Animals with a larger nerve diameter can better conduct nervous signals throughout the body and thus, possess a faster nerve conduction velocity. The diameter of the nerve indicates the thickness of the myelin sheath, or insulation, around it. The better the insulation, the stronger the nerve signal. In theory, the larger the animal is, the larger its nerve cells. Thus, larger animals would have the fastest nerve conduction velocities.
Myelin, nerve cell insulation that segments a nerve cell into nodes, is the main component in the process of transferring nerve signals. The energy conducted from nerve cell to nerve cell, action potential, jumps over the myelinated area on a neuron as it travels down its axon. The jumping pattern of the action potential from one internode to the next allows it to essentially skip right over the insulated area, which allows for faster action potential conduction. This action potential is then conducted from one synapse, where two nerve cells meet, to the next, traversing the nervous system until it reaches the brain. In neurons, these impulses play a major role in cell-to-cell communication. In muscle cells, the action potentials are an early stepping stone in the process of muscle contraction.