Venomous snakes have been subject to mythology, tales and great prejudice. But the animals that strike fear in most humans are worth-shipped as gods in other cultures. In reality, they just very and shy and specialized predators.
Although we are always afraid of coming across a venomous snake that will charge us to death, the chance of this happening is actualy virtually non-existent.
Venomous snake, like most animals, are very shy and have never actively charged a human, simply because they are too afraid of us. Furthermore, there are a little more than 3000 snake species distributed all over the world, roughly 600 of them are venomous. However, only about 200 of all venomous snakes are considered medically important, and the chance of being killed by one is very small since antivenin is readily available around the world.
In this article, I want to explain how these animals are classified and distributed and how you can tell the different classes apart. As a little bonus, I will include an updated list of the 10 most venomous snake species of the world at the end. The classification of snakes is still subject to change and research, but I will do my best to keep the lists up to date.
The larges species complex of snakes are the Colubrid snakes (Colubridae). More than half of all the snake species in the world (1700) are Colubrids. Most of them are completely harmless snakes and only a small portion is considered venomous and almost all are medically unimportant.
The largest species complex of “true” venomous snakes are the Elapids (Elapidae). The family of sea snakes (Hydrophiindae) is now a seperate family and used to be a subfamily of the Elapinae. The last large group of venomous snakes are the Vipers (Viperidae), which are separated into 251 species, 33 Genera and four sub-families; Old World Vipers (Viperinae), New World or Pit Vipers (Crotalinae), Azemiops Vipers (Azemiopinae) and the Causinae.
In the following chapters I will explain the different families, what their traits are and how you can tell them apart.
The Viperidae family consist of 4 subfamilies, the Viperinae, Crotalinae, Causinae and Azemiopinae. All Vipers are rather stout bodied snakes and reach a length from only 35cm (Bitis peringuey) to over 2 m (Bitis gabonica, Lachesis muta, Protobothrops mangshanensis). They typically have a triangular shaped head and their anal scale is not divided. Vipers are a common subject in mythology and tales, which may be the reason why they are so feared. However, almost all Vipers are not very defensive and do not want to have anything to do with us humans (there are exception)
Viperidae Venom composition
Roughly 90% of the venom dry weight is protein, composed of a large variety of enzymes, polypeptide toxins and proteases. The enzymes include hydrolases (proteinases, endo- and exo- peptidases, phosphlipases) hyaluronidase and activators of inhibitors of the preys physiological mechanisms. Almost all venooms contain L – amino acid oxidases, phosophomono- and diesterases, phospolipase A2 and peptidases. Phospholipase A2 are the most wide spread of all snake venom enzymes, attacking mitochondria, red blood cells and leukocytes, peripheral nerve endings and skeletal muscles, causing haemorrhage, necrosis and flacid paralysis in their prey.
All Viperid venom act mostly hemotoxic and haemorrhagic, attacking both the prey clotting mechanism, causing tissue damage and persistent bleeding, or the victims blood pressure, causing the victim to die of shock, stroke or complete cardiac arrest. Although Viperid venom are relatively weak compared to some elapids, the composition of their venom makes a bite highly uncomfortable and extremely painful.
Viperidae Venom apparatus (Solenoglyphous Fangs)
Snakes mostly rely on their sense of smell to detect their prey. By regularly tasting the air with their tongue, they will recognize prey approaching and strike with precision even at night. Viperidae have the most advanced Fang and venom delivery system of all snake species, so-called solenoglyph fangs. As seen in the image, a Viper can fold their massive fangs back into their mouth. When they strike, they will open their mouth up to 160° wide and unfold their fangs. Like a needle, the fangs are hollow and directly connected to the venom gland to inject their prey with venom. This entire process goes down in less than a second. Sometimes, the animal may even realise that it has been injected with venom until it dies.
Viperidae – Old World Vipers (Viperinae)
First, there are called Old World Vipers or true Vipers because most of their species are distributed across the “Old World” (Africa, east and south-east Asia, Europe) and often look very “viperish”. They consist of 66 species distributed across 12 Genera. Generally, the Viperinae are short and stout bodies snakes with a characteristic triangular head shape and about 50cm – 120cm in length. Some species however, like the Gabon Viper (Bitis rhinoceros) can reach and impressive length of 2 m. These massive snakes are the largest of all Vipers, they have the longest snake fangs in the world (up to 5 cm when fully grown) and can deliver the largest quantity of venom (500 mg) of all snakes in one bite.
Old World Vipers are mostly ambush predators, which means that they can sit in the same spot for many days and wait their prey to pass by. Then, they will strike at an incredible speed and usually hold their prey in their jaws until it succumbs. Some smaller vipers like most European Vipers (Vipera) will let go of their prey after striking to avoid risking injury. All Vipers can strike at an incredible speed and will can bite, inject venom and release their prey in less than a second. Old World Vipers are seldom seen actively hunting or searching for prey. If a Viper is seen on the move, it may be changing its spot, basking for some energy in the sun, or on the lookout for a mate during mating season. Generally, a viper will flee if it notices a threat, such as humans approaching. However, if confronted it will hiss very loudly, puff its body up to look bigger and strike if the treat does not back off. Some Vipers have such good camouflage that they will trust it to conceal them completely and not move at all. Most accidents happen because people step on the snake they did not even see and get bit, which is neither the snakes, nor the humans fault.
Viperidae – New World Vipers (Crotalinae)
The New World Vipers or Pit Vipers consist of 151 species distributed across 18 genera. Like the Old World Vipers, they are mostly ambush predators, although some species are highly active hunters. Pit Vipers mostly hunt at night, where they also rely on their smell, but also highly on their Heat Pits, which give them their name. Heat Pit refer to the two holes on the front of their head (image below), close and similar to their nasal bits, but larger.
Inside these head pit are two highly sensitive membranes that detect changes in infrared radiation, much like a night-vision device. Like this, pit vipers are able to sense differences in heat radiation with up impressive 0.03° Celsius accuracy. This enables them to strike with incredible precision at their prey.
Like Old World Vipers, Pit Vipers are generally not very defensive and would rather be left alone. Some have developed highly interesting warning behaviors, like the commonly known rattlesnakes (Crotalus, Sistrurus). With every shed a rattle snake goes through, one piece of bone rattle is added to their tale to scare away potential threats.
Pit Vipers could be considered the ultimate predator since they have such highly advanced hunting mechanisms and strategies that enable them to hunt with a low failure rate.
Viperidae – Azemiop Vipers (Azemiopinae)
The Azemiopinae are a smaller group of Vipers endemic to southeast Asia. They include one Genus and two recognized species (Azemiops feae, Azemiops kharini). These species are very rare and hide deep in the jungle. Due to human activities, their vulnerable habitat is highly threatened.
Viperidae – Causinae
The Causinae are also a small species complex featuring only one Genus and six species, and are distributed all over Africa. They are often call false Vipers, because unlike most Vipers, they are slender and do not have a triangular head shape. However, their venom composition, genetic traits and Venom apparatus causes them to be classified as Vipers.
Elapids are the larges species complex of venomous snakes, formerly including two sub families, The Hydrophiinae (Sea snakes), and the Elapinae (land-bases elapids). Now the Hydrophiinae are recognized as an individual family but the are closely related. These snakes resemble Colubrid snakes, with their longs, slender bodies and a head that is not visually separated from the neck. Elapids feature many commonly known snakes like cobras, mambas and taipans and often have a reputation for being aggressive. However, this is just because elapids are very active during the day and often end up close to human settlements, causing frequent interactions that threaten the snake and provoke it to act defensively.
Elapids are front fanged venomous, or proteroglyphous. This means that their fangs are short, located at the font of their mouth cannot be folded like viper can. Some people often question whether elapids can even pierce the skin of their prey enough or bite through a jacked. The answer is no and yes, Elapids can indeed easily bite through a jecked. Just pierce your jacket with a short needle, it is almost the same and get get almost anywhere. And no, Elapids may not be able to sink their teeth in as deep as Vipers, but they do not need to since their venom composition is different
Elapid venom travels through the lymphatic system, which is located directly underneath the skin. Their venom also consist mainly of Enzymes such as Kunitz peptides, Acetylcholine inhibitors (Acetylcholinesterase) and alpha- and beta- neurotoxic Phospholipases A1 and A2. The largest group is probably made of neurotoxic three-finger peptides, which efficiently shut down the preys nervous system. An elapids Victim may die of shock, complete cardiac arrest due to flaccid paralysis or shut down of nervous system. Elapid toxins may be much more toxic than Viperid toxins, but the effects are not very painful in comparison. A sea snakes victim may succumb in less than 5min, but feel almost like falling asleep.
Elapidae – Elapids (Elapinae)
The Elapinae, or land-based elapids are the largest species complex of true venomous snakes, including cobras, mambas, taipans and coral snakes. Elpapids are very active snakes and can often be seen hunting for their prey during the day. Compared to viper, they are more defensive, but also more predictable since their active body langue tell you how the snake feels. They may not have such advanced Venom delivery mechanisms like viper, but their do not need it. Elapids will actively look for prey and sense their presence with the flickering tongue, often ending up chasing their prey. After striking, Elapids usually hold on to their victim and sometimes start swallowing while its still alive. Their fast acting, potent venom makes in impossible for the victim to defend itself.
When confronted, Elapids will try to escape, before hissing, twitch and striking to chase their threat away. Often, they will strike out many times consecutively, but without delivering any doses of venom (dry biting). This is to scare they threat and avoid wasting precious venom. Some have developed super cool defensive strategies, like the cobra, who spreads its top rips to seem larger and scare its opponent.
Elapidae – Sea snakes (Hydropiinae)
Sea snakes, Hydrophiidae, are a rather small, now individual family featuring only 11 Genera. However, all of them possess extremely potent toxins, most even more toxic than those of any land snakes. They actively hunt for fish or small aquatic mammals, which they kill almost instantly with their toxic venom. They mostly rely on their sense of water pressure, trough which they can detect slight movements around them to locate their pres. Sea snakes usually stay underwater anywhere from 1 – 3 hours, after which they will take a short breath at the surface. They have all developed a flat shaped tail, to aid them with swimming.
Colubridae – Venomous (rear-fanged) Colubrids
All colubrid snakes have a duvernoic gland, which can technically store and produce venom. However, almost all Colubrids lack a sufficient delivery mechanism, which means that most are not considered venomous.
However, some feature a primitive deliver mechanism on their rear fangs (aglyphous).
Unlike Elapids or Vipers, rear-fanged venomous Colubrids do not have needle like teeth for injection. Instead, they squeeze their venom out of their gland located directly above the rear fangs, which then runs down said rear fang and is delivered to the prey in the case of a bite.
The venom of most colubrids is considered medically not important, being either too weak or of too low quantity to do any damage to humans. Roughly 100 species however, like the boomslang or the yellow cat snake (Boiga dendrophila) include highly advanced cytotoxic and myotoxic components that target the victims intracellular tissue and muscle cell leading to and extremely painful death. Their is not much know yet about the exact components of the Venoms, which is why I cannot include further information here.
Colubrids are distributed all over the world and can be encountered in almost any habitat. When confronted, they beave much like Elapids, hissing, striking and trying to flee with incredible jerky and fast movements that make them hard and dangerous to handle.
I hope you are now a bit more knowledgeable about Venomous snakes and have learned to appreciate their huge diversity and incredible features. You have now learned to understand how venomous snakes are classified, distributed and how they differ around the world. Remember that snakes to not mean you any harm and mostly want to be left alone. Under no circumstances do they want to bite and waster their precious venom on you. Now as promised, here is a list of
The 10 most Venomous land snakes in the World
- Bungarus candidus (Malaysia)
- Oxyuranus microlepidotus (Australia)
- Pseudonaja textilis (Australia)
- Oxyuranus scutellatus (Australia)
- Bungarus multicinctus (Taiwan)
- Notechis scutatus (Australia)
- Pseudonaja mengdeni (Australia)
- Pseudechis australis (Australia)
- Austrelaps superbus (Australia)
- Acantophis antarcticus (Australia)
This list is according to the LD50 scale for mice, which means that there may be other lists that follow a different order according to a different scale. All these snakes are incredibly venomous and they potency may vary according to locations and individuals. Such a list should not be used as a reference for the most dangerous snake, since that depends mostly on temper, defensiveness, quantity of venom delivered and physiological attributes of the victim. All venomous snakes are potentially very dangerous and should never be handled by unexperienced people.
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