Can Snakes Spit Venom?


There are about 3,400 species of snakes, and less than 10% are venomous. The venom of snakes is one of their most notable characteristics; however, not all snakes are poisonous to humans, although they are poisonous to their prey.

Some cobra species can accurately spit venom at their prey up to three metres away. The venom is harmless to the skin, but if it enters the eyes, then it will blind its prey. Venom is spat from their fangs which have front-facing orifices. However, cobras can also inject venom by biting their victim.

This article explains everything about snakes that spit venom and this peculiar and dangerous defence technique.

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Photo of cobra

Can snakes spit venom?

Several cobra species can spit venom from their fangs when defending against predators or catching prey.

This sprayed venom is harmless to intact skin. However, it can cause permanent blindness if it gets into the eyes and is not treated.

Many snakes have a venom gland that comes in contact with specialized teeth or fangs. These serve as a syringe-like device. Their function is to kill or paralyze their victim for consumption, allowing them to eat larger animals.

Most snakes use their venom to stun and hunt their prey as they inject the venom through their fangs and, through a direct bite, the venom is injected into a wound and quickly passes into the bloodstream.

But some types of cobra also use it as part of their defensive strategy by spitting it from a distance and blinding their predator.

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What types of snakes spit venom?

These are snakes of the genus Naja that live in Africa and Asia.

Naja ashei, Naja katiensis, Naja nubiae, Naja pallida, Naja mossambica are from Africa. From Asia they are the Naja siamensis, Naja sputatrix, Naja sumatrana, Naja miolepis, Naja philippinensis.

Molecular dating suggests that African cobras began spitting venom about 6.7 million years ago, while Asian cobras evolved this behaviour later, about 2.5 million years ago. They have independently developed the ability to spit venom.

Each species of spitting cobra has developed a different venom cocktail for this purpose, which is due to variations in their diet. Yet, they all share a common characteristic: the venom is designed to cause terrible and sudden pain to the attacker.

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How far can snakes spit venom?

Some snakes, such as the spitting cobras of the genus Naja, use it as part of their defensive strategy, spitting it from a distance of up to 2 meters (6,6 feet)  with great precision into the eyes of their potential predator.

The black-necked spitting cobra (Naja nigricollis) from Africa is a venomous snake of the asp family (Elapidae), capable of shooting venom up to three meters away in case of danger.

Some types of Viperidae even perform this defence mechanism. The Mangshan pitviper is characterized by good aim when spraying its venom.

Rinkhals (Hemachatus haemachatus), although not belonging to the cobra genus Naja, can also spit venom as their primary defence.

Unlike other cobra species, whose venom is neurotoxic, the venom of spitting cobras is cytotoxic. When injected into their prey, it can cause blindness, tissue destruction, neuromuscular paralysis, and death asphyxiation.

How did snakes learn to spit venom?

Spitting venom is a trait that evolved thanks to two crucial adaptations.

Snakes gained the ability to hold their bodies more than one meter above the ground. They also began to flatten their head bones when threatened, thus forming a threatening posture in the face of predators. This gives them an ideal posture to ensure that the venom reaches further.

The second adaptation was a modification to the opening of the venom injection channel. This made it possible to eject it from a distance of up to two and a half meters with great precision toward the eyes of the potential aggressor.

Most snakes primarily employ venom to paralyze or kill a potential meal. Venom is the sole long-distance destructive defence adoption among roughly 4,000 snake species, targeting specific sensory tissues.

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What kind of venom do cobras have?

An international research group involving the Instituto de Biomedicina de Valencia (IBV), a centre of the Spanish National Research Council (CSIC), published in the journal Science investigated this particular ability of spitting cobras.

They determined the venom composition of three lineages of cobras that independently developed their ability to spit venom.

The typical venom of most cobras is based on three-finger cytotoxic toxins (3FTx), a group of polypeptides believed to serve, among other things, to destroy tissues, which gradually causes pain.

However, the venom of spitting cobras is different; it hurts intensely and much faster. So the researchers looked for other compounds in three spitting cobras that could directly activate the pain neurons.

According to the results, the three different groups of spitting cobras increased their PLA2 toxins or phospholipase production.

These are innocuous, enzymatically active proteins that have a catastrophic impact and trigger neuronal pain when combined with three-finger toxins.

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Photo of cobra

Types of snake venom

When we talk about snake venom, we refer to highly modified saliva composed of a complex mixture of toxins, as their salivary glands produce it.

Toxins can be classified according to the organ or tissues they affect. Snake venom toxins are classified into three types:

Cytotoxins: substances toxic to cells. Most of the necrotic effect of cytotoxins occurs at the bite site.

Neurotoxins: toxic substances that affect the nervous system. They act mainly by interrupting the action of neurotransmitters at synaptic junctions.

Hemotoxins: toxic substances that affect the blood, either by their cytotoxic effect on erythrocytes or coagulation factors.

Some venoms have a mixture of both groups, so it is considered that each poison should be studied separately without assuming that one is equal to the other.

However, there are exceptions: the venom of the zebra spitting cobra Naja nigricollis is composed primarily of hemotoxins, while the venom of the Mojave rattlesnake Crotalus scutulatus is primarily neurotoxic.

Conclusion

Around the world, there are many snakes, some more dangerous than others, but there is no doubt that spitting cobras are one of those that attract a lot of attention due to their particular characteristics.

Researchers discovered that this is a defence method that different species developed in other parts of the world millions of years ago, launching a cocktail of toxic substances to escape a dangerous situation.

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