This is a good time of year for salamanders, like this zigzag salamander, (Plethodon dorsalis), found at LaRue-Pine Hills Ecological Research Area in Union County, Illinois. Locally common in rocky springs and cave entrances, this salamander is restricted to only a few counties in southern Illinois. Salamanders are in the order Caudata, which comes from the Latin word “caudum” meaning “tail,” and refers to their elongated bodies. Think of the caudal fin of fish, which is the tail fin. There are two main families of salamanders in Illinois. The mole salamanders are in the family Ambystomatidae and the lungless salamanders are in the family Plethodontidae. Salamanders in these families are generically referred to as Ambystomatids and Plethodontids. Ambystomatids have lungs, but lack nasolabial grooves, which is an indented line in the skin from the nostril to the upper lip. Plethodontids have the nasolabial grooves, but lack lungs. Lungless salamanders, like the zigzag salamander, depend on cutaneous respiration which means they breathe through their skin. Moisture aids in gas exchange so remember this when handling salamanders. Bring some water with you to moisten them before returning them to their location undisturbed. There are several hypotheses why these salamanders have evolved the absence of lungs (it’s interesting to note that the common ancestor had lungs). Some suggest that life in a swift, oxygen-rich stream would favor individuals without lungs because the lack of an air-filled sac (the lungs) would prevent salamanders from floating away, and respiration would not be difficult in an environment saturated with oxygen. Others contend that there weren’t fast-flowing Appalachian streams in the late Cretaceous, when this group of salamanders evolved, and that the lack of lungs is due to the reduced size of the mouth (although the reasons for selection of a reduced mouth are not presented). “Plethodon” meany “many teeth” and refers to the long row of teeth found in Plethodontids, while “dorsalis” comes from the Latin term “dorsum” meaning “back” and it refers to the stripe down the back of this species, which is also jagged along the margins, hence the term “zigzag” salamander. The zigzag salamander may be confused with a redback salamander (Plethodon cinereus), but in Illinois they are separated by geographic location.
Posted on: Sat, 15 Mar 2014 05:10:19 +0000
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