Naturespeak A naturalist's view of the world

July 27, 2007

Pancake Pig

Filed under: Uncategorized — wykes @ 11:22 pm

    In order to fully understand the Spiny Soft-shelled Turtle, you must change your way of thinking about turtles in general. It has been a few years since I’ve seen one of these remarkable creatures, so was delighted when one was brought in the other day. A Good Samaritan rescued it from the centerline as it was in the risky process of crossing the road. Take a look at this portrait of the wanderer herself, and you’ll agree this is one odd looking beast.

  While it is not unusual to find turtles crossing the road, it is unusual to find a Soft-shell doing it. They rarely leave the water and venture onto land only as far as absolutely necessary in order to lay eggs or bask in the sun.  In both cases they remain within a few energetic paces of the water’s edge.  When startled, they can be incredibly fast at closing the gap to their liquid refuge. Seeing a Soft-shell doing such a sprint will cause you to put aside your notions that all turtles are slow on land.  I believe this individual was on a mission to find a new waterway after its old place dried up. It was a bit chapped. Land travel is risky business for a turtle with sensitive skin and no external shell.

  Most turtles have a solid bony shell which serves as their refuge for head, feet and tail when danger looms. Their shell consists of a layer of bone, directly connected to the ribs, covered with a layer of dry skin plates called scutes. The Soft-shell has relegated its shell to a central disc of bony plates covered over by a thick layer of tough leathery skin. They cannot completely withdraw their body parts.  Take a look at this detail shot of the olive green skin on the top “shell” (carapace) and this shot of the brilliant white underside (plastron). The overall appearance is that of a speckled pancake with the texture akin to leather or vinyl. It is tough and rubbery but susceptible to cuts, scrapes, or tooth punctures.

  To make up for this lack of a protective shell, these turtles pack a vicious wallop in the form of a lightning fast bite. Sharp edged jaws and a long neck combine for a convincing “one-two” defensive move. The particular turtle that I photographed happened to be a gentle soul and allowed herself to be handled, but don’t expect the same from others of her kind. Female Soft-shells are covered with a sparse array of simple spots or blotches on their shells, while males are adorned with open circle spots called ocelli (that’s “o-sell-eye”, a term meaning eye spots).   In their native element, these disc shaped turtles employ their shells for a much more refined purpose that mere protection.  Since they live in sandy or gravelly bottomed lakes and rivers, the shell pattern perfectly blends them into that environment. They habitually settle into the bottom and await prey, in the form of fish or aquatic insects, to drift ignorantly over them.

  Take a look at this view, and you’ll see where the “Spiny” part of the name comes from.  There are a dozen or so bumps or cones projecting from the leading edge of the shell.  I personally wouldn’t call these things spines, but then again I wasn’t around to voice that opinion when these things were named.  There are other kinds of soft-shells that don’t have these bumps, so they do serve as an irritating identifying feature if nothing else.

  Faced with the necessity of spending extended intervals of time lying motionless on the bottom, the soft shell has devised several ways to breathe without giving itself away. Take a look at this detail shot of that wonderful little breathing straw of a snout. These living snorkels can extend their long necks to the surface in order to poke their pig like nose into the air for a quick breath – without moving the rest of the body and blowing their cover.

  The snorkel method only works in very shallow water, so in deeper environs this turtle converts to skin breathing. Like a hybrid vehicle, it converts from atmospheric air via the lungs to water bound oxygen via permeable membranes in the skin. In essence, the skin acts like a giant gill and absorbs oxygen directly from the water.  The thin skin layer of the mouth interior and the lining of the cloaca is especially suited to this kind of respiration.  They move water back and forth in the mouth cavity by means of a hyoid bone which pumps water in and out (this is pretty much what fish do). As long as the animal doesn’t exert too much effort, lung breathing is downright unnecessary.

 Just to clarify things, the cloaca is a nice term for anal opening, so the long and short of it is that the Spiny Soft-shell  breathes through both its front and rear end. Thank God Jacques Cousteau invented the aqua lung, otherwise we humans might have been required to develop a method of anal breathing for our extended underwater dives. We’ll leave that impressive skill to the likes of the pig nose pancake.

1 Comment »

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    Comment by Meemii — May 17, 2010 @ 1:03 am

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