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From my layman understanding, animals that inject venom into the bloodstream by biting or poking are venomous. And ones that harm you when you eat them are poisonous.

Are there any animals (or plants) that fit both descriptions?

I'm guessing eating a venomous rattlesnake will give you an upset stomach but not cause enough damage to be classified as poisonous. And I'm pretty sure poisonous tree frogs don't bite into their prey and inject them with anything.

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9  
Any stomach upset from eating rattlesnake is likely to be purely psychosomatic. – jamesqf yesterday
    
What is poisonous depends on who (what species) is eating it, so you might want to specify if you are specifically interested in animals that are poisonous to humans. – fileunderwater yesterday
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Anecdotally, people consume the venom sac of cobras in cognac. Apparently this causes some mild hallucinations (and if you happen to have a cut where it enters your bloodstream before the venom is neutralized by your stomach acids, it kills you) – Wayne Werner yesterday
    
Eating rattlesnake is pretty common. They're not at all poisonous. – Don Branson 20 hours ago
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@WayneWerner - ...and now, across America, thousands of idiots will start raising cobras for their venom sacs...which should, predictably and in short order, raise the average intelligence of Americans. – Bob Jarvis 56 mins ago
up vote 48 down vote accepted

That is certainly an interesting question!

First, to clarify definitions:

To be considered venomous the toxic substance must be produced in specialized glands or tissue. Often these are associated with some delivery apparatus (fangs, stinger, etc.), but not necessarily.

To be poisonous, the toxins must be produced in non-specialized tissues and are only toxic after ingestion.

Interestingly, many venoms are not poisonous if ingested.[1]

I know of at least three species that produce both poison and venom. One is a snake (although not a rattlesnake, which are, in fact, edible): Rhabdophis tigrinus, which accumulates toxins in its tissues, but also delivers venom via fangs.[2] The other two are frogs: Corythomantis greeningi and Aparasphenodon brunoi, which have spines on their snout that they use to deliver the venom.[3]


[1] Meier and White (eds.). 1995. Handbook of clinical toxicology of animal venoms and poisons. Boca Raton, Fla.: CRC Press, 477p.

[2] Hutchinson et al. 2007. Dietary sequestration of defensive steroids in nuchal glands of the Asian snake Rhabdophis tigrinus. PNAS 104(7): 2265-2270.

[3] Jared et al. 2015. Venomous frogs use heads as weapons. Current Biology 25, 2166-2170.

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3  
Interesting, I got different answers when I asked for the difference between "poison" and "venom" on english.SE. – svick yesterday
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But not too surprising. Try asking the definition of significant on english.SE and Cross Validated and see how disparate the answers can be. English.SE is concerned with general parlance, whereas, biology.SE is (generally) more concerned with the technical conventions. That is a good object lesson that definitions are only definite within a field. – et is yesterday
    
Can you please add links to your sources? I don't know if the book is available on Google books or some other resource, but the two journal articles will be available via PubMed. This will very much help people who want to check your claims, as well as those who wish to learn more. If Wikipedia articles (or some other better resource) are available for the animals you mention, you should link to them as well. – MattDMo yesterday
    
@svick Most of the answers to your question cite no sources. Interestingly, those that do actually align quite nicely with this answer. – talrnu yesterday
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@MattDMo I've added links. Luckily, Meier and White (1995) is available on Google (it is also available at any library with inter-library loan service). I think you'll find the claim you are wanting to check on page 3, first sentence. – et is 16 hours ago

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