Imagine my surprise when I looked in Mr. Pinchy's tank yesterday morning and saw this in his craw cave! It didn't register at first and I thought he was dead. Then I remembered that crawdads molt, and this is the result of shedding the rear portion of his old exoskeleton.
Yesterday evening he in the front of his tank so I could see the process a little better. He is now trying to shed the front portion, including antennae, carapace, and front claws. It looks like it's quite a struggle.
The filmy mass in front of his face is part of the molt.
You can see where the 'film' of the old carapace is coming off.
In the circled area, you can see the new claw slowly coming out of the old one (the red area).
As of this morning, he's still trying to molt the rest of the front part of his exoskeleton. I wish I had a camera that did time lapse photography so I sould see the whole process!
UPDATE: Mr. Pinchy expired a few weeks after an unsuccessful molt. I was told by some crayfish 'experts' that he might have been at the end of his lifespan and too weak to molt properly. I was really sad to see him go, as he was one of the most intersting 'pets' I've ever had!