Poisonous and venomous creatures, a handy guide.

A Nitpicker’s Guide to Venomous and Poisonous Creatures

A Nitpicker’s Guide to Venomous and Poisonous Creatures

Wild Things
Slate’s animal blog.
Feb. 16 2016 12:48 PM

A Nitpicker’s Guide to Venomous and Poisonous Creatures

Slow loris.
Slow loris.


“Are there any poisonous snakes around here?” a friend asked me while on a camping trip in Pennsylvania.

There are no poisonous snakes here, I replied, because snakes are venomous, which means they inject venom into you. Frogs, beetles, and pufferfish are poisonous, which means you shouldn’t eat them.


After another five minutes of me explaining why the words poisonous and venomous are not interchangeable, I’ll wager my buddy would have preferred the snakebite.

Honestly, I wasn’t trying to be a pedant. I just find venomous and poisonous creatures to be fascinating. And once you get me going, well …

For instance, did you know that only about one-seventh of all species of venomous snakes have hollow, hypodermic-needle fangs? The rest use simple grooves on the outsides of their teeth to conduct the venom where it needs to go through the magic of physics. Toothy grooves are also how the Gila monster of the Sonoran Desert and the solenodon, a venomous island shrew of the Caribbean, lay their victims low.

Poisonous animals have their own secrets, of course. Some, like the rough-skinned newt of the Pacific Northwest, have specialized glands that produce anti-predator compounds. In the event that a hungry bullfrog comes along and swallows it whole, the newt can secrete a neurotoxin that scrambles the attacker’s nervous system. In time, the frog’s brain loses its ability to communicate with its body. This causes paralysis, suffocation, and death.  


But the newt does not die with the bullfrog. Oh, heavens no. The newt walks up the dead frog’s gullet and pops out into the sun singing the chorus to “Wrecking Ball.”

Some poisonous creatures aren’t even born that way. They have neither neurotoxic glands nor hollow fangs. For these animals, power is not given but seized.

In 1989, a researcher named Jack Dumbacher cut his hand while trying to free a small bird from a mist net in New Guinea. Dumbacher thought the wound felt weirdly hot, but didn’t worry much about it until he put the cut up to his mouth (as one does). When his lips and tongue started to tingle and burn, and continued to do so for several hours, Dumbacher realized that he’d discovered the world’s first poisonous bird—the Pitohui.

On its own, the Pitohui is no more lethal than the oriole it vaguely resembles. But then, orioles don’t eat beetles laced with batrachotoxin. So far as scientists can tell, the Pitohui has evolved a way to absorb the poisons found in Choresine beetles and appropriate them for its own defense. Both its feathers and flesh carry the telltale tang of batrachotoxin.


The Pitohui is far from the only bird with this trick. The spoor-winged grouse also gets its zing from toxic beetles. Ruffed grouse and Australian bronzewings acquire poison from plants. And the European quail gets its punch from hemlock seeds. (My colleague Megan Cartwright wrote about poisonous birds last June.)

In another example, the African crested rat becomes poisonous after chewing on tree bark and then slathering its noxious saliva all over its body. What a lovely creature. Then there is the nudibranch—a soft-bodied sea slug that eats anemones for a living. Normally, this would be a dangerous proposition as the tentacles of anemones are lined with thousands of stinging cells called nematocysts. But a special coating of chitin in the nudibranch’s throat allows it to swallow the stinging cells without a problem, sort of like Homer Simpson at a chili cook-off. Further down the digestive tract, still more mollusk magic enables the slug to sequester any stingers that haven’t yet fired and then load them into rows of Funkadelic dreadlocks on the creature’s back. Then, whenever a predator comes along, the sea slug can fire the stolen cells out of its stalks like “tiny toxic grenades.”

By the way, this would make the nudibranch and the anemones it eats venomous, as opposed to poisonous. If you look at nematocysts under magnification, you’ll see that they resemble microscopic hellfire missiles. This is why you don’t have to eat an anemone or jellyfish to get hurt by one. The burn comes to you.

There are also animals that defy classification. Frogs possess toxin-producing glands, which make them all poisonous to some degree. But in 2015, researchers working in the thorn forests of Brazil discovered that two species of frog have turned their poison into venom. These frogs have secret skull razors: When they’re backed into a corner by a snake or unwitting biologist, subcutaneous spines pop through the frogs’ lip skin. What’s more, the spines are anchored in poison glands that produce a white mucous more toxic than pitviper venom. So are the frogs poisonous or venomous? Well, the only biologist who has ever been poked by one argues they are both.


There’s also a Spanish newt that double-majors in poison and venom. Instead of sprouting face spines, the newt flexes its ribs until they burst out of its chest, which is just all kinds of metal.

Our own family tree even boasts a species with venom-poison identity issues: The loris.

Lorises look like emaciated Ewoks, but people think they’re very cute. Unfortunately, that perception has turned the bug-eyed primates into YouTube stars and fueled an exotic pet trade that brutalizes individual lorises and threatens the species’ existence in the wild. Which is all the more disconcerting when you learn just how ill-suited these animals are for life in a purse.

Lorises have modified sweat glands in their armpits that produce a protein similar in chemical structure to cat allergen. When frightened, the loris raises its arms overhead—a posture that some have mistaken for a desire to be tickled, but is in fact more similar to the cocking of a pistol. To activate its venom, the loris must lick its pits to mix the oily secretions with its saliva. Then it delivers the dose with its tiny teeth. (Loris venom is thought to cause a variety of ailments in humans, including anaphylactic shock and even duck face.)


As to how to classify this critter on the venom-poison axis, loris expert Anna Nekaris says they’re definitely the former and possibly the latter. A single Javan slow loris has been observed slathering its young in its secretions before leaving it to forage, leading scientists to believe the loris’ venom may also work as an external predator deterrent. Another possibility is that the toxic spit works as insect repellent, since lorises have been found to have lower ectoparasite loads than other primates.

Obviously, labeling an animal as venomous or poisonous has no effect on that creature’s capacity to eff you up. But knowing exactly how that creature’s weapons work might help you avoid calamity.

By the way, I was wrong when I told my friend there are no poisonous snakes. In 2007, scientists discovered that the Asian tiger snake can secrete defensive steroids out of its neck after eating toxic toads. The snake is both poisonous and venomous.

But the pedant in me would point out I was right about one thing: There are no poisonous snakes in Pennsylvania. (Yet.)