Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
There was also a discussion of the stretched video on reddit. The snake now looks like a typical anaconda: the stretched one made its color pattern look a bit odd, and appear to be very wide (which added to the impression of great size). After watching the original video, I sent the following message to Jerry:
It’s not fake, but it’s been stretched from a vertical cell phone video to fit a 16:9 format. I’ve now seen the original video. It’s crossing a road (not a stream), it’s not swimming, the guy filming is walking (not in a boat). It’s a big snake, but on the order of 5-7 m, not 15. Readers found this, and I’ll put it together into a post for tomorrow afternoon.
My guess on the conversion ratio was right, or close to it (see the detailed discussion by Michael Fisher and Roger on figuring out the exact method of aspect ratio conversion/stretching). The video was posted by the Youtube account of Dumato, a Swiss company with Brazilian roots. They said this about it in the video description:
Many thanks to Dinda from Manaus who took this video and sent to DUMATO, showing how Amazonia is alive and free
davelenny, judging by the ruts in the road, figured the snake to be less than 3 car widths long (which would be less than 18 ft. for a 6 ft. wide vehicle such as a Jeep or Land Rover. Michael Fisher, noting that the ruts are likely to be 60 inches apart, so that the road would have a width of 10 ft., suggests a total length of 12-15 ft. (ca. 4-5 m) for the snake. Jeeps/trucks have wider axles (65″ for a Toyota Land Cruiser), and the flooded section of the road where the snake is is a bit wider than the rest of the road, so I’d go a bit larger than Michael. My initial guess of 5-7 m is probably not way off, but I would lean more toward the lower end of that range.
Next, there’s the size of the anaconda on display at the San Diego Natural History Museum. It is about 22 feet, which I figured out by measuring the floor tile length using my feet (my feet, shod, are one foot long, as I’ve verified on many floor tiles and soccer fields), and then counting the number of floor tiles from one end of the snake to the other.
Anaconda on display at the San Diego Natural History Museum.
My hat, which placed in the picture for scale, is 7-8 inches across. Michael Fisher, using the hat, came up with 20 feet, which was the closest of any reader, and given the angle, a pretty good estimate. So, with a 20% stretch, the live length would be 18.3 feet, which is spuriously precise, so let’s say 18 feet.
Shed skin of ball python (Python regius), ca. 1.2 m total length.
Note that the shed skin is translucent and nearly patternless; it is also much lighter (in weight) than an actual skin, which is what is on display in San Diego. Shed skins are only rarely taken as specimens for museums, usually only to document very uncommon species or occurrences. The above is a shed from my ball python, Vyvyan. Below, you can see the skin between the scales. The scales are nearly transparent, but the skin between is more opaque; it is this opaque skin that gives a skin its “stretch”.
Shed skin of ball python (Python regius), ca. 1.2 m total length.
The anaconda in the video posted this morning is real, but it is certainly not 15 m long. Alert readers went digging, and found clues (posted in the comments) as to what the story is. I’ll post on that later, but for now, here’s another anaconda, this one a specimen I saw on display at the San Diego Natural History Museum. How big do you think it is?
Anaconda on display at the San Diego Natural History Museum, 16 January 2019.
This illustrates at least two phenomena, both of which have been problems in determining how big giant snakes can get: the difficulty of estimating size, and the effects of skin stretching. I’ll post my measurement of this snake along with the reveal on the “15 m” one later.
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 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.
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.
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.
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.
