What life forms produce poisons that are totally harmless to humans

[Quercus]

Just a minor correction to the OP: The classic antibiotic is produced by the penicillum fungi (not a bacteria), though it is to fight bacteria.

I can think of one reverse example: the capsaicins produced by chili peppers, while not terribly toxic to humans are unpleasant at large doses. However, they have no effect at all on birds.

[RenaissanceMan203]

@astorian

When I was a kid, I was always told that there are only four venomous snakes in the USA: the rattler. the cottonmouth, the copperhead and the coral snake.

Today, we know that isn’t true. MANY snakes, including “harmless” ones that are sold as pets, do in fact have SOME venom. It just so happens that a garter snake doesn’t produce enough venom to people hurt most people.any real harm.

Similarly, MOST frogs and toads have SOME toxins in their skin. Poison dart frogs aren’t unique. It just so happens that most frogs don’t produce toxins potent enough to sicken people, let alone kill them.

Thanks for this post.

[Francis_Vaughan]

Another class of chemicals might be things like pyrethrum. Mammals have an enzyme that degrades it - so although a neurotoxin - it doesn’t kill us. Insects succumb. Of course some insects evolve a resistance, and not all mammals are as well protected as others.

Permethrin, a synthetic form of pyrethrum, won’t affect humans or dogs, but is well known to kill cats (at least one of the common isomers will.) Hence why you must never use flea treatments only intended for dogs on cats.

[adaher]

The sea anenome’s neurotoxin is harmless to humans, at least in the dose that it can deliver.

[FlikTheBlue]

@Quercus

Just a minor correction to the OP: The classic antibiotic is produced by the penicillum fungi (not a bacteria), though it is to fight bacteria.

I can think of one reverse example: the capsaicins produced by chili peppers, while not terribly toxic to humans are unpleasant at large doses. However, they have no effect at all on birds.

What makes this phenomenon more interesting is why peppers evolved this way. When a mammal eats a pepper, it’s digestive system will destroy the pepper seeds. A bird’s digestive system, however, does not destroy pepper seeds, and therefore birds help propagate the species while mammals don’t.

[Broomstick]

@Hari_Seldon

Theobroma (literally food of the Gods) is poisonous to dogs and cats at least, but utterly divine for this chocoholic.

Also birds.

Actually, humans have more tolerance towards theobroma than most critters.