Basilisks: What Makes These Harry Potter Beasts So Fantastic?

Monsters of fantasy, even those made of flesh and blood, are often defined by an otherworldly trait that defies what real-world biology is capable of. Take as a prime example, the Serpent of Slytherin itself: the Basilisk.


And beyond just this snake’s petrifying vision, the roster of mythical and magical abilities goes on — fire breath, multiple heads, invisibility, there are hundreds of attributes and adaptations spread across the animal kingdoms of fantasy… Yet amazingly enough, many of these fabrications tend to be grounded in actual, measurable biology.

These comparisons can be enriching and sometimes quite silly, but the goal of this analysis is never really to disprove the plausibility of fantasy — trying to do so is pointless. The true aim is to make connections that didn’t exist before; to inspire wonder and amazement at the quirkier corners of our actual natural history. With almost uncanny consistency, the traits seen in these fantastic beasts fall in lock-step with observations in the real world. Case-by-case, the deeper you look, you’ll find real-world biology that could have been pulled straight from the pages of a wizarding world. And Harry Potter’s basilisk is a perfect place to start.


Oh how the times have changed.

Now it would be wrong to give basilisk credit to J.K. Rowling alone (or actually, at all). There are records of the mythical basilisk dating almost 2000 years ago, and trust me the Harry Potter version takes plenty of creative liberties on the original. These ancient stories describe the monster as “small” and the sworn enemy of the weasel, but there are enough common threads to see where Rowling took her inspiration. Oh and not to mention that the name also refers to a real-life South American lizard. Decidedly not as deadly.

One trait is very consistent though through all the myth and lore, right up to the serpent’s defining trait in The Chamber of Secrets:

“Of the many fearsome beasts and monsters that roam our land, there is none more curious or more deadly than the Basilisk, known also as the King of Serpents. This snake, which may reach gigantic size, and live many hundreds of years, is born from a chicken’s egg, hatched beneath a toad. Its methods of killing are most wondrous, for aside from its deadly and venomous fangs, the Basilisk has a murderous stare, and all who are fixed with the beam of its eye shall suffer instant death. Spiders flee before the Basilisk, for it is their mortal enemy, and the Basilisk flees only from the crowing of the rooster, which is fatal to it.” — Excerpt from “Most Macabre Monstrosities”, a fictional book inside a real Harry Potter book. Ugh.

I’m giddy about diving into the meat of this, but let’s first tick off a few stray questions. In the canonical Harry Potter universe this basilisk grows to be 50 feet long, and yes that size has been observed in real-world snakes. Also yes it is possible for eggs of one species to hatch (deviously) in the nest of another, and yes it is possible for naturally occurring chemicals to repel spiders. I’ll let the death-by-rooster thing slide.

But I want to get on to petrification, the real crux of the basilisk’s strength and a quite-handy plot device. Interpret the magic however you like — to stun, to paralyze, to turn into stone — but petrification is rampant throughout myth, fantasy, and storytelling across the ages.

The basilisk, Medusa, and the White Witch of Narnia. One of these things is Tilda Swinton, I’ll let you guess.

Perhaps there’s something innate to our human psyche that makes us terrified of a monster that can freeze us solid from afar. Or, perhaps, our ancestors observed the phenomenon in nature and injected some real-life science into their early threads of mythology. In either case, it hasn’t been until the last few decades that the evidence has piled up: petrification is real. Observed in the natural world and documented in spades on the internet.

And no it’s not paranormal in the slightest. Just some cool critters.

The first and most obvious comes from certain types of venom. Some snakes produce dendrotoxins that wreak havoc on the nervous system and cause debilitating muscle paralysis; likewise with certain scorpions and other insects as well. But this is common knowledge — what about an ability like that of the basilisk, to paralyze from a distance without actual physical contact.

Well from here we head underwater (not uncommon on this blog) and find three examples of animals that stun, paralyze, or petrify to get their dinner. First is probably the most widely-known, but still amazing: the electric eel. We’ve observed for some time that the eels are capable of stunning pray with high-voltage shocks, but it wasn’t until 2014 that the mechanism was more thoroughly understood. Even without being in close proximity, the shocks are able to mimic the type of electricity that controls muscle movement, thereby rendering fish defenseless… at least from a short distance.


And it gets cooler. Certain species of Cuttlefish petrify in a different way: hypnosis. These animals will create pulsating patterns in their color-changing chromatophore cells, most often used for camouflage, to lull prey into a trance before striking. No electricity or venom required.

But let’s go one step cooler than even that: the pistol shrimp.

Bam. The pistol shrimp nucleates the water around its claw and sends a shockwave of pressure toward any prey unlucky enough to be caught in its sights. An entirely distinct third method of petrification from afar.

Underwater species are given an interesting handicap in this evolutionary arms race, however. Predators and prey live within a liquid medium that can easily transfer energy — like shrimp pressure or eel voltage — in ways that air simply cannot. That cuttlefish hypnosis though, that’s the real deal. Also shoutout to the Cone Snail that actually stuns its prey with a venom that lowers insulin levels and induces a near-catatonic state. It’s not a distance-stunner like these other creatures, but still damn impressive.

So the basilisk freezes Hogwarts students from afar with just a simple gaze. Surprisingly not as impossible as it may have always seemed. There are indeed some elements of fantasy that we cannot justify with science however hard we try — like the fact that a reflected gaze stuns but a direct one kills — but that’s not the point, remember? What we’re trying to uncover are the cool, creepy, mysterious corners of our own natural world. If mythology is able to give us a gateway into the conversation, that’s even better.

What’s most amazing to me is that these biological discoveries came centuries later than the earliest stories of the basilisk and petrification. Something that ancient storytellers once thought of as complete fantasy turned out to be much more real than they could have ever understood. So what other Harry Potter beasts will we eventually, after decades more of scientific research, be able to “prove” as possible next… Petrals? Centaurs? Only time will tell.

But the next time you’re checking out a fantasy movie or novel, give mother nature a phone call and check in. Always a great conversation.

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