way a serpent can make its way through Life, Death, and Taxonomy. 


  • Saharan horned viper
  • Desert Horned Viper
  • The Vied Viper
  • Spiny Serpent
  • Cleopatra’s Curse
  • Que Cerastes Cerastes

Description of the Horned Viper

  • It has a short, thick body (for a snake)
  • Where a lot of snakes are smooth and shiny, the horned viper (and most vipers) have raised, matte finish scales. They look spiny.
  • The head is wide and flat like a cookie that not quite finished baking
  • On top of that head, there are two scales that stick straight up over the eyes – like horns
  • The scales are mottled shades of tan to mimic sand with darker blotches running down the length

Measure Up

Welcome to the beloved Measure Up segment. The official listener’s favorite part of the show! The part of the show when we present the animal’s size and dimension in relatable terms through a quiz that’s fun for the whole family. It’s also the part of the show that’s introduced by you when you send in audio of yourself saying, singing, or chittering the words “measure up” into ldtaxonomy at gmail dot com. We don’t have a new measure up intro this week! That means we get to hear from an animal and Carlos has to guess what it is.

  1. Saltwater crocodile
  2. hamadryas baboon
  3. American Bison
  4. My Rumbly Tummy


  • 30–60 cm (12–24 in)
  • How many horned vipers go into the longest ever noodle?
  • Hint: The record was achieved by the Xiangnian Food Co in China in October of 2017. There is a video on the Guinness record page!
  • 5,059 snakes. The noodle was 3,084 m (10,119 ft 1.92 in).

Venom Lethality

  • LD50 0.4 mg/kg (Intravenous) and 3.0 mg/kg (subcutaneous)
  • How many more times is horned viper venom toxicity than the toxicity of caffeine?
  • Hint: Toxicity can vary widely from person to person depending on many factors. The number we’re working with involves oral testing on albino lab rats. In humans, the lethal dose can be lower or higher depending on health conditions, sensitivities, and other factors. 
  • Viper venom is about 122 times more deadly than caffeine. The LD50 of caffeine is 367 mg/kg. But it could be as low as 150 mg in humans. 

Fast Facts About the Horned Viper

  • Range: Lives in the deserts of Northern Africa and the Middle East all the way from Morocco and Somalia to Yemen and Qatar.
  • Diet: eats lizards, small mammals, and birds. Basically whatever it can find in the desert.
  • Behavior:
    • He’s an ambush predator and blends in with the sand at night to snap up unsuspecting prey. During the day, he hangs out in burrows or under rocks to avoid the heat.
    • Can produce a raspy warning sound by rubbing its scales together
    • Gets water in the desert through the dew that condensates on its scales
  • Lifespan: 10-15 years
  • Predators: Sand Cat and large predatory birds
  • Venom: Getting bit is not fun. It injects its victims with 13 different toxins that cause swelling, pain, excessive bleeding, nausea, sweating, fatigue, kidney failure, and heart irregularities. Some describe the feeling of having their heart squeezed by a hand.
  • In Shakespeare’s play Antony and Cleopatra, she uses a horned viper to kill herself at the end

Horned Viper Major Fact: Slippery Sidewinders 

Without legs, snakes have to rely on complex movement to handle different environments. Limb allows many animals to standardize their locomotion. For instance, humans just put one foot in front of the other in most environments. But snakes need to adopt several styles to deal with different terrains. 

There are four types of locomotion that are associated with snakes.

  1. Serpentine – The typical snake style. This is when the snake moves bake and fourth in an S-shape. This method involves pushing off of a solid object and pushing of bends in the body. The need to bend the body to form an anchor point gives this method the signature S-shape.
  2. Concertina – This involves two anchor points, one in the front of their body and one in the back. The reach by anchoring the back of their body and then anchor the front of their body to pull the rest up. This creates an accordion or inch-worm movement.
  3. Rectilinear – This looks the most like gliding along the ground. Rectilinear movement allows snakes to move when there isn’t enough room to articulate their body, like on a narrow ledge. This method involves moving their belly skin with special muscle groups to bunch it up and then push forward. 
  4. Sidewinding – Sidewinding may be the most complex movement, and it serves two major functions. Sidewinding involves several points of contact with the ground and lateral movement instead of forward movement. Desert sidewinders might create a track in the sand where they move forward and then lift their body up and sideways to create a new track that’s parallel to the old one, almost like a staircase. It might also involve a scrunched up S-shape where the snake’s head is pointed to their side and three points of contact walk them forward. 

Why Sidewind?

The desert horned viper is the most common sidewinder, but this method is used by several snakes from completely different parts of the world, especially in sandy deserts. But other snakes like members of the family Homalopsine in Asia use it while traversing mud flats. The common denominator seems to be unstable ground. 

Other methods of snake movement mild causes the practitioner to be stuck in place with shifting sand or slide down unstable slopes. Sidewinding increasing their point of contact with the ground to make for a more stable climb up sandy terrain. Instead of sliding along shifting ground, their points of contact are static and the forward momentum comes from lifting their body to  a new point of contact. 

This also has another benefit in arid desert climates. 

Keeping Cool

Because sidewinding is sort of like walking where the body is lifted up by stable points of contact, more of their belly is lifted away from the ground than it would be with the other locomotion methods. This can allow them to make less contact with hot sand, mitigating the likelihood of overheating or burning themselves. 

Ending: So drink from your scales, stay anchored, and sidewind your way to happiness like the horned viper here in LDT