Based on one of the comments in my previous question about What is the max size for underground creatures before the square-cube law takes a toll?

Makes me want to know the limit size for a long creature like a snake/worm before their own body crushes them or their organs don't function properly.

And I know there's a prehistoric snake like titanoboa that is very huge, but I still want to know: Is that the limit a snake/worm can be, or theoretically can it be even longer and bigger than that and still function?

Feel free to edit the tag to be more appropriate.

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    $\begingroup$ Possible duplicate of: worldbuilding.stackexchange.com/questions/78949/… $\endgroup$
    – nzaman
    Nov 13, 2019 at 14:10
  • $\begingroup$ @nzaman that questions seems more focus on how his giant snake get food rather than asking about limit size. $\endgroup$
    – Li Jun
    Nov 13, 2019 at 14:26
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    $\begingroup$ check apaul's answer and my comment to the OP $\endgroup$
    – nzaman
    Nov 13, 2019 at 15:14

3 Answers 3


The main problem with snake would be not size and weight, but interchange with external media: feeding, breathing, etc. Snake is cheating with square-cube, making it square-square or even square-linear (if it is does not increase its width).

There theoretically can be a kilometers-length snake of several centimeters wide in terms of structural stability. It even will be able to move! (Each "section" of a snake is self-propellant)

But then comes a problem - how to keep tail nutrient? Almost anything this snake eats would digest in several first meters! And then next several meters of tissue would take all nutrition to itself.

So the snake is just an envelope around digestive tract. And the length of digesting tract is determined by the size of its pray and the length of digestions.

If we imagine snake capable to swallow and digest brachiosaurus (up to 20m long), then it need to have times more length - say about 100m but not that much - less then 200m. Snakes can stretch a lot (tenths of times) so "empty" snake width would be less then a meter - about 30-50 cm in common and 1m in widest parts. This snake would eat one brachiosaurus in couple of years and then lay still for most of the time digesting. It is hard to imagine conditions were this snake would not be eaten by other predators, but lets say it has perfect adaptive camouflage (chameleon-like), and, say, spread some predator-repelling smell. (but I still hardly imagine how this thing can evolve!)

So we can have 150m length, 0.5-1m thick, about 10-15 t snake, which is almost invisible, can swallow brachiosaurus and then lay for years digesting it (and spreading terrible odor in process).

There can be more than that - but then you need a bigger prey to feed it.

In current conditions largest snake would be an elephant or giraffe (largest length)-eating snake with size about 20-30 m length, 10-30 cm thick, with weight about 1-2t. A "Doubletitanoboa".

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    $\begingroup$ Just to illustrate: just compare size ( length and and total mass) of any major cable (like cross-antlantic) or gas/oil tube ore bidge - they can be practically any length and no "normal" building can come close to this parameters. $\endgroup$
    – ksbes
    Nov 13, 2019 at 9:02
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    $\begingroup$ Are you sure that having a rotting carcass in the bowel for a couple of years is not going to cause any issue? $\endgroup$
    – L.Dutch
    Nov 13, 2019 at 9:17
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    $\begingroup$ @L.Dutch-ReinstateMonica most reptiles already eat at low intervals, some crocodiles for example have one big feast a year when the Wildebeast migration passes. They have a trick where they can produce lots of gastric acid at once so the meal is sterilized quickly and can then be digested at leisure. $\endgroup$
    – Borgh
    Nov 13, 2019 at 9:31
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    $\begingroup$ Would there be a limit due to nerve impulse travel distance? I've tried to look to see if there is a limit and can't find one, but I'm guessing this would be part of the reason the larger dinosaurs had sub-brains? $\endgroup$
    – Riddles
    Nov 13, 2019 at 10:05
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    $\begingroup$ @Riddles ANR is capable of many reflex action (ex,vomiting), so snake can react, and then relize that smth happen. Snakes already do it for bitting, for example. Cooldblood brain is to slow to bite fast, so snakes has special "fast nerve loop" connected to its IR sensors, wich activeted when snake is hungry. So from POV of snake - it laying in the sun, then bom - it is on someone finger and snake is frightened and supprised even more then (ex)owner of that finger. $\endgroup$
    – ksbes
    Nov 13, 2019 at 11:00

My answer to this question: Can a land-based organism get to be at least 100 ft. in length and still be plausible?1 may be useful.

The Longest known land animals, sauropodmorph dinosaurs, had thick bodies, but their long slender necks and tails were a bit snakelike.

The longest known sauropodmorph dinosaurs were estimated to have maximum lengths over 100 feet. And the legendary lost fossils of the possibly largest dinosaurs of all indicate a maximum length of up to 190 feet for the single specimen of one species.

So a snake like creature 100 feet long, 150 feet long, or even 200 feet long would have a lower body mass than the largest known land animals. But it wouldn't have legs to support its body above the ground, and so it's body would have to be strong enough to slither along the ground, and to avoid being crushed by gravity.

Some large snakes, like anacondas, actually live in mud and fresh water, and it might be theoretically possible for fresh water snakes to be much larger than anacondas and titanaboas.

I note that earthworms are snake or worm like creatures that burrow in the ground.

Crytozoolologist Ivan T. Sanderson once speculated that some northern European water monsters might be gigantic cacelians. Caecelians are limbless amphibians who live underground and underwater and look like earthworms or snakes. This theory was mentioned in David Drake's fantasy Arthurian novel The King's dragon 1979, revised as The dragon Lord 1982.

There are many snake like and worm like creatures in the oceans, with a big range in size.

Sea snakes are rather ordinary sized and are very venomous.

Many reported sea monsters or "sea serpents" were described as being serpentine. Many whales are rather slender, so a sea creature as wide as a whale but two or more times as long would probably seem serpentine.

Here is a link to a question about the size and anatomy of giant sea "serpents":

How large could my sea serpents be?2

There are many types of marine "worms".

The bootlace worm, Lineus longissimus has a very narrow and very long body.

Bootlace worms may grow very long but are usually only 5 to 10 millimetres (0.20 to 0.39 in) in width

In 1864 a specimen washed ashore in the aftermath of a severe storm by St Andrews, Scotland, which was more than 55 m (180 ft) long,[6] longer than the longest known Lion's mane jellyfish, the animal which is often considered to be the longest in the world. However, records of extreme length should be taken with caution, because the bodies of nemerteans are flexible and can easily stretch to much more than their usual length.


The lion's mane jellyfish, also known as the giant jellyfish or the hair jelly,3 is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. It is common in the English Channel, Irish Sea, North Sea, and in western Scandinavian waters south to Kattegat and Øresund. It may also drift into the southwestern part of the Baltic Sea (where it cannot breed due to the low salinity). Similar jellyfish – which may be the same species – are known to inhabit seas near Australia and New Zealand. The largest recorded specimen was measured by Alexander Agassiz off the coast of Massachusetts in 1865 and had a bell with a diameter of 7 feet (2.1 m) and tentacles around 112 feet (34 m) long,4 although it was incorrectly reported by the Guinness Book of World Records that the sighting occurred in 1870 and that the jellyfish measured 120 feet long. Lion's mane jellyfish have been observed below 42°N latitude for some time in the larger bays of the east coast of the United States.


If a jellyfish with tentacles 112 feet long had two pointed straight apart, their tips would be 224 feet apart.

I find it easy to believe in the theoretical possibility of snake like or worm like sea creatures hundreds of feet long.

Added 11-15-19. And also see this question:

What kind of planet could have giant sand worms?5

It asks about sand worms, like in Dune. And maybe some of the answers will discuss the possible size range of hypothetical sandworms on an alien planet.


ksbes makes a good point that the limit on length is likely to be logistical rather than structural. It's a bit like how the height of skyscrapers is limited by the need to devote more and more space to elevator shafts.

You can get around this by having all the relevant systems distributed along the worm's length – e.g. hearts, brains, and mouths spaced every few meters – but that raises the question of why such an arrangement would be advantageous over a bunch of smaller independent worms.

Another issue with being very long compared to your width is that, like a skein of yarn, you have the possibility (indeed, the likelihood) of ending up irreversibly tangled as you move around. I suspect the processing power required to either avoid that, or to undo a large tangle, would very quickly become infeasible for a free-roaming worm whose length was more than a few hundred times its width.


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