A 15-meter anaconda?

March 13, 2019 • 11:15 am

by Greg Mayer

Matthew Cobb sent me and Jerry a Tweet that contained this video, purportedly showing a 15 meter long anaconda (Eunectes murinus) in Brazil. Commenters on YouTube suggest it’s a fake, but I see nothing to indicate that. My Portuguese is very poor: I can hear the narrator say “cobra” (=snake), “anaconda”, and “sucuri”– this last is similar to a Brazilian Portuguese word I know, “sucuriju”, which means, at least roughly, “boa”, and is used in the combination “sucuriju gigante” for really big anacondas. Perhaps a Lusitanophone reader will favor us with a fuller translation. (“flurudha.com”, which appears at the lower right of the video, is a news-of-Albania-in-English site; I don’t know what’s up with that.)

It’s a big snake, but it’s hard to tell how big it is– there are no items of known size to compare it to. If the exact location could be determined, and the width of the stream measured, that could provide a basis for an estimate (although the shore is pretty featureless, and stream width could vary widely over time depending on seasonal rainfall patterns). There are many stories of huge anacondas. The account of Percy Fawcett, a British explorer is well known, having been featured in Bernard Heuvelmans’ work, and illustrated by his son, Brian; it was supposed to be 62 feet long.

From Heuvelmans (1959).

Heuvelmans also credulously records reports of 130 foot long anacondas, which he supposes might be an unknown species, distinct from the anaconda. But how big do anacondas actually get?

This question is intimately tied up with the question of how big reticulated pythons (Python reticulatus) get. The two species vie for the title of world’s largest snake: the anaconda is unquestionably heavier bodied than the slimmer reticulated python; but which gets longer? I’ve compiled a few judgments from the respectable literature immediately available to me.

Author Anaconda Reticulated Python
Barbour, 1926 14 m 32 ft. (29 ft. personally)
Ditmars, 1931 25 ft. (19 ft. personally) 33 ft. (24 ft. personally)
Ditmars & Crandall, 1947 26 ft. 33 ft.
Pope, 1955 30 ft. 32 ft.
Bridges, 1966 26 ft. (Bronx Zoo, ca. 1899)
Minton & Minton, 1973 38 ft. (Rondon; Lamon) 33 ft.
Ernst & Zug, 1996 11.5 m (Lamon) 10.1 m
Greene, 1997 10 m 10 m
Santora, 2002 26 ft. (Bronx Zoo, 2002)
Attenborough, 2008 7.5+ m 10 m
Pough et al., 2008 9 m
Vitt & Caldwell, 2009 8m, possibly 11.5 m 10 m

You can see that the authorities disagree, with reticulated pythons being generally credited with a length of 32-33 feet (= 10 m; the Bronx Zoo lengths are of specific animals, not the largest ever), while anacondas are either 30 feet (or less) or 11.5 m. Now there are several problems with knowing the maximum size of a species of large snake, beginning with the fact that the biggest snakes will probably be rare. But once you find one, how do you measure it? It is very hard to measure a live snake– I know from experience. They won’t sit still, keep curving, and might bite you. Now make its length more than 4 times your height! But if you collect the snake, the only practical way of preserving the specimen is as a skin, and skins notoriously stretch. A few cases of comparing the size of the snake and its skin have been reported, and the skin is about 20% longer than the snake.

Generally, claims about the size of animals are based on actual museum specimens, but for giant snakes these are only skins, which are unreliable due to stretching. If measured in the field and not collected, then it is the credibility of the informant that determines whether a record is accepted, since there is no specimen. The maximum size of the anaconda is generally seen to hinge on whether or not we accept the record of Robert Lamon, a petroleum geologist said to have measured one in Colombia that was 11.5 m long, and which was published by Emmet Reid Dunn in 1944, an eminent American herpetologist resident in Colombia at that time:

Mi amigo el señor Robert Lamon, geologo de la Richmond Oil Company, me ha dicho que mato y medio un ejemplar de once metros y medio en los Llanos. Tambien he oido hablar de ejemplares de 14 metros pero la aseveracion del señor Lamon no es de “segunda mano” sino directa y digna de credito. (Translation by GCM: “My friend Mr. Robert Lamon, geologist for the Richmond Oil Company, has told me of killing and measuring a specimen of eleven and a half meters in the Llanos. I have also heard talk of specimens of 14 meters, but the firm declaration of Mr. Lamon is not ‘second hand’, but first hand, and deserves to be accepted.”

A number of herpetologists have further investigated this case, most notably John Murphy and the late Robert Gilmore (the latter actually a mammalogist). Gilmore met Lamon, and corresponded with him in 1954, but Lamon could not recall what his measurement had been. He did attest that he told Dunn about it at the time, so that whatever Dunn had written down would be most reliable. He added the interesting detail that he measured the snake with a 4 m rod (not a steel tape, as some had added to the story). Later, in 1977, Gilmore met some other Colombian petroleum veterans, who cast some aspersions on Lamon’s credibility, but these aspersions must themselves have their credibility contested, being decades old recollections, not contemporary accounts. Gilmore and Murphy (1993) conclude that skepticism is warranted, and Murphy and Henderson (1997:45) explicitly say the measurement is “Probably in error”. We should always, of course, think it possible we may be mistaken, but I lean the other way, and my acceptance of the Lamon record is stronger now than it was yesterday, having investigated, probably as thoroughly as is still possible, the circumstances involved.

Sherman and Madge Minton (1973), besides Lamon’s anaconda, mention some other ca. 38 foot records of anacondas, records that have not been as thoroughly documented or investigated. One of them is attributed to Candido Rondon, the great Brazilian explorer and military officer, after whom the state of Rondonia is named, and who was the co-leader of Theodore Roosevelt’s last expedition (“The River of Doubt“). This seems, to me, to be a record worth pursuing– there is a likelihood that there may be substantial documentation concerning Rondon’s expeditions, as they were official expeditions undertaken as part of his military duties.

The Bronx Zoo for many years offered a reward for any snake 30 feet or more in length. Here is how late Curator of Reptiles John Behler put it in 1997:

The New York Zoological Society (i.e., the Wildlife Conservation Society) has offered a large reward for the live delivery of a 30-foot snake, in good health, to the Bronx Zoo since the days of President Teddy Roosevelt (1910). The reward offer currently stands at $50,000. Although there have been many inquiries and requests to finance giant snake expeditions (which we do not support), there have been no giant snakes presented for the reward.

The offer was terminated in 2002, when Samantha, the Zoo’s 26 foot long reticulated python died. (Further notes about her, including her capture, have been provided by a former keeper.)

Samantha the reticulated python at the Bronx Zoo. That’s John Behler on the far left. From the BBC, but a larger b&w version is in the NY Times notice of Samantha’s death.

Reticulated pythons regularly get longer than anacondas, as captive retics in the 25-29 foot range are not uncommonly reported, but I’ve not carefully investigated such claims. Guinness World Records lists a captive record of 25 feet 2 inches, but this is smaller than Samantha. Samantha’s last measurement was probably after her death, so would be a reliable measurement. The Guinness snake, named Medusa, was alive when measured, so might actually be longer, as it is hard to get the “kinks” out of a large snake for measuring, and these would make the measurement come out shorter than in a relaxed snake.

Medusa, Guinness’s record reticulated python. It is not in a zoo; I’m not sure what this place is.

Although wild anacondas are heavier bodied than pythons (and retics are especially slim), I’ve seen captive Indian/Burmese pythons which are long (in the teens of feet) and extremely obese, and which might well weigh more than anacondas of the same length.

Attenborough, D. 2008. Life in Cold Blood. Princeton University Press, Princeton, N.J.

Barbour, T. 1926. Reptiles and Amphibians: Their Habits and Adaptations. Houghton Mifflin, Boston.

Bridges, W. 1974. Gathering of Animals. Harper & Row, New York.

Ditmars, R. 1931. Snakes of the World. Macmillan, New York.

Ditmars, R.L. and L.S. Crandall. 1947. Guide to the New York Zoological Park. 5th, “Platypus”, ed. New York Zoological Society, New York.

Dunn, E. R. 1944. Los generos de anfibios y reptiles de Colombia, III. Tercera parte: Reptiles; orden de las serpientes. Caldasia 3:155-224.

Ernst, C.H. & G.R. Zug. 1996. Snakes in Question. Smithsonian Institution Press, Washington, DC.

Gilmore, R.M. and J.C. Murphy. 1993. On large anacondas, Eunectes murinus (Serpentes: Boidae), with special reference to the Dunn-Lamon record. Bulletin of the Chicago Herpetological Society 28:185-188.  pdf (Provides a good summary of the earlier literature, including important works which, because I did not have copies to hand, are not cited here.)

Greene, H.W. 1997. Snakes: The Evolution of Mystery in Nature. University of California Press, Berkeley

Heuvelmans, B. 1959. On the Track of Unknown Animals. Hill and Wang, New York.

Minton, S.A. & M.R. Minton. 1973. Giant Reptiles. Scribner’s, New York.

Murphy, J.C. and R.W. Henderson. 1997. Tales of Giant Snakes: A Historical Natural History of Anacondas and Pythons. Krieger, Malabar, Florida. full text

Pope, C.H. 1955. Reptiles of the World. Knopf, New York.

Santora, M. 2002. Never leather, Samantha the python dies at the Zoo. The New York Times, 22 November 2002, p. B3.

64 thoughts on “A 15-meter anaconda?

    1. The address of the venue places it in the west side, in fact the west Edge of K.C., Mo. The kind folks supporting the snake look too happy to be from Westboro Baptist, but I could be mistaken..

    2. The folks in the picture supporting Medusa at The Edge of Hell all somehow appear to be PORGs (people of restricted growth), although I might be mistaken. Even if so, still a giant snake.
      I have some acquaintance with reticulated pythons of about 6m, and slightly shorter anaconda’s, the anacondas were more bulky though.
      As our host points out, it is difficult to assess the real length of the anaconda in the video. I would not be surprised an anaconda -or reticulated python for that matter- could actually reach a 15m length. These snakes keep growing until death.

      1. These snakes keep growing until death.

        That was a question I had too. I’ve heard that assertion for various non-mammalian amniotes (“reptile” is paraphyletic, including many spineless anthropoid politicians and more complex cases) but I’m less sure of it’s truth. One would expect the zoo-keeping world to be able to answer the question “yes”, “no”, or “yes, for these, no for those and undecided for the rest”. Not my knowledge base, but it should be there.
        Another point occurred to me : humans vary in spine length by several centimetres through the day. Does the same apply to snakes over (for example) whether they’ve been actively travelling, or coiled for ambush for several hours?

        1. Well I’m not aware of any report these snakes stop growing -unless dying, of course. But I agree that it has not been firmly established. I haven’t a clue about python and anaconda life spans, only that it spans decades.
          The same is said about male African elephants, and they can become huge indeed. However, their lifespan is limited to about 50-60 years due to the loss of molars (IIRC they have only 3 replacements).
          Talking about African elephants: in the Congo Museum near Brussels I saw a pair of tusks nearly 3m long, and thicker than your leg. Those are not found anymore. Probably due to hunting and poaching. The big tuskers were selected against, it seems.

          1. Yes, big tuskers have faced several generations of strong selection pressure against them. But I recently saw something describing a “super tusker” as an elephant whose tusks could touch the ground, and that there are only about 50-such in the world. Human predation is a problem, of course, but in the wild tusks do get broken which would also limit maximal tusk size. But the genes are still in the population.

  1. Thank you for the wonderful snake story! I love big snakes but would never have one.

    When there’s an awful incident in which a big pet snake injures or kills the owner, the human is to blame. We herpers speak of “SFE’s”, or “stupid feeding errors”.

    Thanks for posting the pictures! I’ll look at big snakes in pictures or zoos, and look at small snakes right in my own house.

    1. Yes, these giant constrictor snakes can be dangerous. I’d never approach one alone.
      Their hunting technique is a head-butt+bite stunning the victim, and quickly coil around. Once coiled you will have difficulty escaping without some outside help to uncoil.

      1. You speak of large constrictors snaring their prey by “a head-butt+bite stunning the victim…” In the Hili Dialog on Feb. 22, there’s a video of some sort of constrictor(can’t tell how large, but it ain’t so small) dangling from something out of sight, and hauling up a bird by its head. As it rises back to its perch, it begins to coil around the bird in mid-air. It’s rather amazing to watch but I find it unsettling, even though I love snakes https://twitter.com/ZonePhysics/status/1098631846005534720.

        You’re a regular reader of WEIT, you must have seen this, but I find no comments by you on that post; perhaps you missed that day. I was curious as to how the snake got the bird, since it was raised by its head, and the actual constricting didn’t begin until the snake was on the upswing, but I think your explanation solves my quandary.

        1. I must have missed that post. But indeed, they do target heads with their head-butt+bite. They are stunning their prey and heads are obviously the best target for that.
          I -well my young son- do(es) have a ball python (because ball pythons do not grow very large and have an agreeable, if not docile disposition, they never bite and even appear to enjoy being handled) and when a mouse is fed it always hits the head.

  2. I will believe the sucuri (Brazilian Portuguese for “anaconda”) in the video is 15m long when I see the guys holding it down against a tape measure. The snake had its dorsal half well out the water because it was slithering across shallow mud. The video and narration seem authentic.

    1. … in microscopic lettering, in either Hebrew or cuneiform script, on the underside of a scale. Somewhere. As the documentary “Blade Runner” showed.

        1. “Wake up! Time to die!”
          I don’t get many chances to say it, but I savour them when I do.

    2. Nope, there is no mention of it being a particularly big snake, it doesn’t even mention whether it is a constrictor or a venomous one, the story is vague on details. It is one that could talk though, so probably not one of the extant species, which are anatomically incapable of speech.
      And the fruit was from the tree of wisdom, why would that be an apple and not, say, a banana? Or a Durian?
      If taken literally it is a shitty story, and even as metaphore I find it weak.

  3. You want to measure the length of a live snake? Take it to a motion capture studio an put some reflective dots on it. Between the images from many angles and the dots you can reconstruct a pretty good 3-d model of the flesh-tubes with backbone.

    1. How about a 3-D laser mapping unit like the ones used by archeologists to map ruins without physical interference? Given a 3-d computer model that includes the snake, I’m sure an algorithm could be designed to estimate its length.

      1. “just hold the snake”
        – no, you hold it! 🙂

        I wouldn’t want the job of applying motion capture dots to it, either.


    1. Not an expert, but I think they have indeterminate growth which means they don’t stop growing. I expect that different species grow at different rates, however.
      What limits their size would be physics. For one thing they do not have a strongly protective rib cage so their weight would inhibit breathing if they got too large. This restriction would be set back if they were aquatic.

      1. I think that is the reason anacondas are predominantly aquatic indeed, especially the large ones. On land they appear very vulnerable, if not outright out of breath.

      2. For one thing they do not have a strongly protective rib cage so their weight would inhibit breathing if they got too large.

        In another context – eating things bigger than your head – that got discussed recently, though I didn’t note where – some science Q+A program I think.
        Consider a snake ingesting something that needs that jazzy mandible-walking technique which snakes have. It has got to slither down an oesophagus quite a distance to the stomach, past the trachea and lungs. (Lung? Aren’t some snakes wildly asymmetrical in the lung department?) That can take some time – hours. So … there has got to be some mechanism that allows a routine operation like eating to proceed without suffocating the beast.
        We’re getting into “spherical bumble-bees can’t glide” territory here. There must be some mechanism, but what it is, I’ve no idea.

        1. These snakes, all snakes, have jaws that can disarticulate top from bottom and left from right. They can also separately move their windpipe. After swallowing, the passage from oesophagus to stomach is relatively fast, say a minute or two, or so. A poikilotherm can go easily without breathing a minute, or even a minute or ten. It works pretty well. Never heard about a snake choking on it’s prey.

          1. All snakes have that property? Actually, several properties – multiple articulations between several bones of the jaw and several bones of the skull. … I need to go check a paper.

            1. My memory was mis-playing. A paper I read a while ago (“The origin of snake feeding” Michael S. Y. Lee, Gorden L. Bell Jr & Michael W. Caldwell Nature volume 400, pages 655–659 (12 August 1999) had talked about the flexibility of snake jaws and jaw-skull attachments, and showed that Mosasaurs had an intermediate stage between that set of characters and the more rigid arrangement in lizards. I’d mis-remembered that as being observed variations within the snake lineage, not as showing the relations of lizards, mosasaurs and snakes.
              If you get past the “naming of parts”, the palaeontology of the skulls of terrestrial tetrapods (and several occasional secondarily aquatic tetrapods) brings dreams of bones sliding around all over the skull, cartilages forming and unforming at whim, tooth-bearing oral structures changing in number … I could almost forgive a Creationist for holding their skull in their anterior distal limb structures unable to keep track of what is where and where it used to be. Almost.

    2. The bigger a snake gets, the more friction it generates as it rubs along the ground. This has to be a limiting factor, although I can’t recall ever seeing a formal treatment of it.
      Titanoboa (from the Eocene of South America is estimated to have reached 12.8 m total length, but it seems to have been an aquatic piscivore.

      1. I watched a video of a long & heavy anaconda struggling to cross a tarmacked road, but I very much doubt that is a limiting factor in its normal semi-aquatic environment. Anacondas are known to continue to grow throughout their lives & the females produce larger clutch sizes in line with their own size up to some hard limit to clutch size. [from Wiki].

        Lars – is there a limit to girth? Is a snake born with x number of ribs for life or do they add on like a Meccano? 🙂

        1. Rib number is fixed at birth, I believe – it is for most tetrapods. However you can get some variation in rib number (not an outlandish amount) among individuals within a species. We did a study on lizard vertebral number a couple of years ago and had to throw a number of specimens out because their vertebral number varied; we had to settle on a mode and only use lizards that matched the mode (for our multivariate analysis – something like vertebral number couldn’t be allowed to vary).

          1. TYVM – interesting that birth vertebrae number can vary among some species. That in itself is a study I guess.

        2. Answering for Lars, who has succumbed to a severe case of inadvertent aliasitis.
          I don’t believe that rib number generally varies from birth in tetrapods – it’s determined by the number of somites, which in turn is under control of some early-acting developmental genes.

    1. The original is much clearer and shows a flooded country road; judging by the wheel ruts, I guess the snake is less than three car widths.

    2. Oh, well spotted.

      I don’t think the video has been ‘stretched’ so much as, the aspect ratio has been changed. The net effect is the same, though.

      That’d also be why the snake looks so fat later in the video when we’re looking along its length from behind.


      1. I don’t think the video has been ‘stretched’ so much as, the aspect ratio has been changed. The net effect is the same, though.

        Ah right. Just now downloaded both vids and messed with them in MPC-HC. Simply switching the original video (0.550 aspect ratio) to 16:9 aspect ratio looks like it does the trick.

    1. I think you can also very roughly estimate size by noticing the grass as the snake crawls through it. I agree that it’s much smaller than advertised.

    2. Incidentally the ‘before’ video was stretched x 3.2 horizontally to get the ‘after’ fake longer snake.
      The ‘after’ hassn’t been cropped at all
      See comparison pic below.

      Image ‘before’ = 405 x 720
      Image ‘after’ = 1280 x 704 [bars top & bottom]


        1. I think it was the other Geldoff, Fifi Trixibelle, I keep getting her mixed up with Moon Unit Zappa though.

            1. The registrar wouldn’t permit that birth name – his given name is vanilla insurance salesman boring [not literally y’all], but everyone called him Dweezil anyway. He changed it to Dweezil by deed poll later.

              Not a happy bunch the extended Zappa clan – money fights over a trust that’s in debt. Hollywood shit. It’s good to be a Norm!

              Moon’s daughter is called Mathilda Plum Doucette – almost nice, but almost hygiene product IMO 🙂

  4. I notice that Major Percy Fawcett’s immediate reaction on encountering the biggest anaconda in the world, was to try and shoot the poor thing.

    What a surprise.


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