Are All Spiders Venomous?

Most spiders are venomous, but this isn’t reason for concern. In North America, only black widow, and brown recluse spiders inflict life-threatening injuries.

Aug 24, 2023By Colt Dodd
are all spiders venomous

According to the Archives of Academic Emergency Medicine, most spiders are venomous. However, venomous doesn’t necessarily mean dangerous. There are only two deadly spiders in North America: the brown recluse spider and the black widow spider. While thousands of other species are venomous, a spider bite doesn’t always warrant a trip to the hospital.

While many people are frightened of these insects, they’re generally harmless.

Most Spiders Are Venomous But Not Dangerous

spider in a web green background
Image Credit: Wikimedia Commons

National Geographic reports that most spiders are carnivores, meaning they rely on a steady diet of other bugs to survive. However, they can’t swallow their prey whole. Rather, they inject their prey with venom to paralyze it. Then, they suck out the liquefied remains.

Here’s a fun fact: venomous and poisonous are not interchangeable terms. The National Park Service (NPS) notes that a venomous animal will inject its prey with poison. For instance, snakes, spiders, and jellyfish are venomous. Poisonous animals are deadly if eaten. Cane toads are poisonous, but because they don’t inject predators with toxins, they’re not venomous.

Only Two Spiders in North America Can Cause Fatalities

small jumping spider on man_s finger
Image Credit: Wikimedia Commons

What separates the black widow and brown recluse spider from the thousands of other non-threatening venomous spiders? Here’s what to know:

  • Brown recluse spiders have an active chemical in their venom that breaks down blood vessels and causes tissue death. Most of the time, a bite isn’t dangerous because the spider only injects a small quantity of poison into the bloodstream. Yet, the complications from tissue death can prove life-threatening.
  • According to Smithsonian Magazine, a black widow spider’s venom is 15 times more powerful than a rattlesnake’s bite. The toxins overwhelm the body’s nerve cells and cause serious inflammation. However, just like the brown recluse spider, the poison is in such a small amount, that it usually doesn’t result in serious injuries.

It's important to note that, if one’s bitten by a spider, they should consider getting medical attention. According to the Centers for Disease Control and Prevention (CDC), if the bite site is inflamed, painful, or feels hot, a doctor’s opinion is needed. If the bite isn’t an emergency, a doctor can explain how to prevent infections and other complications.

What Are the Most Dangerous Spiders in the World?

house spider against blue background
Image Credit: Wikimedia Commons

Although many people fear spiders, most people will never come face-to-face with the world’s deadliest insects. However, it’s good to know which ones really pack a punch (or, in this case, bite). Some of the world’s most dangerous spiders include:

  • The funnel web spider. Just one strategically placed bite could spell death for an unfortunate victim. Venom from a bite contains more than 40 proteins that can overwhelm the body’s nervous system. Good news: there hasn’t been a funnel spider-related death in more than 30 years.
  • The redback spider. The redback spider looks almost identical to the black widow spider, except it’s located in Australia, not North America. While deaths are rare, one-third of bite victims will suffer adverse symptoms, such as nausea, stomach pain, hypertension, and chest pain.
  • Brazilian wandering spider. The Guinness World Book of Records deems this the world’s deadliest spider. Yet, thanks to advancements in technology, deaths are rare.

Spiders are generally not ambush predators. This means they don’t pop out of nowhere and bite unsuspecting passersby. They generally only bite humans when frightened or trying to defend themselves. So, when confronted with a daddy long legs, there’s no need to burn the house down. It’s harmless.

Steps After a Spider Bite

black widow spider in a web
Image Credit: Wikimedia Commons

The CDC notes that seniors, small children, and immunocompromised people are the most likely to suffer life-threatening injuries if bitten by a spider. However, that doesn’t mean one should shrug off an insect bite. Mayo Clinic reports that, if the bite isn’t serious, one should:

  • Clean the area with soap and water
  • Apply triple antibiotic
  • Apply a cold compress to reduce swelling
  • Elevate the affected area, if possible
  • Take an over-the-counter allergy medication

What Symptoms Point to a Serious Bite?

Imagine this scenario. Someone’s rummaging through the attic looking for holiday decorations. They stick their hand into a box, and then feel a sharp, shooting pain. There’s no mistaking it; it’s a spider bite. But is the spider dangerous? What symptoms should one look out for?

One should seek immediate medical attention if:

  • They have a pre-existing health condition that could worsen in conjunction with the spider bite.
  • The bite wound itself spreads.
  • One experiences serious stomach pain.
  • One has problems breathing or swallowing.
  • The area around the bite gets redder with time.

Many people resort to the wait-and-see approach when it comes to spider bites. Yet, one should know the symptoms of a serious condition rather than risk their health.

Never Fear; Spiders Are Nature’s Helpers

spider on a red flower
Image Credit: Wikimedia Commons

When people imagine spiders, they imagine them in haunted houses, attics, and other confined spaces. However, most spiders live outside, where they eat pesky insects, including mosquitos, beetles, and wasps. This can:

  • Stop insects from overeating in a garden
  • Prevent in-home infestations
  • Reduce the spread of diseases (for instance, those transmitted by ticks)

What’s more, some spiders pollinate flowers, helping the average neighborhood garden blossom into an urban Garden of Eden. Long story short: spiders aren’t to be feared. However, if one’s concerned about whether a spider bite could prove deadly, they should visit a doctor. Alternatively, they can call the poison control center in their area.

Colt Dodd
By Colt Dodd

Colt Dodd is a sighthound enthusiast with three years of freelance writing experience. He has an Italian greyhound/Shetland sheepdog mix named Homer. In his spare time, he enjoys going to dog parks and writing fiction.