Snakes vs. Spiders: Which Creature Is Deadlier to Humans?

Few creatures fill people with as much dread and fear as spiders and snakes. In fact, many people develop an extreme, overwhelming fear of spiders (arachnophobia) or snakes (ophidiophobia), and these fears are not completely irrational. Throughout the world, you can find snakes and spiders that produce enough venom to kill a person. Some are so deadly that a single bite could kill nearly a hundred grown adults. These fearsome creatures frequently prey on animals much larger than themselves and possess killer instincts. While most rarely act aggressively toward humans, they will attack if provoked or cornered. So in a comparison of snakes and spiders, which is deadlier?

To answer this question, we’ll first need to look at snakes and spiders as a whole. Then, we’ll identify what percentage of snakes and spiders possess the ability to kill a human, and where they live. Finally, we’ll take a look at three dangerous snakes and three threatening spiders. Based on this information, we’ll determine which is deadlier to humans.

Comparing Snakes vs. Spiders

There are over 4,000 snake species worldwide and over 53,000 known spider species. However, of these thousands of species, only a small fraction poses a real danger to humans. For example, only around 600 snakes are capable of causing serious injury, while between 250–300 pose a potentially lethal risk. Although nearly all spiders are venomous, there are only around 20-25 species throughout the entire world with a bite that is medically significant to humans.

	Snakes	Spiders
Total Species	over 4,000	over 53,000
Species Capable of Killing a Person	250-300	20-25
Most Venomous Species	Inland Taipan Snake	Sydney Funnel-Web Spider
Annual Deaths (U.S.)	<6	<3
Annual Deaths (Worldwide)	81,000-138,000	Unknown

It’s worth mentioning that while venomous spiders can be found in almost every country on Earth, not every country or region is home to venomous snakes. After all, several countries do not have any native snakes including Iceland, Ireland, and New Zealand. Snakes also do not live in the northern regions of Finland, Sweden, Norway, Russia, or Canada. However, although spiders are more widespread than snakes, snakes kill far more people each year than spiders. According to the World Health Organization (WHO), between 81,000 and 138,000 people worldwide die from snake bite envenomation each year. The majority of these deaths occur in countries in Africa and Asia where antivenin is less available. In the United States, fewer than six people per year die from snake bites.

The number of deaths worldwide attributable to spiders is less well known. Many countries do not keep good records of spider bite fatalities. In the United States, fewer than 3 deaths are attributable to spiders each year thanks to the widespread availability of antivenin. Available evidence suggests that worldwide, spider bite fatalities are extremely rare, likely numbering less than a few dozen per year.

Most Dangerous Snakes and Spiders

To continue our comparison of snakes and spiders, we’ll take an in-depth look at three spiders and three snakes that pose a substantial threat to humans. This does not mean these are the deadliest snakes and spiders in the world; rather, they are examples of species that are medically significant.

Black Widow Spider

The black widow spider is one of the most feared and widely recognizable spiders in the world. It belongs to the genus Latrodectus, which includes 34 different species of varying size and venom potency. Other notable widow spiders include the brown widow, red widow, Australian redback, and South African button spider. The black widow spider produces a neurotoxin that can cause latrodectism, the symptoms of which include muscle pain and spasms, cramps, excess sweating, elevated heart rate, and even death. That said, black widow spiders aren’t known to be aggressive and are rarely responsible for fatalities.

Saw-Scaled Viper

Saw-scaled vipers are small venomous snakes in the genus Echis. They range throughout arid regions around the equator including Saudi Arabia, northern Africa, and India. Although they may not possess the most potent venom, saw scaled vipers are still regarded among the most dangerous snakes in the world. These snakes are notoriously aggressive and very quick to strike, so bites are more common from snakes in this genus than with other snakes. Case-fatality rates vary widely depending on the species or subspecies and treatment access. However, it is estimated that more people die each year from saw-scaled viper bites than from almost any other snake species.

Brazilian Wandering Spider

The Brazilian wandering spider (Phoneutria fera and P. nigriventer) holds the distinction of having the largest spider venom glands. A native to Central and South America, the Brazilian wandering spider gets its name from its habit of wandering the jungle floor at night in search of food. Its relatively aggressive nature, combined with its frequent presence in densely populated areas, makes it particularly dangerous. Its venom contains a complex neurotoxin that has systemic-wide effects. More people require hospitalization in Brazil due to its bite than any other spider.

Forest Cobra

The forest cobra (Naja melanoleuca) is among the world’s deadliest cobras due to its venom. While the Caspian cobra (Naja oxiana) possesses more potent venom, the forest cobra far outstrips it in terms of venomous load. In a single bite, a forest cobra can deliver an average of 571mg of venom and a maximum of up to 1102mg of venom. As such, a single forest cobra possesses enough neurotoxic and cytotoxic venom to kill an estimated 65 people. Envenoming by a forest cobra is so severe, it is classified by the WHO as a snake of the highest medical significance.

Sydney Funnel-Web Spider

According to many experts, the Sydney funnel-web spider (Atrax robustus) is the most venomous, and possibly the most dangerous, spider in the world. While its venom is not as potent as the Brazilian wandering spider, it delivers a larger venom load per bite. In particular, it is the male Sydney funnel-web spider that is especially dangerous. The male Sydney funnel-web spider possesses venom that contains robustoxin, a neurotoxin that attacks the nervous system. As its name implies, you can only find the Sydney funnel-web spider in and around the city of Sydney. Its closeness to such a dense population center is another reason the spider is so deadly, as it means that spider bites are more common.

Inland Taipan Snake

The inland taipan (Oxyuranus microlepidotus) is widely considered to be the most dangerous snake in the world and one of the most life-threatening creatures in general. Also known as the western taipan or fierce snake, it is only found in central east Australia. The inland taipan’s venom is so toxic that it is said to be capable of killing over 100 grown adults or 250,000 mice. Its venom contains a complicated mixture of toxins, including neurotoxins, hemotoxins, and myotoxins. Luckily, the inland taipan rarely bites people unless provoked.

Which Is Deadlier to Humans: Snakes or Spiders?

Given their small size, most spiders pose little threat to humans. The majority of spiders with potent venom rarely bite humans, and even when they do, spiders rarely deliver a large enough venom load for the bite to prove fatal. Typically, venomous spiders are only a serious threat to very young children, the elderly, or adults with compromised immune systems.

Although there are fewer snake species than spider species in the world, more species of venomous snakes pose a danger to humans. Additionally, due to their larger bodies and fangs, these venomous snakes present a substantial risk to humans, given that they can deliver a much larger venom load per bite. The majority of deaths occur in places where antivenin is scarce or unavailable, leading to poorer outcomes. So, when it comes to snakes vs. spiders, snakes are clearly much deadlier to humans.