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.

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.

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.)

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.

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.

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.