Australia's most dangerous snakes.

What is the most dangerous Australian Snake?

The aim of this section of the website is to give some clarity as to how the terms used surrounding reptiles and their potential dangerousness. While historically the terms venom and poison were interchangeable, they are now used for different meanings.

 

To begin we need to define a few terms:
Venom –  a specialised type of toxin that can  cause a physiological injury that is injected via a bite or sting.

Poison - a toxin that can cause a physiological injury that may enter the body via swallowing or inhaling .
Toxungen – a toxin that is released from one animal and on contact the toxin can cause a physiological injury.
Venom yield- the amount of venom that is injected in a typical snake bite.
LD50-  this is the lethal dose, that kills 50% of the animals in laboratory testing. Most LD50 experiments use laboratory raised mice. Snake venom is very specific, you can NOT extrapolate the LD50 from mice to predict the effect on human beings.

 

Occasionally an animal can be both venomous and poisonous. In snakes a classic example is the Tiger Keelback Rhabdophis tigrinus. This species has a nuchal gland that stores toxins sequestered from their prey (toads) and is used as an anti-predator system.
Spitting Cobras and Rinkhals are both venomous and toxungenous. While they can still bite making them venomous, they can as also spit and when the toxin comes into contact with the eye it can cause significant injury.
Many factors can influence the toxicity of the venom of a snake- they can include the species location, the age of the snake, the health of the snake and even the injection site. The injection site for most elapids in subcutaneous due to the relatively short fangs. – Vipers and pit vipers can inject intramuscularly or subcutaneously,

 

What makes a snake dangerous?
There are generally five factors used to determine how dangerous a snake is:
The toxicity of the venom, the venom yield – amount of venom injected, the efficacy of the venom delivery system- the position and length of the fangs, the disposition of the snake and finally the likelihood at snake would come into contact with a person.
While an Inland Taipan Oxyuranus microlepidotus – is the most toxic snake in the world to mice,  has a moderate venom yield, its generally fairly even natured and in the wild almost never comes into contact with people. It close relative the Coastal Taipan Oxyuranus scutellatus is less toxic but has a much higher yield, is nervous and found in close proximity to people. Therefore they are much more dangerous to people.

 

Lastly, in Australia we have some very large constrictors, while they might not be venomous species they can still be dangerous and have been implicated in at least one death locally.
If you click on the picture of the Common Adder below there is a table that list the most toxic snakes in the world.  Below the Common Adder is some information  on Australian land snakes that are more commonly encountered, either in the wild or in captivity.

The properties of Venom

Snake venom comes from the salivary glands of venomous snakes. Venomous snakes use venom to kill prey and aid in the digestive process.

Protein is the primary component of snake venom.  Toxic proteins are what causes the harmful effects of snake venom. Snake venom also contains enzymes. These enzymes  help speed up chemical reactions that will cause a break in the chemical bonds between large molecules. These enzymes in the venom can aid in the breakdown of carbohydrates, proteins, phospholipids, and nucleotides. Toxic enzymes will also lower blood pressure, destroy red blood cells and inhibit muscle control. An additional component of snake venom is polypeptide toxin. Polypeptides are chains of amino acids, consisting of 50 or fewer amino acids. Polypeptide toxins disrupt cell functions leading to cell death. Some toxic components of snake venom are found in all poisonous snake species, while other components are found only in specific species. Although snake venoms are composed of a complex collection of toxins, enzymes, and non-toxic substances, they have historically been classified into three main types: cytotoxins, neurotoxins, and hemotoxins. Other types of snake toxins affect specific types of cells and include cardiotoxin, myotoxins, and nephrotoxins.

Cytotoxins are poisonous substances that destroy body cells. Cytotoxins lead to the death of most or all of the cells in a tissue or organ, a condition known as necrosis. Some tissue may experience liquefactive necrosis in which the tissue is partially or completely liquefied. Cytotoxins help to partially digest the prey before it is even eaten. Cytotoxins are usually specific to the type of cell they impact. Cardiotoxins are cytotoxins that damage heart cells. Myotoxins target and dissolve muscle cells. Nephrotoxins destroy kidney cells. Many venomous snake species have a combination of cytotoxins and some may also produce neurotoxins or hemotoxins. Cytotoxins destroy cells by damaging the cell membrane and inducing cell lysis. They may also cause cells to undergo programmed cell death or apoptosis. Most of the observable tissue damage caused by cytotoxins occurs at the site of the bite.

Neurotoxins are chemical substances that are poisonous to the nervous system. Neurotoxins work by disrupting chemical signals (neurotransmitters) sent between neurons. They may reduce neurotransmitter production or block neurotransmitter reception sites. Other snake neurotoxins work by blocking voltage-gated calcium channels and voltage-gated potassium channels. These channels are important for the transduction of signals along neurons. Neurotoxins cause muscle paralysis which may also result in respiratory difficulty and death. Snakes of the family Elapidae typically produce neurotoxic venom. These snakes have small, erect fangs and include cobras, mambas, sea snakes, death adders, and coral snakes

Examples of snake neurotoxins include:

  • Calciseptine: This neurotoxin disrupts nerve impulse transduction by blocking voltage-gated calcium channels. Black Mambas use this type of venom.

  • Cobrotoxin, produced by cobras, blocks nicotinic acetylcholine receptors resulting in paralysis. 

  • Calcicludine: Like calciseptin, this neurotoxin blocks voltage-gated calcium channels disrupting nerve signals. It is found in the Eastern Green Mamba.

  • Fasciculin-I, also found in the Eastern Green Mamba, inhibits acetylcholinesterase function resulting in uncontrollable muscle movement, convulsions, and breathing paralysis.

  • Calliotoxin, produced by Blue Coral Snakes, targets sodium channels and prevents them from closing, resulting in paralysis of the entire body. 

Hemotoxins are blood poisons that have cytotoxic effects and also disrupt normal blood coagulation processes. These substances work by causing red blood cells to burst open, by interfering with blood clotting factors, and by causing tissue death and organ damage. Destruction of red blood cells and the inability of blood to clot cause serious internal bleeding. The accumulation of dead red blood cells can also disrupt proper kidney function. While some hemotoxins inhibit blood clotting, others cause platelets and other blood cells to clump together. The resulting clots block blood circulation through blood vessels and can lead to heart failure. Snakes of the family Viperidae, including vipers and pit vipers, produce hemotoxins.

Neurotoxins - toxins that are destructive to nerve tissue. Neurotoxins are an extensive class of exogenous chemical neurological insults that can adversely affect function in both developing and mature nervous tissue.  The term can also be used to classify endogenous compounds, which, when abnormally contacted, can prove neurologically toxic. Though neurotoxins are often neurologically destructive, their ability to specifically target neural components is important in the study of nervous systems.  Neurotoxins inhibit neuron control over ion concentrations across the cell membrane, or communication between neurons across a synapse. Local pathology of neurotoxin exposure often includes neuron excitotoxicity or apoptosis but can also include glial cell damage. Macroscopic manifestations of neurotoxin exposure can include widespread central nervous system damage such as intellectual disability, persistent memory impairments, epilepsy, and dementia Additionally, neurotoxin-mediated peripheral nervous system damage such as neuropathy or myopathy is common. Support has been shown for a number of treatments aimed at attenuating neurotoxin-mediated injury, such as antioxidant and antitoxin administration.
Pre- & Post-synaptic neurotoxins - Presynaptic and postsynaptic neurotoxins are two groups of neurotoxins.  Neurotoxins can be divided into presynaptic and postsynaptic neurotoxins based on their mechanism of action1. Presynaptic neurotoxins are commonly called β-neurotoxins. These neurotoxins act on the plasmatic membranes of nerve endings, promote the generation of interterminal signals, and lead to a massive stimulation of the release of the neuromediator2,3,4. Presynaptic neurotoxins are rich sources of phospholipases5,6,7,8,9 and produce neuromuscular blockade by inhibiting the release of acetylcholine from the presynaptic membrane10. Postsynaptic neurotoxins are commonly called α-neurotoxins11,12,13, and most of these neurotoxins are from the venoms of snakes of families. Postsynaptic neurotoxins bind specially to the nicotinic acetylcholine receptor resulting in the prevention of nerve transmission, leading to death from asphyxiation

Myotoxins - Myotoxins are small, basic peptides found in snake venoms and lizard venoms (e.g. mexican beaded lizard).This involves a non-enzymatic mechanism that leads to severe muscle necrosis. These peptides act very quickly, causing instantaneous paralysis to prevent prey from escaping and eventually death due to diaphragmatic paralysis.

The first myotoxin to be identified and isolated was crotamine, from the venom of Crotalus durissus terrificus, a tropical South American rattlesnake, by

Procoagulants
                Prothrombin convertors

                Anticoagulants
              Haemorrhagins
              Nephrotoxins
Cardiotoxins
Necrotoxins - a substance produced by some bacteria of the genus Staphylococcus which destroys tissue cells

For a list of the most venomous snakes (both land and water) from around the globe click on the picture of the Common Adder.  This Australian snakes on this list are in red.  How this list is complied is by the amount of venom (mg) injected (subcutaneously) per kilo of  lab mice.

Coastal Taipan

Oxyuranus scutellatus

The Coastal Taipan's natural habitat is along the coastal regions of eastern and northern Australia and the island of New Guinea. The  Coastal Taipan is the third most venomous land snake in the world.  Here in Australia, the Coastal Taipan has the longest fangs (approx 12mm). Taipans are able to strike rapidly and repeatedly, with each bite containing venom. They deliver large quantities of venom in comparison to other Australian snakes.The venom of the coastal taipan is known as the taicatoxin, which is a powerful neurotoxin. The Coastal Taipan's venom is able  kill a healthy adult human within 30mins - 2.5hrs after a lethal bite if left untreated.  Without medical treatment the mortality rate from a coastal taipan bite is nearly 100%. The venom quickly spreads in the nervous system and also the blood. Side effects can be headaches,nausea and vomiting, convulsions, paralysis, internal bleeding and severe muscle and kidney damage.  

Coastal Taipans can reach approximately three meters in length and weigh in at 6.6kg. A large and extremely intelligent snake, it can lash out when surprised,cornered or feeling threatened and injects a decent amount venom deep into the flesh in as little as two or three bites, however, these snakes tend to avoid confrontation and will escape whenever possible. Whilst the Coastal Taipan may be more venomous than the Eastern Brown, A LOT more people will come into contact with an Eastern Brown, some quite regularly depending on where they live. 

Also known as the Eastern Taipan, Giant Brown Snake

Eastern Brown

Pseudonaja textilis

Also known as Common Brown, Brown Snake

The Eastern Brown can be found across most of eastern mainland Austrlia.  Isolated populations occur in the West MacDonnell Ranges, Northern Territory and near Gordon Downs, Western Australia.  The Eastern Brown can also be found in Papua New Guinea. The  Eastern Brown is the .... most venomous land snake in the world.  Here in Australia, the Eastern Brown has the ninth longest fangs (approx 4mm). Eastern Brown's are able to strike ................... containing venom. They don't deliver large quantities of venom in comparison to other Australian snakes. The venom of the Eastern Brown is a complex venom containing neurotoxins and postsynaptic neurotoxins. The Coastal Taipan's venom is able  kill a healthy adult human within 30mins - 2.5hrs after a lethal bite if left untreated.  Without medical treatment the mortality rate from a coastal taipan bite is nearly 100%. The venom quickly spreads in the nervous system and also the blood. Side effects can be headaches,nausea and vomiting, convulsions, paralysis, internal bleeding and severe muscle and kidney damage.  

Coastal Taipans can reach approximately three meters in length and weigh in at 6.6kg. A large and extremely intelligent snake, it can lash out when surprised,cornered or feeling threatened and injects a decent amount venom deep into the flesh in as little as two or three bites, however, these snakes tend to avoid confrontation and will escape whenever possible. Whilst the Coastal Taipan may be more venomous than the Eastern Brown, A LOT more people will come into contact with an Eastern Brown, some quite regularly depending on where they live. 

Inland Taipan

Oxyuranus microlepidotus

Also known as Fierce Snake, Small Scaled Snake

Tiger Snake

Notechis scutatus

Also known as Mainland Tiger Snake, Common Tiger Snake

Mulga Snake

Pseudechis australis

Also known as King Brown

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