Naturespeak A naturalist's view of the world

September 10, 2007

The Turtle’s Bellybutton

Filed under: Uncategorized — wykes @ 11:18 pm

 I have a nicely bound edition of the American Naturalist of 1872 in my collection, and find it great fun to scan the pages between the marbled end sheets and rich leather binding for gems of wisdom.  On page 305 there is a small notice regarding snapping turtles which I found interesting. Here the editor quotes the great naturalist Agassiz who relates the following in the form of a typical nineteenth century run-on sentence: “The snapping turtle…exhibits it’s small cross like sternum, its long tail, its ferocious habits, even before it leaves the egg, before it breathes through lungs, before it’s derm is ossified to form a bony shield, etc.; nay, it snaps with its gaping jaws at anything brought near (while still in the egg).”  He goes on to reference another naturalist who “quotes as a remarkable fact, that the Chelonara serpentina bites as soon as it is hatched.”

  Though I owe much to such learned folk, I must respectfully disagree with their assessment in this case.  Ladies and gentlemen, I present to you just such a youthful specimen of Chelonia serpentina brought in to me the other day.  Take a look here and you will see a hatchling snapper probably less than a week old. This is not the first, nor shall it be the last, of these little gems that I have encountered over the years. Gentlemen of yesteryear let me assure you – hatchlings snappers don’t bite.

  While I can’t contribute anything to the proposal that these miniature turtles perform the act of biting at shadows while in the egg, I can definitively say they show no desire to do so when newly out of the boundaries of their shell. The whole thing becomes a moot point, when you get down to it, because a new born snapping turtle is so tiny that their jaws would have little effect even if they chose to use them upon our being. Once they gain a few years and a few pounds it’s a different story, but even this is greatly exaggerated.

  Earlier in the year, sometime in late May or early June, this mini turtle was planted as one of 20 -30 round eggs.  The responsible female, who we’ll call “Mom,” chose a site away from the marsh edge to dig a vase shaped hole with her hind feet.  Once her clutch of ping pong balls were deposited, she covered them up and returned to the water -leaving all the incubating duties to the whims of the sun.

  Deep within the nest, the soil temperatures determine which embryos will require pink or blue ribbons upon hatching.  Should any portion of the nest environment hover around 72 -82 degrees F, the eggs in that area will develop into males.  Those eggs which remain cooler or warmer than that range will ultimately turn into females.  Unlike you and I, who are either female or male from the moment of our creation, snapper eggs don’t finish up their genetic wiring until the oven is turned on.

  The new crop of snappers begins hatching out after 60 and 90 days in the cooker. This translates to an emergence time in late August through September.   Unfortunately, most don’t even make it to the hatchling stage because raccoons and opossums destroy the nests.  In some years, it is believed that virtually all of the snapper eggs are destroyed in this manner.

  Our turtle in hand, probably a female by the looks of her (ask me how I know sometime), made it past the pitfalls of development and laboriously dug itself out of the ground into the cruel world above. We can only hope that the rest of her nest mates were equally successful. Oddly enough, in colder climes some snapper young actually chose to overwinter in the nest and wait until the following spring to emerge.  Most of our S.E. Michigan turtles come out in the fall, however.

  At this stage of growth, you’ll see that she is about one inch in diameter – egg sized, in other words.  Her face and upper shell are covered with dried mud and her shell is flexible and leather hard.  While in the egg, her tremendous tail was wrapped once around the body and yolk sac, but now is free to trail on the ground (or flail in the air in this case). Upon hatching, a large yellow yolk sac was still attached to the belly and a tiny white egg tooth (for tearing open the shell) adorned her nose.  Now, a week after hatching, the egg tooth is gone and the sac re-absorbed.  The yolk sac scar is still plainly visible between the plates of her ridiculously small bottom shell (here, look at it again).  Soon the soft spot will disappear under the protection of the bony plates and the turtle’s bellybutton will fade into memory.

 Soon after this picture was taken, the turtling was released to the relative safety of the marsh.  I say “relative” because there are a lot more hungry mouths awaiting such a succulent little snack. Great blue herons, largemouth bass, mink, and even muskrats find the tender little snappers to be valid meal options. She will wisely seek the safety of the mucky bottom and hibernate there through the winter. 

  Hopefully, the next time we see her it will be a few years down the line and she’ll have added a little heft to her frame.  She will, at that point, no longer tolerate our handling and demonstrate in no uncertain terms why she is called a snapping turtle.

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