How is the structure, function and position of the crayfish nerve cord different from the rat's spinal cord?

In the crayfish's nerve cord, it is the combination of the two nerves that lead from the brain to form the ventral nerve cord which runs down the abdomen. It is important for sending signals from the ganglion to the appendages and muscles. While the rat's spinal cord it runs along the dorsal or back, rather than the front, and it is important for transferring neural signals between the brain and for the rest of the body.