Anyone who's anyone has heard of the Anaconda. But in fact 'the' Anaconda is the Green anaconda Eunectes murinus. Most zoologically-informed people know that there's a lesser-known, smaller relative of this large species, namely the Yellow or Paraguayan anaconda E. notaeus. Usually only reaching 3-4 m in length (as opposed to 5-9 m for the Green anaconda), the Yellow anaconda [photo here by Dave Hone] typically has a yellowish ground colour, and black spots, patches and streaks decorate its length.
Far less well known is that there are actually a few other anacondas as well. The Dark-spotted or de Schauensee's anaconda E. deschauenseei (wow, vowels) was originally described from Marajo Island in the mouth of the Amazon (Dunn & Conant 1936). Its status as a valid species has sometimes been questioned, but recent work supports its distinction, and it seems closely related to the Yellow anaconda (Dirksen & Böhme 2005). This is interesting, as the two are widely separated (by about 1000 km). It's therefore been suggested that their current distributions are relictual, reflecting the former fragmentation of the Amazonian forest by extensive savannahs (O'Shea cited in Shuker 2002). However, whether Amazonia ever was fragmented by savannah habitat is a controversial subject - in fact some of the literature on this area concerns the distribution of grassland-dwelling snakes, and I've been promising to cover this subject since 2006 [Dark-spotted anaconda below from wikipedia. UPDATE (added Sept' 2010): apparently the photo does not depict a Dark-spotted anaconda at all, see comment 30].
Even less well known is that a fourth species is currently recognised: E. beniensis Dirksen, 2002 from Beni Province, Bolivia. Originally identified as the result of hybridisation between Green and Yellow anacondas, E. beniensis was shown to be distinct by Dirksen & Böhme (2002), and as the sister-taxon to the E. deschauenseei + E. notaeus clade. It has a brownish ground colour, possesses five stripes on its head, and is patterned with dark, solid blotches. A few other anaconda species have been named over the years (including E. scytale Stull, 1935 and E. barbouri Dunn & Conant, 1936), but none are currently regarded as valid.
All anacondas are semi-aquatic boas with small, dorsally positioned eyes and relatively narrow heads. They predominantly rely on ambush, catching and eating amphibious and aquatic reptiles, mammals and birds as well as fish. Large individuals sometimes eat large caiman and mammals as big as capybaras and tapirs. A young Yellow anaconda specimen had swallowed Limpkin eggs (the Limpkin Aramus guarauna is a rail-like wading bird of the American tropics) [another captive Yellow anaconda below. I had to crop the image strangely thanks to the flash on the glass].
A brief diversion on snake phylogeny that many of you will find boring and may well not want to read
Phylogenetic work shows that anacondas are part of a New World boa clade that also includes Boa constrictor (the only snake commonly referred to by its scientific name: its 'real' common name is Common boa), Corallus (the tropical American tree boas) and Epicrates (the Greater Antillean or rainbow boas). Eunectes seems to be the sister taxon to Epicrates, though Burbrink (2005) found that Epicrates cenchria - the Rainbow boa - was the sister-taxon to the Eunectes + 'rest of Epicrates' clade. If this is right, it means that all those other Greater Antillean boas currently included in Epicrates will need a new generic name, as E. cenchria is the type species for the genus Epicrates Wagler, 1830. Several names are available; I think the oldest is Chilabothrus Duméril & Bibron, 1844 (but I can't find out what the type species of Chilabothrus is).
Incidentally, B. constrictor has always been a bit of a weird taxon from a phylogenetic perspective, as several studies (most notably Kluge 1991) have found it to be more closely related to the Madagascan boas Acrantophis and Sanzinia than to other Neotropical taxa (Kluge (1991) actually regarded all three taxa as congeneric). Needless to say, this inferred relationship (which recalls the distribution of certain iguanian lizard clades) resulted in various different biogeographical scenarios. However, Vences et al. (2001) and Burbrink (2005) later found B. constrictor to be the most basal member of a New World boine clade that also includes Corallus, Eunectes and Epicrates [Common boa below from wikipedia].
Boas - the seven genera grouped together as Boinae - have traditionally been allied with the sand boas and rubber boas (Erycinae) in a group called Boidae. Several other groups, including the bolyeriines (Round Island boas), tropidophiines (or tropidopheines, the Caribbean dwarf boas or wood snakes), ungaliophiines (or ungaliopheines, the Neotropical banana boas or Neotropical dwarf boas) and pythonines (pythons) have also been included within Boidae 'traditionally'. Or, at least, this is the impression I always got from the popular literature: in the technical literature, a lot of work has shown that some of these 'boa-like' snakes are not really so boa-like (e.g., McDowell 1979, Kluge 1991) [the bolyeriine Casarea dussumieri shown below, from wikipedia].
While it is widely agreed that all boa-like snakes are basal to Caenophidia (the acrochordid + colubroid clade), it remains controversial whether all boa- and python-like snakes form a clade (the correct name for which is probably Booidea*), or whether they form a series of outgroups to Caenophidia. Lee & Scanlon (2002) found boines, pythonines and erycines to form a clade (Booidea), while ungaliophiines, tropidophiines and bolyeriines were basal members of an 'Advanced snake' clade that also included Caenophidia. Vidal & Hedges (2002), employing data from nuclear and mitochondrial genes, also found tropidophiines and bolyeriines to be closer to Caenophidia than to boines, pythonines and erycines. They later found tropidophiines to group with Anilius, the South American pipe snake, in a position more basal than the boa-python + Caenophidia clade, and they also recovered some other weirdness: uropeltids (shield-tailed snakes) were up close to caenophidians, for example, and xenopeltids (sunbeam snakes) and Loxocemus (the Mexican burrowing snake) were found to be part of the boine-pythonine-erycine clade (Vidal & Hedges 2002). At the risk of elaborating further, I'll stop there. You may note that many details of snake phylogeny are contentious, and that the potential for a lot of interesting research remains. Dammit, so much for a text-lite 'picture of the day' post... DAMMIT!
* Does anyone know of any literature that provides phylogenetic definitions for snake clades? I have yet to see any.
PS - if you've come here hoping to read about the new, sauropod-mimicking dacentrurine stegosaur Miragaia, please take my advice and go here instead.
Refs - -
Burbrink, F. T. 2005. Inferring the phylogenetic position of Boa constrictor. Molecular Phylogenetics and Evolution 34, 167-180.
Dirksen, L. & Böhme, W. 2005. Studies on anacondas III. A reappraisal of Eunectes beniensis Dirksen, 2002, from Bolivia, and a key to the species of the genus Eunectes Wagler, 1830 (Serpentes: Boidae). Russian Journal of Herpetology 12, 223-229.
Dunn, E. R. & Conant, R. 1936. Notes on anacondas, with descriptions of two new species. Proceedings of the Academy of Natural Science, Philadelphia 88, 503-506.
Kluge, A. G. 1991. Boine snake phylogeny and research cycles. Miscellaneous Publications, Museum of Zoology, University of Michigan 178, 1-58.
Lee, M. S. Y. & Scanlon, J. D. 2002. Snake phylogeny based on osteology, soft anatomy and ecology. Biological Reviews 77, 333-401.
McDowell, S. B. 1987. Systematics. In Seigel, R. A., Collins, J. T. & Novak, S. S. (eds) Snakes: Ecology & Evolutionary Biology. Macmillan (New York), pp. 3-49.
Shuker, K. P. N. 2002. The New Zoo. House of Stratus, Thirsk, North Yorkshire.
Vences, M., Glaw, F., Kosuch, J., Böhme, W. & Veith, M. 2001. Phylogeny of South American and Malagasy boine snakes: molecular evidence for the validity of Sanzinia and Acrantophis and biogeographic implications. Copeia 2001, 1151-1154.
Vidal N, & Hedges SB (2002). Higher-level relationships of snakes inferred from four nuclear and mitochondrial genes. Comptes rendus biologies, 325 (9), 977-85 PMID: 12487103
- . & Hedges, S. B. 2004. Molecular evidence for a terrestrial origin of snakes. Proceedings of the Royal Society of London B (Suppl.) 271, S226-S229.
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What do those figures exactly mean? A dissertation by Jesús Antonio Rivas found no males longer than 3.39 m or females longer than 5.21 m in a pool of 780 individuals. Unless there is a considerable amount of geographical size variation, is 5 m the "normal" maximum for E. murinus? It would seem hard to believe that other individuals of the same species can reach lengths 1.8 times (and presumably weights ~6 times) greater than already large individuals.
Oh, and the Guinness Book of Animal Facts & Feats cites a source which claims that E. notaeus "does not exceed 7m" - something I can definitely believe!
Well, good point Cameron: by referring to '5-9 m', I meant that the 'upper length limit' of this species falls within this range. In other words, a very big Green anaconda is almost always much bigger than a very big Yellow anaconda. Green anacondas longer than 5 m may indeed be rare, but there are several apparently reliable reports of specimens over 9 m long, and I'm not talking about Percy Fawcett-style stories. See the comment here.
That's funny, I thought there were thousands of anacondas. ;)
Seriously, though, isn't it weird that some taxonomic names (primarily genera and species) are singular while others are plural? Really, shouldn't they all be plural? As it stands, talking about species sounds oddly like talking about archetypal characters in a myth or a Just-So Story: The Anaconda, The Boa, The Hare, The Raven, The Human, etc. (It also sounds kind of like a certain verbal tactic often employed in racist speech: The Jew, The African, The White Man, etc.)
I'm not saying anything needs to be done about it; I just think it's a funny quirk.
On another note, doesn't murinus mean "mouselike"? That can't be right....
Hi! I've read your blog a few times and really enjoy it, but this is my first time commenting. Great article! I'm fascinated by snakes and have been considering finally going to university to take up biology to eventually pursue research involving snakes.
Something you said definitely gave me hope:
'You may note that many details of snake phylogeny are contentious, and that the potential for a lot of interesting research remains.'
My question is how does one start doing phylogenetic work? Do you just start with a basic biology degree, or should I be looking for courses that are specific to reptiles, or specific to phylogeny even?
Thanks!
It took me embarrassingly long to realize that "boid" is pronounced "bo-id" and not as if Bugs Bunny were saying "bird".
p.s. Watch out, I just found out that pixelsnake would wipe the floor with you, in Mortal Kombat.
"Several names are available; I think the oldest is Chilabothrus Duméril & Bibron, 1844 (but I can't find out what the type species of Chilabothrus is)."
It seems that Duméril & Bibron (1844) first used that genus as a new combination for Boa inornatus Reinhardt, 1843; therefore it is possible that the type species of Chilabothrus is Epicrates inornatus (Reinhardt, 1843). Unfortunately without actually looking at Duméril & Bibron (1844) I might just be speculating.
Pixelsnake: hopefully you will get some excellent advice from certain Tet Zoo regulars, I will hold off commenting for now as someone else will be able to do a better job. Thanks for the kind comments.
Nathan: on pronunciation of 'boid the snake' vs 'boid' as pronounced by Bugs Bunny, a palaeontologist friend of mine one wrote a whole email on 'Cretaceous boids'. I naturally assumed that he was referring to the discovery of Mesozoic python-like snakes, at least until he started talking about enantiornithines and all became clear. How we laughed! :)
Pixelsnake, What you need is a basic biology degree to give you the background in biology and cognate fields (chemistry, physics, math, etc.) which you need. Are you familiar with the various professional societies: American Society of Ichthyologists and Herpetologists, Society for the Study of Reptiles and Amphibians, Herpetologists' League, etc. for example? Most of these organizations have student memberships. Look at the journals they publish and the abstracts for the annual meetings. This will get you into who is doing what where. Figure out the kind of college/university you want to attend and then find one with a herpetologist who teaches a course in herpetology available to undergraduates.
Yep, a long silent pet peeve of mine.
Well, it could be a lame joke, like Balaenoptera musculus, the blue whale, which is a little mouse by name.
Thanks Jim! I admit that the whole university system is still a little confusing to me, so it's nice to just get pointed in the right direction. Also, I live in a small, rural area of Nova Scotia, and not many people are interested in science here so the intertubes are my only guide.
How detailed phylogentic definitions are you looking for? IE, character based? There's a pretty good snake phylogeny over in Pough et al:
Pough FH, Andrews RM, Cadle JE, Crump ML, Savitzky AH, Wells KD. Herpetology, third edition. Pearson Prentice Hall. 2004. ISBN 0-13-100849-8, pp147-166.
If you're just looking for an outright phylogeny, I also have a compiled phylogeny at a site I'm helping the UCMP with, after Phylogeny after Benton, 2005; Pough et al 2004; Flynn et al 1998; Arnason et al 2002; Feldhamer et al. 2007; Gatesy et al 2001; Szalay et al 1993; Roca et al 2004; Matthee et al. 2001; Milinkovitch et al 1994; Wiens et al 2008; and the Tree of Life.
Thanks for the link tigerhawkvok (if that is your real name), but I'm not looking for a phylogeny, but rather for a set of phylogenetic definitions: viz, 'Booidea is a branch-based clade consisting of all taxa closer to Boa constrictor than to Natrix natrix' etc. etc.
I'd never heard of these species; thanks!
Where does Titanoboa fit into these questions aboit booid phylogeny?
Ah, yeah, I've not seen any of those. The Pough et al. text has definitions as "Loss of levator anguli oris muscle; supraorbital bone present" with citations. I suppose that's a apomorphy-based clade, whereas you're looking for stem-based. I suspect that's because of the horrid state of Colubridae; its so frighteningly paraphyletic that the best anyone can really do is give stem-based (branch-based) definitions for non-colubroids. One of the papers I cited earlier resolved most of the polytomies in Serpentes, at least. I'm not sure what makes a better branch-based definition than any other, though, assuming you have sufficient resolution; shouldn't a definition like "Boidae is comprised of all taxa closer to Boa constrictor than to Xenophidion acanthognaus" be as good as any other?
At any rate, under Boidae, they cite:
Kluge (1991, 1993a,b), McDowell (1979), Rieppel (1977,1978), Underwood (1976), Underwood and Stimson (1990), Vences et al. (2001), Wilcox et al. (2002).
Perhaps those will shed some light.
Yeah, I've not decided how to do the posting here. In Pharyngula I set up a TypeKey showing my real name, and considering I link to my site with my real name all the time, seems a bit silly, but eh. I like my handle, been using it for 10 years now. *Shrugs*.
@ William: Titanoboa is a full-on boine, based on vertebral character combinations.
We did a little bit of clade-defining in:
Lee, M.S.Y., A.F. Hugall, R. Lawson, and J.D. Scanlon. 2007. Snake phylogeny: Combining morphological and molecular data in parsimony and likelihood analyses. Systematics & Biodiversity 5: 371-389.
However, there's so much conflict in the data that we only gave definitions for a few completely stable clades (Scolecophidia, Alethinophidia, Caenophidia). There probably is no Booidea in the Kluge 1991 sense, the molecular data points to boines and erycines being tangled up with ungaliophiines, pythons further stemward (with Xenopeltis/Loxocemus as basal pythons), and tropidophioids leaping about anywhere between Anilius (basal Alethinophidia) and Acrochordus (basal Caenophidia).
(The paper didn't make much of splash as it got held up so long by reviewers that a bunch of other data-combining approaches were published first. Ho hum.)
So anyway, Booidea is up for grabs. The definition Darren suggested would probably gather in erycines, Calabaria, ungaliophiines, and might or might not include tropidophiines. Probably not pythons or bolyeriids.
Mike K. and David M.--
You're both being a little over-fastidious in your linguistic tastes! The construction "definite article + singular noun" is one of the standard forms for the subject of a generic sentence. It isn't restricted to biological or anthropological categories: "The regular pentagon has angles of 108 degrees." (Did you notice the "the" at the beginning of the sentence before last?) ... Phrases like this are called "distributive singular terms" in at least some of the philosophical and linguistic literature (where explaining the semantics of generics is regarded as one of the HARD problems). Treating them as if they were genuine singulars is a source of wordplay (e.g. Darren's second sentence), but arguably also a source of inspiration for philosophical theories like Plato's.
English, b.t.w., idiosyncratically drops the "the" before a few nouns: "Man is bipedal" would be translated with a definite article in many languages (e.g. French: "L'homme est bipède").
Not even -- it's a diagnosis. It's not a definition in the first place.
An apomorphy-based definition would be like "the first organism to have a supraorbital bone homologous to that in the type specimen of Boa constrictor, plus all its descendants".
BTW⦠loss of that muscle means they can't smile anymore. :-|
Yes. We're wondering about why that is, because it's <Vulcan mode>not logical</Vulcan mode>.
Even German. The articles of English and German are homoiologous. :o)
I can't find an online definition of "homoiologous", but from David's example I guess it means "deriving from the same ancestral structure but not homologuous in their present functions"? Would bird and bat wings, qua wings, be homoiologuous?
Allen, fair enough, but then why do we use this construct for some taxa and not others? Find me a scientific text that says, "The mammal produces milk," in reference to all mammals.
I would say that the idea of archetypes is probably already present, hardwired into our brains, as a generally useful tool for making generalizations, and that its use in language, biology, and Platonism might all be independently derived from that basic hardwiring (although not necessarily -- was Plato actually inspired directly by grammar?). But now we've gotten very far away from the topic of anacondas....
Incidentally, although I said taxa probably should all be plural, they could just as easily all be singular. (In fact, in a way that makes more sense, since a taxon is a single object, a set.) What really bothers me is the inconsistency. Why do we speak of The Green Anaconda, but not The Chordate or The Bilaterian? Why does, "Psittacosaurus is an early ceratopsian," sound fine, but, "Psittacosauridae is an early ceratopsian," sound wrong?
Exactly: they're homologous as forelimbs, but analogous as wings.
The term is very rarely used.
Ouch, ouch, ouch. Here we get into Sapir-Whorf-hypothesis territory... Duck and cover!
Well, for me, I can give a very simple answer: I know Latin, so I know a singular and a plural ending when I see it.
We can also do it backwards: Linnaeus derived his concepts of "genus" and "species" from Aristotelian philosophy, and that's why both were singular to him, as well as why the higher taxa were plural.
<sigh> Why don't we just have this whole discussion in Chinese, where singular vs plural is almost only marked on personal pronouns... ;-|
I have often envied Chinese speakers for exactly that reason.
I have also often wished that the concept of phylogeny had preceded the invention of biological nomenclature.
Well, we could just treat taxonomic names as mass nouns....
Mike Keesey--
SERIOUSLY off the anaconda topic (I'm allenph-atsign-unimelb-dot-edu-dot-au if you want to continue off-site), but...
1) Can't find a printed example, but "Whereas most Ecdysozoans have ventral nerve cords, the Chordate has a dorsal nerve cord located above the aorta and digestive tract" sounds like a reasonably idiomatic generic to me... But I guess analogues of Darren's sentence "Anyone who is anyone has heard of the ---" would sound odd to me if you inserted the name of a higher taxon.
2) Ask three Plato-scholars what inspired Plato and you'll get four (or more) opinions, but he did use terms grammatically indistinguishable from distributive singular terms as names for his postulated "forms," so it looks as if the availability of [the distributive singular term] in idiomatic Greek made it easier for him to introduce the theory of forms: made it sound more like "ordinary language." (I wrote the last sentence unselfconsciously, inserted brackets after the fact: D.S.T.s occur in wild-type prose!)
3) Consistency in usage would be nice! One idiom I have noticed in a lot of zoological/paleontological writing that seems strange to my ear is the use of a family name (complete with the apparently plural ending -idae) as a common noun for species of the family: things like "Triceratops is a Maastrichtian ceratopsidae." Is this usage standard among professionals in the field?
Only in Spanish. "Un nuevo Abelisauridae" gives 10 Google hits, "un nuevo Titanosauria" 2â¦
Elsewhere (English, German, French, Russian), you get "Triceratops is a Maastrichtian ceratopsid".
It sounds strange to me, especially because it's inconsistent. "Whereas the Ecdysozoan typically has a ventral nerve chord, the Chordate has a dorsal nerve chord located above the aorta and digestive tract," sounds slightly better but still strange. Not horribly strange, but noticeably.
Interesting thought about Greek and Plato. Did philosophers working in unrelated languages ever come up with a theory of archetypes independently?
Ditto what David said. It sounds really bizarre to me -- where did you come across that?
Sometimes popular science writers use different conventions than academics. One thing I've noted in some (but far from all) popular dinosaur books is a tendency to use the definite article with genera, e.g., "The Archaeopteryx lived in the Late Jurassic." I doubt you would ever find that in a scholarly article, where it would be, "Archaeopteryx lived in the Late Jurassic."
I should say "a recent scholarly article". It might be something that is archaic in academia, but still in mixed usage in popular literature.
no good pics *******
Yes, 19th-century usage. Many monographs on the osteology of a fossil have titles that begin with "On the Structure of the".
Quotations are like policemen-- there's never one at hand when you need one!
Usage of family name (in -idae) as a common noun for species of that family is something I'm sure I've seen repeatedly in journal articles: a recurrent formula in titles of articles describing new species is "a novel X-idae with blah blah." Can't find one at the moment; the general format is like this title (from a 2008 article in, I think, Journal of Veterinary Microbiology): "Identification of a Novel Babesia sp. from a Sable Antelope
(Hippotragus niger Harris, 1838)", but with a plural family name (and no "sp") in place of the genus. I'll let you know if I find an example in the next day or two.
--
Mike-- sorry, I don't know enough about non-european traditions in philosophy to know if theories like Plato's have been formulated elswhere. Nor enough about languages grammatically unlike classical Greek and "Standard Average European" to know if analogues of [the distributive singular term] (o.k., that one was deliberate) are common.
Ah, maybe the veterinarians do it differently.
the image depicting the dark spotted anaconda in this is false, wikipedia claims it was taken at a zoo in italy, and that it was, but who ever took the photo falsey identified it. how hard is it to ask a popular and public zoo if they have an animal?? i've been researching eunectes deschauenseei for several years now, the Punta Verde zoo in italy says they have never had the dark spotted anaconda, and the photo is in fact a yellow anaconda they have had for several years, mark o'shea caught the dark spotted anaconda on his tv show in the late 90's, this was and still is the only photo or video of the snake. you can find the photos easily. www.markoshea.tv season 1 episode 11. 2 photos are shown. animal planet never released the videos of his tv show, claiming too small of an audience, but his show has started back up on discovery HD, still no reruns of the original shows exist, nor can you find them online anywere.