Have you ever heard that you're only safe from the dangerous venom of daddy long leg spiders because they don't have fangs long enough or sharp enough to break through human skin? If you’ve heard this rumor, you’re not alone. It's a myth that's been around for generations, but there is no truth to it.
Breaking down this myth has to be done in a few steps. First, there's the question of what is a daddy long legs. Next, we have to talk about whether daddy long legs spiders are venomous. And if they are, how venomous they are.
On the question of what is a daddy long legs, the answer is complicated because daddy long legs is a generic term people use to describe many different long-legged creatures. Some are spiders and some are not. Among the things we call daddy long legs are crane flies, which are flies that look like large mosquitoes, and harvestmen, which are arachnids, but not spiders.
Harvestmen are spiderlike creatures, but they are not spiders for a few reasons. First, they do not have venom, which virtually all spiders have. They also don't have silk glands like spiders do, and they only have two eyes, compared with the eight eyes most spiders have. In addition, harvestmen have only one body part, while spiders have two.
Words to know
Absorb: To take in or soak up. Immobilize: To prevent something from moving as normal. Ingest: To take into the body by swallowing.
Potent: Having great power or effect. Secrete: To produce and discharge.
The spiders that people refer to as daddy long legs are pholcid spiders. These spiders belong to the Pholcidae family of spiders and are also known as cellar spiders.
There are hundreds of cellar spiders in the world, and humans are often quite familiar with them because some species are commonly found indoors, including in our houses. When they aren't taking up residence in our basements, attics and dark corners, they can be found in quiet, dark places, including caves, burrows and crevices.
Now that we've settled the matter of what exactly a daddy long legs is, we can focus on whether they are venomous and whether that venom is harmful. On the first matter, the answer is yes. The cellar spiders we call daddy long legs do produce venom. Virtually all spiders do. Of the thousands of spider species in the world, only two small families do not produce venom.
So if they are venomous, are daddy long legs a risk to humans? The answer is no. The venom from a cellar spider will not harm humans. In fact, the venom of cellar spiders and other pholcid spiders is relatively mild by spider venom standards.
So where did this myth come from? It's thought to be because cellar spiders hunt and kill dangerous spiders, such as black widows. As the myth goes, if they are able to kill such dangerous spiders, they must have even more potent venom. In truth, cellar spiders don't rely on their venom to hunt and catch black widows and other spiders. Instead, they use long strands of silk to trap and immobilize them.
While we’re on the topic of venomous spiders, let’s clear up a few more things. First, while virtually all spiders make venom, only a tiny number are dangerous to humans. Of about 50,000 known spider species in the world, only 25 have venom that capable of harming humans. That amounts to only 1/20th of 1% of all spider species in the world being dangerous to humans.
Lastly, people often say spiders like black widows and brown recluses — two of those few spider species that can harm humans — are poisonous, but they are not. Poisonous and venomous do not mean the same thing. The difference between poisonous and venomous relates to how toxins are administered. Venomous animals, like black widow spiders, inject their toxins into you, usually via a sting or bite. Poisonous animals secrete toxins, usually through their skin, and people — or other animals — get sick from ingesting or absorbing the toxins.
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