Protostome Nerves

Caenorhabditis elegans (Wiki) 
"C. elegans is one of the simplest organisms with a nervous system. In the hermaphrodite, this comprises 302 neurons[10] whose pattern of connectivity has been completely mapped out, and shown to be a small-world network.[11] Research has explored the neural mechanisms responsible for several of the more interesting behaviors shown by C. elegans, including chemotaxis, thermotaxis, mechanotransduction, and male mating behavior."