Ask Professor Willowcox: Are Poison-type Pokémon Really “Poisonous”?

By Christie Wilcox | July 15, 2016 5:20 pm

I was born in 1985, which is a bit of an awkward year, culturally. I’m technically a millennial, but I was a bit too old for most of the fads that swept through the millennial generation. I never owned a Bratz doll. I missed the brief yo-yo boom. And I never played Pokémon, in game or card form. That’s not to say I was too cool for that sort of thing as a kid; I was a total geek. Heck, I had a dragon deck before the Onslaught block made tribal decks cool (that would be Magic the Gathering, for those who have no idea what I’m talking about)—I just wasn’t quite the right age at the right time to be hit by the Pokémon craze. I had never tried to catch a Pokémon until last week, when my boyfriend and roommate convinced me to try Pokémon Go. It’s… addicting.

A few days later, I was already one of “those” people, glued to my phone as I paced up and down Kohou street. THERE! I stopped abruptly as I engaged a Tentacool that appeared on my screen. My eyes narrowed as I gently flicked my Pokéball at the cp179 Tentacool perched awkwardly on the hood of a parked car. After a few rattles, the red and white ball became still, emitting the “Gotcha!” stars, and I did a slightly embarrassing victory dance (my friend once dubbed it my “T. rex dance” because of my jilted arm movements). As a box jelly scientist, I had been keeping a keen eye out for these jellyfish Pokémon for days, but I had only seen them off in the distance, some three footsteps away. Frustrated, I finally had decided to go hunting near a local canal on my way back home from running errands, hoping I would find these water Pokémon near, you know, water—a tactic that paid off. My goofy grin quickly changed, however, when I was awarded a metal for catching my 10th “Poison-type” Pokémon. “Poison!” I actually exclaimed aloud. “Jellies are venomous!

Poison, Niantic? Not tenta-cool.

Poison, Nintendo? Not tenta-cool.

While the terms toxin, poison, and venom are often used as synonyms, they have different meanings. Toxins are the broad category—anything that causes physiological harm in “biologically relevant” (usually small) doses is a toxin*. Toxins which are ingested, inhaled, or absorbed are considered poisons. Only toxins that are actively introduced through some kind of wound are considered venoms. As you might expect, animals that use poisons are called poisonous, and those that use venoms are called venomous. And if you follow the naming standards set forth by David Nelsen and his colleagues, then there is one more category: the toxungenous animals, which use toxins in an active manner—they don’t wait to be bitten or touched—but do not cause injury to deliver them. This distinction matters, the authors argue, because actively using toxins has evolutionary implications. Animals can fall into more than one category; spitting cobras, for example, are venomous when they bite, but toxungenous when they spit. But often, the different categories lead to different types of toxins that don’t work through other routes. Many venoms are harmless if swallowed, for example.

The formal definitions of each, according to Nelsen et al. 2014

The formal definitions of each, according to Nelsen et al. 2014

The entire phylum Cnidaria—more than ten thousand species including jellies, corals, and anemones—are venomous. They are armed with ballistic stinging cells characteristic to the group, which fire a hollow, spine-laden tubules into their victims to deliver some of the most potent venoms in the world. You have to respect their deadly toxicity: box jellies kill more people every year than sharks. And they’re formidable predators: box jellies have four eyes, complete with retinas, and are powerful swimmers capable of seeing and then chasing their prey (not bad for a sack of goo!). I even have a box jelly on the cover of my debut popular science book, Venomous. So I was taken aback by the casual implication that jellies wield poisons, as if they passively wait to be assaulted before delivering their terrible toxins. I know that Pokémon are fictional creatures, but that’s no reason to use biological terminology incorrectly!

It got me thinking: how appropriately named are the “Poison” Pokémon in Pokémon Go**? So I did a little research… Clearly, Professor Willow isn’t a toxinologist.

Venom-Type Pokémon

There are 10 purely Poison-type Pokémon and 23 Dual Poison Type Pokémon in Pokémon Go, many of which are more accurately described as Venom-type.

Perhaps the most obviously venomous Pokémon are the Nidoran progressions (male and female). The young females are described as having “barbs that secrete a powerful poison” which are “thought to have developed as protection.” And on top of that, “when enraged, it releases a horrible toxin from its horn.” So Nidoran are both offensively and defensively venomous, kind of like cone snails! Both male and female Nidoran can start with the Poison Sting and Poison Fang attacks, and males can additionally begin with Poison Jab, all of which are more appropriately described as venomous actions.

Once they “evolve” (yeah, another misused biology term; more akin to evolution of stars than animals), Nidorino and Nidorina are able to fold down or raise their venomous barbs at will, according to Pokémon lore. Once they become Nidoking and Nidoqueen, the barbs seem to reduce or disappear; they have hard scales and are brutish enough not to need a venomous defense, and it appears as though their barbs are minimized accordingly.

Male and female Nidoran progressions—I'd include their final forms, but I haven't caught/evolved them yet (Hey, I'm only Level 14!)

Male and female Nidoran progressions—I’d include their final forms, but I haven’t caught/evolved them yet (Hey, I’m only Level 14!)

There are other Poison-type Pokémon that can deliver a Poison Sting: Weedle (tricked-out bee larvae), Ekans and Arbok (Pokémon’s snakes), and my favorite Tentacool and Tentacruel (the different evolutions of jellies). In addition to the Nidoran progressions, Poison Jab is used by Beedrill (Poké-bees) and the Poké-jellies, and Poison Fang—clearly venomous bites—are wielded by the Poké-snakes, Venonat and Venomoth (appropriately named bugs), and Zubat and Golbat (Poké-vampire bats, as Golbat specifically flies around at night, “seeking fresh blood”; real vampire bats are considered venomous).

According to the greater Pokémon universe, Poison Sting and Poison Jab have a ~30% chance of “poisoning” the target, which is pretty realistic. It’s estimated that only 30% of scorpion stings involve venom injection, for example. Similarly, Poison Fang has a ~50% chance of poisoning; scientists suggests anywhere from 25 to 50% of snake bites are dry (no venom), so 50% isn’t unreasonable. Also somewhat accurately, there is a difference in severity between toxic Pokémon stings and bites—Poison Fang makes a victim “badly” poisoned, while Poison Sting and Poison Jab only “poison.” Defensive venoms tend to be much less toxic than offensive ones, so the distinction is warranted.

Several Pokémon can attack with Toxic Spikes, where they are able to lay toxin-laden spikes at their foe’s feet. I don’t know of any animals in our world capable of doing this, but I would categorize it as a venomous ability given that the toxin and the spikes are presumably biologically produced by the animal, and the toxins are delivered through wounding. In addition to the Nidoran progressions, Beedrill and the Poké-jellies, this attack would make Cloyster, a mollusk Pokémon that is not listed as a Poison-type, venomous as well (perhaps the bivalves’ answer to cone snails?). And then there’s Cross Poison, a slashing move that only has a 10% chance of poisoning the enemy, employed by the adorable non-Poison-type Paras and Parasect (hermit crab-like Pokémon with mushrooms growing into their back, somewhat similar to how certain barnacles parasitize crabs).

Total: 19 Venom-Type Pokémon

Toxungen-Type Pokémon

You might be tempted to let the term poison slide for many of the Poison-type Pokémon, as they are, technically, armed with toxins that are absorbed, inhaled or ingested; but according to Nelsen’s definitions, they are not poisonous. They’re more accurately described as toxungenous, as their toxins are used as active weaponry.

There are lots of toxungenous attacks in the Pokémon universe: Poison Gas, Smog, Acid, Gastro Acid, Acid Spray, Poison Powder. The first two are examples of toxic inhalants; in both cases, a toxic gas is used (Poison Gas poisons but deals no initial damage, while Smog damages but only poisons 40% of the time). These are employed by Grimer and Muk, and Koffing and Weezing (Poison-type), as well as Drowzee and Hypno (Psychic-type), and Magmar and Flareon (Fire-type). But they should be more accurately employed by Bug-type Pokémon, for there are ants in Africa that have perfected the art of toxic cloud attacks. The African myrmicine ants (Crematogaster striatula) can kill their termite prey without touching them using vaporized toxins that they emit from specialized glands.

Acid-armed Pokémon are able to spit, spray, or otherwise fling acidic fluids at their targets, causing caustic damage. Those equipped with such attacks include the Poké-snakes, Poké-jellies, as well as Oddish, Gloom, Vileplume, Bellsprout and Weepinbell—all Poison-type Poké-plants. And lest you think flinging acid is an unrealistic ability, let me introduce you to Stumpy, a humble vinegaroon:

That's 85% acetic acid comin' at ya! Great footage by BBC Earth Unplugged

That’s 85% acetic acid comin’ at ya! Great footage by BBC Earth Unplugged

Vinegaroons (also called whip scorpions, although they are not true scorpions) are defensively toxungenous, using a potent acidic spray which smells like vinegar (hence the name) to turn away potential predators. The spray smells like vinegar because it contains the same chemical, acetic acid, but at much higher concentrations. The vinegaroon’s spray consists of ~85% acetic acid—15 times the concentration of vinegar—which not only makes it smell awful, it’s also corrosive enough to erode. The acid is aided by caprylic acid and certain ketones, which help it penetrate through the toughest of skins. So, it’s perfectly believable that some Pokémon can spray acid.

Some Pokémon are able to produce a toxic dust rather than a liquid that they fling at enemies (Poison Powder). Toxungenous dusters include the Poké-plants and Paras and Parasect, Venonat and Venomoth, as well the Poison/Grass-Type reptilian Pokémon Bulbasaur, Ivysaur, and Venusaur. The attack is also performed by the non-Poison-Type Butterfree (Poké-butterfly), Exeggcute (egg-like creatures that are more accurately described as seeds), and Tangela (a ball of vines).

The case could be made that there are even more toxungenous Pokémon. The vilest, grossest Pokémon are able to attack their enemies with waste and garbage using moves like Sludge, Sludge Wave, Sludge Bomb, and Gunk Shot. In the Pokémon universe, these moves are employed by Pokémon inspired by nonliving stuff: Grimer and Muk, which are described as living pollution, and Koffing and Weezing, embodied illnesses, and they gain their vile attacks by consuming garbage. According to the definitions set forth by Nelsen and his colleagues, these Pokémon would be facultatively toxungenous, as they are only toxic when provided with a toxic diet.

Total: 27 Toxungen-Type Pokémon

Truly Poison-Type Pokémon?

Almost all of the Poison-type Pokémon are venomous or toxungenous. There is, however, one move which is vague enough that it could make for truly poisonous Pokémon: Toxic. The move is described as “A poison move with increasing damage,” or in other versions: “Poisons the foe with an intensifying toxin,” and “A move that badly poisons the foe. Its poison damage worsens every turn.” Since there is no description as to how the toxin is introduced—no reference to spraying, biting, stinging, etc—then it seems reasonable to believe that the toxin(s) are simply on or in the Pokémon and are delivered somewhat passively, by the enemy brushing up against the Pokémon, or biting it. Even a video of the move in various game versions doesn’t clarify—in one case, it appears Toxic is toxungenous, as clouds of toxins move from one Pokémon to the other, but in most of the other cases, the toxic effect just seems to appear. Then again, the Pokémon are never shown in contact with one another in battle, even during more intimately physical moves, so we wouldn’t see it if the toxin was transmitted by contact.

In Pokémon Go, only the Poké-plants Oddish and Gloom are potentially-armed with Toxic, which makes a lot of sense for a poisonous ability: though there are certainly poisonous animals, plants have dominated the toxic world. By nature, plants are at a disadvantage when it comes to becoming someone else’s meal: they don’t (generally) move. With their roots firmly planted, they are unable to flee. So instead, they have evolved chemical defenses to ward off potential grazers. The most poisonous plants can kill us in surprisingly small doses. So it’s fitting that, if there is a poisonous move in the Pokémon world, it’s used by plants.

Example of toxic plant: the Manchineel tree. In Spanish-speaking countries, it is known as la manzanilla de la muerte or arbol de la muerte, which translate to “the little apple of death” and “tree of death.” Photo by Scott Hughes

Example of truly poisonous plant: the Manchineel tree. In Spanish-speaking countries, it is known as la manzanilla de la muerte or arbol de la muerte, which translate to “the little apple of death” and “tree of death.” Photo by Scott Hughes

In addition, at least some Pokédex descriptions of Venonat, Venomoth, Grimer, Muk, Koffing, and Weezing suggest that they are also poisonous; depending on the game version, they are imbued with toxic lore. For example, in Pokémon Silver, it is noted that accidentally touching Muk, “will cause a fever that requires bed rest.”  In Pokémon HeartGold, the Pokédex warns that Koffing’s “thin, filmy body is filled with gases that cause constant sniffles, coughs and teary eyes.” As these are pathophysiological injuries caused by coming in contact with the Pokémon, these ones are truly poisonous beasts. And there are more: in Pokémon Silver, Venonat has “poison that oozes from all over its body.” Venomoth has poisonous wing scales: in Pokémon Yellow, “The powdery scales on its wings are hard to remove. They also contain poison that leeks out on contact” and in Pokémon Stadium, “it scatters the powder with every flap. So you may be poisoned if you are downwind.” But whether these ones truly count as poisonous is unclear, as their descriptions in Pokémon Go do not mention these traits.

Total: 2, maybe several more, Poison-Type Pokémon

A Toxin By Any Other Name…

It might seem pedantic to point out the differences between toxin types, and obviously, this post is meant to be somewhat lickitung-in-cheek. But this “silly” stuff does matter; game and other fictional representations of nature can have tremendous impacts on our understanding of life and even how we view science or conservation efforts. Games like Pokémon are entertainment, but they’re so much more than that. Just look at the impacts the game is already having: people are getting more outdoor exercise, making new friends, engaging with non-cartoon wildlife, and connecting with their world in new and exciting ways.

Now, if you’ll excuse me… there’s a Squirtle around here somewhere, and I have a puppy in desperate need of a nice, long walk (which doubles as a charitable donation to the shelter that cared for her!). Gotta catch ’em all…


A special thank you to David Nelsen for his expertise on toxins, poisons, venoms and toxungens, and to my ultra-geeky boyfriend, Jake Buehler, who served as my Pokémon expert. 

* Substances that are not toxins can be toxic, though; the word toxic does not refer to dose. So water is toxic if you pound down dozens of gallons in a matter of minutes, but despite that, it’s not a toxin. 

** There are lots more Pokémon in the Pokémon universe from the cards, manga, anime and games—Pokémon Go has only a small subset of the total Pokémon.

CATEGORIZED UNDER: Ecology, More Science, select, Top Posts
  • Christopher Lund

    Tentacool (and several others) may also have the “Liquid Ooze” ability, which poisons any Pokémon that tries to absorb its HP using a move like “Absorb” or “Mega Drain”. So in that sense they are also (sometimes) poisonous.

    • John C

      Get a girl friend, now.

      • Cajun Exile

        He has never spoken to a woman, other than his mother, without first giving a credit card number.

        • Paul

          Probably had to put down a deposit even with Mom.

    • Christie Wilcox

      Good catch! As a n00b to Pokémon, I don’t now the ins and outs of the games… I wonder if there are abilities like this in Pokémon Go?

    • Christopher Lund

      Ah, no! I was just hoping to add to the fun, and missed the bit where this was specific to Go. Sorry!

      • Christie Wilcox

        It’s ok — I branched out a little outside my self-described box of Go only in the post anyway :).

  • Uncle Al

    Pokémon? feh Collect all 30 crores of Hindu gods.

    • Cajun Exile

      That would be a lot of chariots…at Ratha-Yatra they only collect four…it would deforest the Amazon…chronically impoverished rapidly laterized soil not withstanding

      • Uncle Al

        Lakshmi – good! “भद्रैषां लक्ष्मीर्निहिताधि वाचि”
        Lakshmi’s abode – warm, but not so good.

  • Mesmer7

    this crap doesn’t belong in a science related magazine.


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About Christie Wilcox

Dr. Christie Wilcox is a science writer and postdoctoral scholar at the University of Hawaii. She freelances for major media outlets including The New York Times and Popular Science. Her debut book, Venomous, releases August 2016 (Scientific American/FSG Books). To learn more about her life and work, check out her webpage or follow her on Twitter, Google+, or Facebook.


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