Disclaimer- I’m a herpetologist but I don’t work in venom researchers so my opinions are more informed by my area of expertise (which includes systematics).
I think this topic is obfuscated by a few confounding factors:
Toxicofera is in part taxonomic hypothesis (which is well-supported in the data)
Toxicofera is an ancestral state hypothesis
“Venomous” as a character state is a little wishy-washy and generally poorly-defined.
Point 1) is, as I mentioned, pretty well-received at the moment. As a herpetologist, I’m fairly well convinced. Point 2) however depends on how you define point 3) and I am generally dissatisfied with that.
Venoms are hugely variable throughout the tree of life, and the Toxicofera hypothesis seems to confound what counts as “venom” even more unless we are specifically testing toxicity on relevant prey items. I suspect the ancestral state for Toxicofera is more likely diverse salivary enzymes rather than something we’d recognize popularly as a “venom” as others in this thread have suggested.
I agree. If the bite of an animal transmits some substance that assists that animal in defense (by causing the predator to quickly withdraw) or subduing prey (by killing, causing paralysis, etc.), I think it can be properly called venomous. There’s evidence that the bites of some gartersnakes can cause a delayed inflammatory reaction in some humans, but is that evidence that they’re venomous? It gets a little nebulous how we define the term.
Many cats are carriers of Bartonella henselae, the bacteria responsible for ‘Cat Scratch Disease’. I’d think that the rapid inflammation may be the body’s reaction to that.
Also, cat claws in particular are often very dirty, so there are all sorts of things living in them. Cat claws evolved to be self sharpening by sloughing off the outer layers, this means that there is a lot of surface area for bacteria and other things to live in cat claws. Any of this can easily get into their mouths as well since they’re using their mouths to clean their bodies.
In this picture you can see all the little grooves, lines, and areas for bacteria between the flakes or keratin.
Why? Venom should be something an animal secrets, if not by glands, but by other tissues, if it’s from something else it doesn’t really fit. If I will transmit you my teeth bacteria with every bite and they will cause inflammation there, I’m not venomous.
The gartersnake example I mention was published as a report of possible venom in that species. Which was the point I meant to make – the definition gets a little fuzzy.
The conversation around some “venomous” insects (usually caterpillars) also gets fuzzy (ahem) like this. The argument I’ve seen is that if a traditionally canonical venom works by being an injectable compound that has evolved to cause chemical reactions like protein lysis or neurotoxicity in a different organism, why not include compounds that have evolved to trigger antihistamine overreactions (i.e., itching) when they stick you? I get the argument, but I still feel like there’s a practical difference between a puss caterpillar and a viper.
Indeed. I haven’t thought much about this, but it’s also interesting that venom is used in different ways depending on the animal. In bees, it’s purely defensive. In snakes (vipers, for example) it’s primarily to subdue prey but has the secondary purpose of defense … unless the defensive envenomation could be considered a “side effect” of biting, which many non-venomous snakes also do defensively. Not all viper bites deliver venom, so there seems to be some control of that behavior in individuals. Which might suggest that that rattlesnake that bit you might not have really intended to envenomate you since the bite itself was intended to be the deterrence.
Assigning a “cause” for an adaptation is notoriously tricky- feathers didn’t originally evolve “for” flight, giraffe necks are more likely “for” male-male competition than grazing stratum, etc. The “causes” of adaptation are often multiple and they usually change through time. I’m kind of arguing that snake venoms likely evolved as digestive aids and then diversified.
Your gartersnake example is one I go back to a lot too- I wouldn’t call gartersnakes venomous (unless their secretions have specific activity in subduing common prey- that’s not something I’m certain about) and I’d look at someone askance if I encountered them doing so. Human saliva contains some amount of enzymes which help break down food- is that venom? (I’d argue definitely not.) So this implies that there’s a point somewhere. I keep coming back to your statement- a defensive aid (it would have to have a rapid debilitating effect in my mind) or predation/digestive aid (so it would have to help subdue common prey species faster than without).
I don’t think we disagree. I was mainly pointing out that “venomous” is seemingly rather poorly defined or sloppily used in some of the literature. I wouldn’t consider gartersnakes venomous either based on current evidence. And I certainly agree that the origins of venom in species that can clearly be categorized as venomous might have been something else (such as a digestive aid).
What I still wonder about is, although rattlesnakes are clearly venomous, is the delivery of venom in a defensive bite the “intent” of the snake? That is, does envenomation of a predator act as a deterrent compared to a dry bite, since the effect on the predator might not be immediate? I think with some predators it certainly could be, based on their experience if previously bitten.
my case of sepsis took just minutes to become life threatening and get the hospital staff into a panic.
all vets have seen it before. vets and vet techs have all been bitten by cats many times. most have left work at some point to go to urgent care for all kinds of bites. some cat bites don’t blow up that way, but enough of them do that it’s a major risk factor when there’s a cat bite and there’s no way to predict which ones won’t.
and yeah, for a reaction in seconds, I’d say there’s a decent chance that an allergic reaction is also involved.
Maybe, but I get “love bites” that break the skin from time to time and they do not react, it’s just a puncture wound, not unlike a bad thorn puncture.
That’s sort of why I hypothesize that great stress and arousal includes something “extra” in the saliva, from a chemical flood the animal experiences when so aroused - hormones, enzymes - that is not usually there. Since it hurt so bad, it could be characterized as venom (okay, maybe I do not understand the nature of venom).
Yikes! That sounds so scary! I’m glad they managed to get it stopped before… well, before all that terrible stuff. .
In my case, the redline took almost a day to appear, then it moved fast! I was on my way to work and watched it progressing up my arm; so I detoured and drove straight to a medical facility. They got busy right away.
there’s nothing special here. what’s going on is depth of the wound. get it deep enough and the bacteria gets injected deeply into the skin. boom. raging infection.
what you’re describing as minor wounds that don’t react tells me that you’re not getting nearly the depth of puncture.
also worth considering is hygiene of the cat’s mouth. cats are notorious for nasty mouths. it’s not common for a cat to willingly tolerate tooth brushing, and many cats are genetically prone to resorptive lesions in their mouths that cause very serious decay. a dirty mouth is going to contribute a lot to the bacterial load delivered by any sort of bite.
there’s nothing special about what’s in the saliva in a stressed cat vs. an unstressed one. except that maybe the stressed cat might make more saliva.
and fwiw, the same applies to dog bites. big difference with dog bites is that their teeth aren’t as sharp, and don’t give quite the hypodermic needle effect. severe dog bites do have a tendency to cause tearing and cause other kinds of trauma, however. veterinary staff reporting to urgent care for an animal bite of any kind are going to get some antibiotics no matter what bit them.
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