Poisonous spider

I have 2 friends debating over poisonous spiders. One says they are all poisonous to a point and the other says this not true. I know there is a difference between poisonous and venomous and that not all are venomous, but are they all poisonous?

IANA spider expert and welcome any correction by such but my understanding is that the term “poisonous” is often misused wrt spiders. Something is poisonous to you if you come into contact with, ingest or inhale it and it causes ill effects. While cyanide and mushrooms might be poisonous, eating spiders probably won’t hurt you provided they don’t bite you in the process.

“Venomous” is a different story entirely. Spider venom, like snake venom, is a protein that must be injected to be effective. In most cases, it’s dosed to kill other small insects and won’t kill a human. Yes, most are venomous. There are only two kinds of spiders that lack venom glands. However, only a small percentage, way less than 1%, are capable of injecting a venom that will cause significant illness or death in humans.

Perhaps relevant, I have recently again come across some conversation (maybe on the SDMB?) that suggests that a lot of points of skin irritation that people awaken with are often referred to as spider bites, but virtually none of them are. Even dermatologists are prone to making these kinds of diagnoses, apparently, but it seems as if even venomous spiders seldom bite people, and even if they do, the venom isn’t potent enough to even raise a bump. And almost none of the little itchy, pink, raised spots of irritation on the skin are caused by spiders. xo, C.

I got actual spider bites while sleeping, and to stop it I would vacuum all the joists in the basement until the webs and spiders I found were gone. This stopped the problem from occurring every few nights in my basement room. I had to do this about once a year. I don’t blame all welts on spiders, but it does happen. I really didn’t have it happen once I was out of the room for good.

I think this distinction is mentioned and understood in the OP.

“I know there is a difference between poisonous and venomous and that not all are venomous, but are they all poisonous?”

In other words, regardless of whether they are capable of envenomating a target, are they in fact oogifying to injest? (Aside from the fact that eating a spider is pretty much by definition pretty oogy.)

CC, if you can find where you read that discussion, I’d appreciate it if you would post it here. My spider bite thread from a couple of years ago never got a very satisfactory answer, and I’d like to read the discussion…

I can’t off hand find the article that I was referring to. I’ll keep searching, because someone here (a woman, perhaps, from Australia) is an arachnophile and she may have referred to this “fact” in her post. Meanwhile, I have found these three sites that seem to indicate that many bites or lesions attributed to spiders are not, in fact caused by them. http://www.marion.ohio-state.edu/spiderweb/Spider%20Bites.htm, http://saintmurse.blogspot.com/2005/06/thats-not-spider-bite.html, and http://news.bbc.co.uk/2/hi/health/3539410.stm

This is the best I can do at this point. I’ll keep looking.

That is completely inaccurate, incorrect and untrue.

A spider is posisonous if it produces poison, ie a substance capable of doing harm.
It is venomous if it is capable of producing venom, ie a biological substance capable of doing harm.

I have no idea where this particular myth came from but it has no basis in etymology or biology. When referring to biological entities venom and poison are synonyms. All venomous creatures are poisonous and vice versa.

Related thread:


I’m afraid that’s inaccurate and also untrue. And possibly incorrect.

Although the terms are sometimes, very loosely, used interchangeably, nevertheless in a meaningful discussion of biology, venom and poison are different; it’s a useful distinction. Toadstools are poisonous; a viper is venomous.

It’s a good thing spiders aren’t generally poisonous (as opposed to venomous); some of them are enjoyed as food in some parts of the world, e.g., big, hairy, meaty spiders in Cambodia, roasted directly on a fire. Eight drumsticks.

Blake, like you I used not to make a distinction, then years ago was informed that the difference was both important and recognized. Therefore, I searched through a number of reputable article before making my statement above and still believe it to be true.

Poisonous spiders - an inaccuracy.
Spiders use venom to kill their prey after they captured it in their web or by other means. A spider is only poisonous if one gets ill after eating it, so the term poisonous spiders is misleading and the correct word to use to describe these spiders is venomous.

From the California Academy of Sciences:
"Poison vs. Venom

These terms are often used interchangeably, but they actually have very different meanings. It is the delivery method that distinguishes one from the other. Poison is absorbed or ingested; a poisonous animal can only deliver toxic chemicals if another animal touches or eats it. Venom, on the other hand, is always injected. Every venomous animal has a mechanism to inject toxins directly into another animal. Stab with tails. Slash with spines. Pierce with fangs. Spike with spurs. Shoot with harpoons. Chew with teeth."

Columbia University provides this description:
“Venoms vs. Poisons
Generally, a poison is a toxic substance that is distributed throughout the tissues of an animal’s body. These animals lack any specific or localized apparatus for producing, storing or delivering poisons. Instead, the whole body, or large parts of it, is toxic. Typical poisonous animals are frogs, newts and jellyfishes.
Contrary to poisons, venoms of animals are produced, stored and delivered by a very specific set of organs, and venoms are not distributed freely in other tissues of the animal body. Typical venomous animals are the venomous snakes, scorpions and cone shells.”

As I first mentioned, if this is inaccurate then please let’s compare terminologies and get this figured out.

I wasn’t positive from the tone of the OP if in fact the distinction was understood and, thus, decided to make sure we were on the same page in our understanding.