Crawfish

[timmbur22]

Actually, now that I think about it......the color I noticed was not Blue.........it was pure TURQUOISE............

[timmbur22]

It appears they were not molting yet, but forming a blueish exoskeleton underneath their old brown one. They are getting ready to molt. The explanation of bigger crawdads being able to handle colder tempatures makes good sense to me also. Here's a interesting link:

http://www.billwarman.com/crawdad.html