Hello there. My approach would be to go to select>color range and select the dark areas. Adjusting the fuzziness and range till I get a good result. That way I can seperate the areas areas I want from the rest of the image.
There is no quick and easy method of handling images such as these. For example, with the sample image shown here Blend If will take you part of the way. The following steps would involve brushwork and Curves. Note that even with this approach as a starting point such elements as the claws will require special additional handlng.
If I'm not too late, for the 4th image on the bottom row I did Image/Auto Tone, then Image/Adjustment/Brightness-Contrast and increased the Brightness with the slider. I then went over some of the artifacts with the Blur Tool at 14%. I did only the last image on the bottom in case it was too late to even help. It was a quick once-over, and I can improve it if there's still time.