What's the difference between Red Swamp and White River crawfish?

The two main species of crawfish in Louisiana are Red Swamp crawfish and White River crawfish. Red Swamp crawfish have red pigment in their bodies and have a blue blood vessel under their tails. White River crawfish have no red pigment at all and have no blue blood vessel. When they are boiled, both species turn red; however, the Red Swamp crawfish will be a deeper red.