Main Page

Explain xkcd: It's 'cause you're dumb.
Revision as of 12:19, 18 December 2013 by Davidy22 (Talk | contribs)

Jump to: navigation, search

Welcome to the explain xkcd wiki!
We have an explanation for all 1397 xkcd comics, and only 49 (4%) are incomplete. Help us finish them!

Latest comic

Go to this comic explanation

Snake Facts
Biologically speaking, what we call a 'snake' is actually a human digestive tract which has escaped from its host.
Title text: Biologically speaking, what we call a 'snake' is actually a human digestive tract which has escaped from its host.


The comic lists a few 'factoids' about snakes, ranging from the mildly informative to the strictly tongue-in-cheek. The first factoid references the hypothesis that snake venom was an evolutionary development of saliva that, over time, gradually became more toxic as snakes with saliva that was able to assist in subduing their prey possessed an evolutionary advantage. It then posits that the evolutionary branch that developed into venomous snakes began with a snake whose mutation gave him a mouth that was 'slightly more gross than usual'.

The second factoid references the 'longest snake in the world', citing a South American habitat. Given the habitat listed, it is possible the comic is referring to the Green Anaconda (Eunectes murinus), but the Green Anaconda, while an impressive creature and one of the longest snakes in the world, is generally not as long as the Reticulated Python (Python reticulatus) of Southeast Asia, which is generally recognized as the world's longest snake, though not its largest by mass. The factoid then states that the world's longest snake is 'believed to be over 60 years old'. As Anacondas generally do not live beyond 20 years in captivity, and likely less in the wild, the factoid appears to be in error on this count also. Its wording seems intended to imply that the snake in question is not a species, but rather a single specimen. Also, this information can be disappointing, as one could expect to learn about the length of the snake, not his age.

Additionally, the comic illustration accompanying the second factoid colors in a 'habitat range' on a map of South America that is snake-shaped, possibly implying that when it states 'The longest snake is found in Brazil into Chile and Peru' that this snake is so long that it literally stretches from Brazil, Chile, and Peru, and that the 'habitat' shaded on the map is, in fact, this mammoth snake's silhouette.

The final factoid is entirely tongue-in-cheek, beginning with a typical factoid trope in which a collection of related items are laid end-to-end, then the length is compared to something else in a way intended to surprise the reader that the collection of items is indeed, so extensive (literally and figuratively). For example, "If you laid all the veins and arteries in the human body end-to-end, they would stretch 60,000 miles". The third factoid takes the form of that trope and turns it into a joke, "If you laid all the bones in a snake end to end, you would have a snake." The resulting length would not be a surprise to anyone. Obviously, you would not have an entire snake, literally, but you would have a skeleton that was recognizably that of a snake and could reasonably be referred to as 'a snake', albeit a skeletal one.

The title text presents the amusing idea that 'snakes' as we know them are not, in fact, a suborder of reptiles but are instead human digestive tracts that, rather than being a system of organs, are creatures capable of escaping from their 'host' human and living independently. The idea seems to follow from the superficial resemblance between snakes and the human digestive tract as long, roughly tubular collections of animal matter, which can process the food entering the top end, and getting rid of the waste in the other end. Actually the human digestive tract is essentially a hole that runs through the body, closed off most of the time only by sphincters, and digestion thus can be said to take place outside the body. Nutrients are absorbed across membranes via osmosis, active transport, and diffusion.


  • Randall had previously posted an incorrect map, that included the snake's habitat in Bolivia instead of Peru. [1]


Snake Facts:
Snake venom evolved from saliva, which means it all started with a snake whose mouth was slightly more gross than usual.
[Picture of a snake below the text above]
Snake: Hi guys!
Off-panel voice: Eww, it's Frank.
[Map of South America with gray shade in the form of a snake. Text to the left of it]
The world's longest snake is found in Brazil, Peru and Chile. It is believed to be over 60 years old.
[Picture of a snake skeleton between the first and the second of the lines below]
If you laid all the bones in a snake end-to-end,
you would have a snake

Is this out of date? Clicking here will fix that.

New here?

Last 7 days (Top 10)

Lots of people contribute to make this wiki a success. Many of the recent contributors, listed above, have just joined. You can do it too! Create your account here.

You can read a brief introduction about this wiki at explain xkcd. Feel free to sign up for an account and contribute to the wiki! We need explanations for comics, characters, themes, memes and everything in between. If it is referenced in an xkcd web comic, it should be here.

  • List of all comics contains a table of most recent xkcd comics and links to the rest, and the corresponding explanations. There are incomplete explanations listed here. Feel free to help out by expanding them!
  • We sell advertising space to pay for our server costs. To learn more, go here.


Don't be a jerk. There are a lot of comics that don't have set in stone explanations; feel free to put multiple interpretations in the wiki page for each comic.

If you want to talk about a specific comic, use its discussion page.

Please only submit material directly related to —and helping everyone better understand— xkcd... and of course only submit material that can legally be posted (and freely edited). Off-topic or other inappropriate content is subject to removal or modification at admin discretion, and users who repeatedly post such content will be blocked.

If you need assistance from an admin, post a message to the Admin requests board. <a href="" rel="publisher">Google+</a>

Personal tools


It seems you are using noscript, which is stopping our project wonderful ads from working. Explain xkcd uses ads to pay for bandwidth, and we manually approve all our advertisers, and our ads are restricted to unobtrusive images and slow animated GIFs. If you found this site helpful, please consider whitelisting us.

Want to advertise with us, or donate to us with Paypal or Bitcoin?