Tuesday, November 16, 2010

Southern Two-lined Salamander

Slender as a whip, a seemingly delicate Southern Two-lined Salamander, Eurycea cirrigera, stares into the maw of my Panasonic. Not long ago, I was with some friends in a large southern Ohio forest, and we found ourselves turning rocks and logs in a quest for salamanders. Every time I engage in such activities, a thought often flashes through my mind: "I am acting like a little kid". So what. I hope I never tire of log-flipping for amphibians.

That day, we didn't find very many salamanders - the rare Mud Salamander, Pseudotriton montanus, was our primary target - but as always, it was nice to run across several fine specimens of the above. Two-lined Salamanders occur most commonly along small streams and rivulets in wooded habitats, and can often be quite abundant.

We have both Southern Two-lined Salamanders and Northern Two-lined Salamanders, Eurycea bislineata, in Ohio. They are essentially identical, differing only in subtle markings and a difference in the number of costal grooves (tiny indents along the lower sides of the animal). Roughly speaking, Northerns occur in the northern half of Ohio, while Southerns occur in the southern half.

While gently prodding the salamander into a new position, I accidentally tugged a bit too hard, and stimulated something that is both horrific and amazing. Two-lined Salamanders are mostly tail, and thus it is this appendage that is most likely to be grabbed by a predator. When I gave it a soft pull, the tail tip broke clean away! The detached tip can be seen in the lower right, while the rest of the animal and the remainder of its tail slinks off in the upper left. As always, you can click on the image to expand it and see more detail.

For several minutes after detaching, the tip of the tail wriggled in rapid, abrupt waves - quite conspicuous. This is a very effective ruse for fooling enemies and allowing the animal a chance to escape. A predator would likely become entranced with dealing with the moving tail tip, permitting the salamander to quickly wriggle out of harm's way and live to reproduce itself.

Within half a day or so of my snapping this fellow's tail off, it would have been well on its way to regenerating a new one. Within a month or so, the tail would have mostly grown back.

Regeneration of body parts is not that rare with simple structures in the animal world, such as this salamander's tail. It doesn't work well with complex organs, such as most mammal appendages. So, should you be threatened by a bear, I'd advise against ripping your arm off and flinging it at the beast, as you won't regrow another.

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2 comments:

Janet Creamer said...

What I would have done to have seen your face at the moment it dropped its tail... :)

Jim McCormac said...

I fainted :-)