Certain species of snakes use their long, sharp fangs to inject their prey with venom. This venom is used to immobilize and digest prey. Not all venomous snakes have enough potency to harm humans, but some are lethal.
Snake venom is a modified kind of saliva. This venom is produced in the snake’s salivary glands, stored in sacs inside of these glands, and then sent to the fangs through ducts in the snake’s face. Different kinds of snake venom create different harmful effects. These effects include destroying body cells, interrupting nervous system function to cause paralysis, and preventing blood from coagulating to cause internal bleeding. Types of venom production vary by species, depending on what kind of prey the snake has to contend with in its territory.
Let’s learn more about how snakes produce their venom, and about the different kinds of venom that different species of snakes use.
Table of Contents:
- 1 What Is Snake Venom?
- 2 Types of Snake Venom
What Is Snake Venom?
Humans have saliva which contains enzymes that help us digest our food as we chew it. Snake venom is effectively a modified version of saliva. This saliva contains zootoxins which help the snake not only immobilize its prey but also digest its meals. Snake venom is a venomous snake’s primary defense tool against external threats.
Researchers at Tezpur University report that snake venom consists of a mixture of polypeptides and bioactive proteins. These molecules come together into complexes. The complexes have shapes that allow them to lock onto specific proteins in the victim’s cells. Depending on what kinds of proteins and polypeptides are interacting, the venom has a different result.
Snakes usually inject their venom by first biting the victim with their fangs, and then holding on while they pump in the venom. Fangs are sharp, grooved teeth that are hollow on the inside, like a syringe. Some species of snake spit the venom at their prey, such as the spitting cobra.
How is Venom Produced by Snakes?
Most vertebrates have parotid salivary glands. Venomous snakes have similar glands that produce zootoxins, and are known as modified forms of these glands. These glands are located on both sides of the head, behind and below their eyes. The glands are encapsulated in a muscular sheath.
Inside of these glands are large alveoli, which is an air sac similar to the ones found in the lungs. These alveoli are larger than they are in non-venomous salivary glands. The venom is usually stored here, rather than in the fangs. When the snake needs the venom, the venom is transported to the base of the fangs via ducts in the snake’s face. Then, the venom is injected through the fangs and into the victim’s body.
Types of Snake Venom
20 different compounds can be found in snake venom. These include proteins and polypeptides, and also mixtures of enzymes. Therefore, snake venom works on a metabolic level.
Depending on what’s present, the snake’s venom can have a different impact on its prey. Each has specified effects. All of these effects serve the purpose of immobilizing or outright killing a snake’s prey.
What Are Different Venom Effects?
There are 3 types of venom, each with a different effect on the victim’s body. Some snake venoms even contain more than one of these 3 types, creating a combination of effects.
Cytotoxins destroy body cells. This destruction results in a condition known as necrosis. Cytotoxins help the snake begin to digest its prey before it even puts the prey completely into its mouth. This is the kind of venom that results in tissue damage around a bite which is visible to the naked eye. The venom damages the membrane of your cells, causing the cells to die.
Different kinds of cytotoxins affect different cells. For example, cardiotoxins damage heart cells, myotoxins harm muscle cells, and nephrotoxins attack kidney cells. Most cytotoxic snake venoms include a combination of these types. Cytotoxins are also commonly combined with neurotoxins and hemotoxins in a single snake’s venom.
Neurotoxins are snake venoms which target the victim’s nervous system. These chemicals disrupt the chemical signals which your neurons send to each other. Neurons are an essential part of being able to move your muscles. As a result, neurotoxins cause muscular paralysis.
This paralysis not only makes it difficult for a snake’s prey to run away, but it also can cause the prey to have difficulty breathing. Some neurotoxins are strong enough to outright kill a rodent. Snakes with neurotoxin venom include mambas, cobras, death adders, coral snakes, and sea snakes.
Hemotoxins affect the victim’s blood. In a healthy body, blood coagulates. This means that when you get a cut, the blood clots itself, preventing you from bleeding to death when you get a tiny cut. People with a condition known as hemophilia have blood that does not clot like it should, making any cut a dangerous wound.
Snake venom that contains hemotoxins disrupt the blood’s ability to coagulate. It achieves this by destroying red blood cells, damaging tissues, and organs, and by interfering with factors in blood clotting. An animal that loses its ability for blood to clot can lead to serious cases of internal bleeding. They can also leave behind a trail of external blood for a snake to follow.
Other types of hemotoxins create extra clots, rather than inhibit them. These clots can stop up blood vessels, giving the victim cases of heart failure. Extra dead red blood cells in the bloodstream can also inhibit kidney function. All of these effects can lead to a quick death for the snake’s prey. Hemotoxins are commonly produced by vipers and pit vipers.
Where Did Venom Genes Come From?
Venom genes are closely related to other genes in snakes which carry out different, harmless jobs. These related genes are found in both venomous and non-venomous snakes. For example, some of these genes produce immune system proteins, which attack foreign bacteria which might invade a snake’s body. Other venom genes are very similar to those which produce digestive enzymes in the snake’s stomach.
It is possible that as snakes evolved, these genes were duplicated. Duplication leads to twice as much of a protein being generated in the snake’s body. However, duplication is a kind of mutation, and it’s possible that the mutation went further until these two initially identical genes and the proteins they made had very different purposes. Some helped the snake stay healthy, while others became tools to disable external threats and immobilize prey.
What Affects Snake Venom Production?
Snakes produce different kinds of venom. Let’s explore some of the reasons why these differences in venom production exist between snakes.
Venom Production by Snake Species
According to Nature, venom composition varies among snake species on a geographical basis. If you put different kinds of venomous snakes on a map, you will see different kinds of venom spread across the world.
This is likely because of what kinds of prey are available to these snakes in different areas. For example, in areas with larger prey animals, snakes with venom capable of taking down these larger prey animals were more likely to survive and reproduce. In other areas, snakes with weaker venoms could and do survive. Snakes that tackle larger prey, such as rattlesnakes, also are by necessity more adept at quickly producing and injecting a lot of venom than other species of venomous snakes.
Does Venom Production As Snakes Age?
Most research on snake venom to this point has been about comparing different species of snakes to each other. Less research has been conducted on how venom production in individual snakes may change over time. Of course, there are still pervasive rumors among local communities about snake venom changing over time. For example, it has been commonly said that baby brown snakes, a species found in Australia, are more dangerous than adults of the same species.
It has since been discovered that there is, in fact, a change in the brown snake’s venom as it ages. However, this change is not a decrease in danger. Bryan Fry, an associate professor at the University of Queensland, discovered that young brown snakes have venom which targets the nervous system of its prey – a neurotoxin. Adult brown snakes, on the other hand, have venom which attacks the prey’s circulatory system – a hemotoxin.
This change helps the snake switch diets as it ages. Young brown snakes usually feed on smaller reptiles, which are easily brought down by an attack on the nervous system from a neurotoxin. Adult brown snakes, on the other hand, eat mammals such as rodents. Mammals are often more susceptible to the anti-coagulation effects of a hemotoxin.
The research team also discovered that adult brown snakes have a much higher rate of envenomation than the younger snakes. The prey of an adult brown snake is immobilized much more quickly than the prey of a young brown snake. So, while the rumor had a touch of truth to it, it ultimately had the story backwards. Adult brown snakes have the more potent venom.
Do Snakes Run Out Of Venom?
Snakes only have so much venom stored in their body at a time. After a certain number of bites and injections in a short period of time, it can and will run out of venom. If a snake runs out of venom, it will take time for it to recover and produce more venom again. The amount of time varies across snake species. This production process can take days or weeks, and likely takes a lot of energy on the part of the snake.
Even without their venom, snakes can still bite and cause serious harm to their opponents. If you come across a venomous snake in the wild, even if you suspect a snake is out of venom, you still should leave it alone. If you are bitten by a snake, whether you know that it is venomous or not, you should still go to a doctor for inspection. Be able to describe the snake’s color, pattern, and any other distinctive features.
A snake will not run out of venom so quickly if it simply does not use the venom. Not all venomous snake bites include venom. According to the University of Southern California School of Medicine, around 20% of bites from venomous snakes do not actually result in any envenomation. This means that while the snake may bite its prey, the bite is superficial and does not include the snake injecting any venom.
Sometimes this is because the snake ejected the venom onto the victim’s skin instead of into the bite itself. However, often this is because the snake simply did not choose to inject any venom. Snakes know how to pace themselves and save their venom for a greater threat.
Understanding snake venom helps us appreciate the strength, diversity, and versatility of these amazing reptiles. Additionally, all the research done to understand how snake venoms work helps medical science progress. Snake venom plays an essential part not only in developing antivenoms to heal snake bites, but also in developing medicines to treat nervous system disorders and hemophilia.