Hiking among Paedomorphic and Neotonic critters—oh my!

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12 July 2015
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Cope's Giant Salamander

Here are a couple of fifty cents words you can impress (or bore) your hiking friends with over your next post-adventure beer. I recently had an encounter with a paedomorphic critter. They are actually quite common in the Cascades and Olympics of Washington. Just what is paedomorphois? It’s a condition (sometimes referred to as neoteny) that several species of salamanders and frogs acquire in which they don’t fully metamorphose (the verb form of metamorphosis-I intend to throw a few fifty-centers at you!) from larvae to adult. But dig this-they mature and are able to reproduce in this aquatic form without becoming terrestrial adults.

One of the most common paedomorphic amphibians in the Olympics is Cope’s giant salamander ( Dicamptodon copei ). In fact, terrestrial fully metamorphosed adults of this species are rare. So you are more apt to see them in their aquatic form complete with gills.

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Beware of the paedomorphic critters that lurk in those waters!

On my recent hike to Sundown Pass, I witnessed one of these critters in the headwaters of the South Fork Skokomish River in a high basin at about 3300 feet. It blended in quite well with the rocky bottom of the clear mountain creek—its preferred habitat. Most of the time they are submerged under rocks during the day—but this one was freely swimming about in broad daylight. If you grew up in the south they look a lot like mudpuppies.

And why do these salamanders remain in their aquatic form? According to the Burke Museum, “This happens because most individuals lack the physiological ability to respond to the hormones that induce metamorphosis in other salamanders.” But occasionally these salamanders do metamorphose, and according to the Burke, “a few (roughly a dozen) terrestrial individuals have been found.” So that would be exciting news to come upon a non-paedomorphic Cope’s giant salamander. And as far as other critters not fully maturing into adults—I have hiked with many!

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