Both are used to some degree. Mudpuppies rely significantly more upon their limbs for motion when compared to Sirens. Siren limbs are made of cartilage which makes them not quite as efficient for motion when compared to the bony limbs found in mudpuppies. But a Siren's limbs do play a key role as they are used for crossing land when the Siren's chooses to do so.Quick question about salamanders, I noticed a comment about mudpuppies and sirens.
Are the legs in either of these genera vestigial structures, or are they used?