I was visiting a guy in the Turtle Mountains recently that had been catching what he thought might be mudpuppies in his minnow traps. He let me see them, and after some bookwork we discovered that they were actually the larval stages of the common tiger salamander. Think of them as the salamander version of a tadpole.
Most everyone is familiar with tiger salamanders. They are amphibians, of course, so they develop from eggs laid in the water, pass through a larval stage during which time they develop lungs, lose their gills, grow legs, and subsequently come on land as adults. We see them mainly in the fall when they leave the water and search for places to hibernate.
The larval stage of a salamander can easily be confused with mudpuppies, which are also amphibians. Think of a mudpuppy as a type of salamander that never quite matures. It develops four legs, but even as an adult still has external gills. The larval stage of salamanders also has external gills, and of course their legs form during larval development. So yes, they can be a little tricky to tell apart.
Mudpuppies are generally an eastern species. They have been documented in North Dakota in the Red River and perhaps Ransom County. Their range in the state is presumably the Red River and perhaps its tributaries. Most people in our region have not seen a mudpuppy.
So how can you tell a mudpuppy from a tiger salamander larva? One of the easiest ways I have found to differentiate them is by looking at the number of digits, or toes, on the front and hind feet. A mudpuppy has four digits on each foot, while the tiger salamander has four digits on the front feet and five on the back feet. Mudpuppies also are lighter in color than the tiger salamander, and lack eyelids.
It is interesting to note that some salamanders never metamorphose into adults. They spend their entire lives in the larval stage. This phenomenon is called neoteny. It is not well understood why this happens, but whatever the reason, these salamanders do become sexually mature.
So the next time you see something in the water that looks like a salamander with gills, count the toes if you can. If you can’t and you are in the Prairie Public listening area, odds are it is a salamander.
Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Dakota College at Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.
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