Do you know what species you have?
78-80 is too high for some species, and yet fine for others (if you don't know the species, I'd suggest lowering it to the mid 70's).
(also, be careful with warmer water tanks and bottom dwelling creatures. The water has less ability to hold oxygen at higher temperatures, and unlike say a catfish or loach, the crayfish doesn't have the ability to just swim up to the top of the tank for a gulp of air if the aeration is poor. Poor aeration can cause either frantic escaping behavior or very sluggish behavior in crayfish.)
Also, remove the shrimp as soon as possible. Crayfish should never be fed other crustaceans of any kind, especially shrimp. Shrimp (commercial and pet) often contain diseases like WSSV which is fatal when contracted by crayfish (contracted through eating the shrimp). If you'd like to feed your crayfish shrimp or other crustaceans, you need to find foods that were processed and freeze-dried or cooked at very high temperatures first to ensure that things like microscopic parasites, WSSV and Aphanomyces astaci (all are fatal when contracted) have been destroyed.
That aside, again, depending on the species. Some crayfish can be skittish around other tankmates. It can even be an individual's personality to be skittish. But ghost shrimp and tetras are very small by comparison to most crayfish, they shouldn't really be a concern for it unless you have a small juvenile.
Perhaps the water change just startled it a bit too much and it's still recovering from the sudden intrusion of of things in it's tank.