Spider Facts

"Wherever you sit as you read these lines, a spider is probably no more than a few yards away."
Norm Platnick

This quote has been sending shivers up the spines of many arachnophobes since published in 1995. Realistically, there are many situations where this is an overstatement, such as astronauts reading this on the International Space Station, explorers in Antarctica, sailors in the middle of ocean, or shoppers in a gigantic mall parking lot (the last two may be more likely to be correct than you may think). However, as we study spiders more and more, we are discovering just how abundant and diverse they are, and just how accurate this statement is.

Facts About Spiders

Spiders are found on every continent across our planet with the exception of Antarctica. There are roughly 50,000 species of spiders described. However, a recent study states that we have only described about 20% of arachnid species existing today. This suggests that number could climb to around 250,000 species, and that is just the number of different kinds of spiders on Earth. The actual number of spiders we share space with is much larger and near impossible to guess, but here are some numbers.

A study of homes in North Carolina found spiders in 100 percent of them, yes all of them. Across all of the different habitats on the earth, the average density of spiders was a shocking 131 per square meter, with that density reaching over 1000 per square meter in favorable environments. Overall, if you add up all the spiders on our planet, they would weigh around 29 million tons! These estimates are exciting for arachnologists as there is so much more to learn, but they could also cause nightmares for the spider wary.

Fear of Spiders

Nervousness, cold sweats, and outright fright are fairly common reactions to spiders, in fact arachnophobia is the considered one of the most common fears of an object we have. Estimates suggest roughly 50% of women and 20% of men suffer from some degree of arachnophobia. Surprising enough, this included me before I began working on spiders, which is one of the reasons my passion lies in educating people about spiders.

Psychologists have suggested that part of our arachnophobia may be attributed to our human ancestors that lived in and around very dangerous spiders, where avoidance and fright of spiders helped them survive. This relic phobia may have been passed on today to generations that generally don’t live with dangerous spiders and thus is pointless. While nearly all spiders are venomous, very few, including the recluse spiders (4 of 11 species in U.S. considered to have dangerous bites), hobo spider (1 species in U.S. consider to have dangerous bite), and widow spiders (5 of 5 species in U.S. considered to have dangerous bites), are considered dangerous or medically important to humans. This means only about .3% of spider species in the United States have a dangerous bite. The vast majority of spiders you encounter on a daily basis are not only harmless but in fact could be considered your friend based on their role in the ecosystem.

What Do Spiders Eat?

Spiders are predators, meaning they consume other live animals. Spiders are very good predators, in fact, they are the top-level and dominant invertebrate predator of most if not all terrestrial ecosystems. A spider’s diet includes any invertebrates and vertebrates smaller (and often times much larger) than they are that they can catch. This wide range of prey includes animals that we consider pests in some way or another, including disease vectors (mosquitoes, flies, roaches) and crop pests (caterpillars, beetles, grasshoppers, aphids and more).

Spiders don’t just eat a few of these pests, they eat a massive amount. Some estimates have suggested some spiders capture as many as 3000 insects per year, and when you add this up across all the spiders on the planet, the total biomass of spider prey is somewhere between 400-700 million tons. For a reference point, the total biomass of the human population on Earth today is roughly 350 million tons. Wow!

This brings a whole new meaning to the common phrase, “The enemy of my enemy is my friend.” So with that in mind, you can breathe easy that you are constantly surrounded with hundreds, thousands, or maybe even millions of your closest eight-legged friends looking out for you all day and night.

Spider Facts for Kids

This is the information that children need to help break the cycle of a phobia that I feel is passed from one generation to the next by behavior. I want so badly to teach our next generation to respect and understand our spider friends that I wrote an illustrated children’s book about them to allow kids to identify with a spider as a heroine, not a villain.

Savanna Spider, Super Scientist, Goes to School is an engaging story about a little spider scientist that has a rocky start to her first day of Arthur O. Pod Elementary School. Throughout the book, “Science Behind the Story” popups explain the real science by the story.

Kids will have so much fun reading the story, they won’t even realize they are learning science at the same time. You can purchase this book in either paperback or Kindle eBook. The best part? A portion of the proceeds from the sales of this book are donated to the Kansas Department of Wildlife, Parks, and Tourism Chickadee Checkoff grant which supports the conservation of nongame wildlife!

Learn More About Spiders

What questions do you have about spiders? Leave them below and we’ll answer them for you!