Tetrapod Zoology

An affection for snapping turtles

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Will and I looked at some really awesome creatures on our recent visit to the Blue Reef Aquarium at Southsea (Portsmouth, UK)… but most of them weren’t tetrapods so I won’t be blogging about them. Sturgeons, wobbegongs, remoras, horseshoe crabs, four-eyed fish, Pacific giant octopus, moray eels. I actually spent ages trying to get a good photo of a wobbegong but couldn’t. Anyway, I had better luck in photographing the Snapping turtle Chelydra serpentina shown here – though it took ages as it wouldn’t keep still. I like my photos for several reasons. The adjacent one, for example, shows the animal doing a very nice neck-stretch – more normally these animals are shown with their necks retracted, making them look rather short-necked.

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Check out the close-up of the head shown here (sorry it’s a bit dark). What’s with those barbel-like structures on the lower jaw? Are they simply there to help disrupt the animal’s outline and aid its camouflage, or do they have a sensory function like the true barbels of fish? I can’t recall reading about them in the snapping turtle literature. The spikes on the back of the skull are also cool. Also emphasized here is how close the eyes are to the snout, and – if you imagine the skull without all the soft tissue in the way – how long and tall the back of the skull is, particularly the sagittal crest.

I’m trying to resist the urge here to talk about the fascinating and dynamic feeding behaviour of these turtles as I covered it all before on ver 1, so if you want to learn more about snappers and how awesome they are what more can I do than recommend my own previous series on them: please see They bite, they grow to huge sizes, they locate human corpses: the snapping turtles, part I, then Snapping turtles, part II: hyperexcitability, supercooling and recolonisation of Europe in the Anthropocene, and finally Snapping turtles, part III: bite, lunge, lure and snap.

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A few things have been published on snappers since I wrote those 2006 articles. De Solla et al. (2007) looked at the concentrations of industrial pollutants in Canadian snapper eggs (there is a reasonable amount of literature on contaminant levels in snapping turtles, for a good review see Christine Bishop’s article here). But most exciting is Anthony Steyermark et al.’s new book, The Biology of the Snapping Turtle (240 pp., John Hopkins University Press), due to appear in Feb’ 2008.

PS – this was sort of meant to be a ‘picture of the day’ piece.

Refs – –

De Solla, S. R., Fernie, K. J., Letcher, R. J., Chu, s. G., Drouillard, K. G. & Shahmiri, S. 2007. Snapping turtles (Chelydra serpentina) as bioindicators in Canadian Areas of Concern in the Great Lakes Basin. 1. Polybrominated diphenyl ethers, polychlorinated biphenyls, and organochlorine pesticides in eggs. Environmental Science and Technology 41, 7252-7259.

Comments

  1. #1 Jason
    January 30, 2008

    You can blog on octopuses. As I learned in church this weekend, they’re just two tetrapods sewn together.

  2. #2 Zach Miller
    January 30, 2008

    Holy crap I need that book! Snappers are my favorite turtles!

    …aren’t they everyone’s?

  3. #3 Sven DiMilo
    January 30, 2008

    Yeah, we’ve all been waiting…and waiting…and waiting for the snapping turtle book. Mike Finkler swears it’s done and coming out soon.
    Let me know when you next make it to the east coast of the USA and we can go out and trap some…they’re far more awesome in a hoop trap and in hand than they are in a tank!

  4. #4 David Marjanovi?
    January 30, 2008

    Certainly more awesome than when your hand is in their beak.

  5. #5 Lars
    January 30, 2008

    Certainly more awesome than when your hand is in their beak…

    Awe-inspiring,rather. I was once seized by the elbow by a medium-sized specimen and it was quite impressive, how much force was exerted and, actually, that it could get my elbow (epicondyle to epicondyle) into its maw.

  6. #6 Sven DiMilo
    January 30, 2008

    p.s. wild ones, of course, are never so nice & clean as that guy in your pics!

  7. #7 Mike Habib
    January 30, 2008

    Snappers are fantastic! My vote for coolest turtle feeding has to go to the matamata, however. I’m still hoping to get a good shot of my mata engulfing a meal, but it takes very good timing and wicked shutter speed…

    Cheers,

    –Mike

  8. #8 Darren Naish
    January 30, 2008

    Mike – have you seen…

    Lemell, P., Lemell, C., Snelderwaard, P., Gumpenberger, M., Wochesländer, R. & Weisgram, J. 2002. Feeding patterns of Chelus fimbriatus (Pleurodira: Chelidae). The Journal of Evolutionary Biology 205, 1495-1506.

    … includes neat high-speed and x-ray photography of engulfing behaviour in matamatas.

    And Sven – do we have a date then? Not sure when I can make it over but I’ll let you know :)

  9. #9 Sven DiMilo
    January 30, 2008

    ‘twould be my pleasure, and I’ll throw in 3 or 4 other species for nothin’

  10. #10 Mike Habib
    January 30, 2008

    Thanks for the citation! I do indeed have that paper, and it is quite good (one note, though: it is in the Journal of Experimental Biology, rather than Ev. Bio). At the same time, I think much more can be learned from that particular feeding dynamic. For one thing, I have noted that the maximum prey size for matas is quite large. My mata can easily take prey slightly longer than his head, and I’ve had zoo animals do the same (not that I do this often, as I expect such meals are larger than would typically be eaten in the wild). The fluid forces involved must therefore be pretty impressive, and calculating the required power would be a lot of fun. The sensory requirements for aim and rapid response might also be of interest.

  11. #11 William Robertson
    January 31, 2008

    That’s a very odd looking snapping turtle. Is it an albino? Every one that I’ve seen has been dark grey. Of course, this one lacks the accumulated algae and sediments that coat most wild specimens, so that might make some difference. But even cleaned museum specimens are much darker than this guy.

  12. #12 Darren Naish
    January 31, 2008

    Oh yeah, J. Exp. Biol, not J. Evol. Biol., how dumb of me. I think matamatas look terrifying – especially the big ones. But that doesn’t mean I don’t love them. Some books say that the name means ‘kill kill kill’, which seems like a mightily odd name to give an animal.

    I agree that the Blue Reef snapper is unusually pale, but it’s not an albino. It looks like it was kept in the dark for years, but its enclosure isn’t particularly poorly lit, and I know nothing of the animal’s life history. Maybe it is just an unusually light-coloured freak.

  13. #13 Nathan Myers
    January 31, 2008

    Let’s not neglect to note that Jason’s remark above is funnier than anything I have posted on TetZoo. The tetrapods in question, by the way, must be the boneless aquatic pterosaurs previously under discussion.

  14. #14 Barn Owl
    January 31, 2008

    During one of our many trips to the upper Texas Coast in my university years, a friend of mine decided to wade across a brackish pond or inlet, while wearing a pair of canvas tennis shoes to protect his feet. The water was deeper than he expected, and he ended up swimming for a short stretch…he swore that something grabbed his shoe, and almost pulled him under the surface briefly. He was sure that the “something” was a large snapping turtle.

    The bayous that criss-crossed the city in which I grew up were not lined with concrete until fairly recently, and it was not uncommon to have turtles and snakes show up in the backyard, especially after heavy rains. One day, our Shetland Sheepdog was barking furiously at something in the passageway on the side of the house, and that something turned out to be a very large Alligator Snapping Turtle. The two Bloodhounds in the yard next door were also going berserk and baying, and the angry turtle was not exactly an easy creature to relocate. I think my dad ended up lifting it into a wheelbarrow, and taking it to the nearest bayou.

  15. #15 Michael Finkler
    June 2, 2010

    Hey, I just discovered this post and I’m happy to say we finally did deliver on the snapping turtle book. You guys have no idea of the crazy, crazy crap we went through with this project, but suffice to say that there were a LOT of extenuating cicumstances that delayed the book for so long. All things considered, I’m rather proud of the book–there is some awesome scholarship in there (esp. the Hutchison’s chapter on fossil chelydrids and Congdon et al.’s chapter on nesting ecology), and although it’s not much of a picture book, I think it will be useful for turtle fans and scholars alike for years to come.

  16. #16 Darren Naish
    June 3, 2010

    Hi Michael – thanks for commenting. I got a copy of the book shortly after its publication; it is indeed an awesome volume, congrats indeed. And, believe me, when it comes to delays on the publication of books – especially multi-authored ones – I can well understand. Everyone interested in turtles should own this book! Get it here.

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