Both are now recognized as their own species, although it is thought that they evolved into two species when populations of a common ancestral species were separated by glaciers during the last Ice Age. These hybrids are difficult to tell apart from jefferson and blue spotted salamanders, without performing genetic analyses. Blue spotted salamanders are generally blue-black and sprinkled with small blue spots, while Jefferson salamanders tend to be more brown with fewer blue or gray spots on the body. In contrast, both the yellow spotted and marbled salamanders are easy to identify. Spotted salamanders are distinguished by two dorsal rows of big yellow spots.
Marbled salamanders have bands of white, grey, or silver on their backs.
It is here they spend their days foraging for a variety of invertebrates, ranging from earthworms to snails to both larval and adult insects. Most of the year, these stout-bodied animals are quite secretive and are unlikely to be seen unless you are actively searching for them. Fortunately for the naturalist who seeks to observe the habits of these secretive and fascinating creatures, there are certain times during the year when it is possible to observe these animals in high numbers. These migrations occur primarily on rainy nights, and individuals may migrate to woodland pools from as far as 120 m away, and tend to return to the ponds where they were born. Anyone who has not witnessed such a migration will most certainly be amazed by the scale of the phenomenon, which may involve hundreds of salamanders.