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The ventral nerve cords make up the nervous system of some phyla of the invertebrates particularly within the nematodes, annelids and the arthropods. It usually consists of cerebral ganglia anteriorly with the nerve cords running down the ventral ("belly", as opposed to back) plane of the organism. This characteristic is important in qualifying the difference compared to the chordates which have a dorsal nerve cord.

Ventral nerve cords from anterior to posterior (the thoracic and abdominal tagma in the arthropods) are made up of segmented ganglia that are connected by a tract of nerve fibers passing from one side to the other of the nerve cord called commissures[1]. The complete system bears some likeness to a rope ladder. In some animals the bilateral ganglia are fused into a single large ganglion per segment. This characteristic is found mostly in the insects.

The head segment contains the brain, also known as the supraesophageal ganglion. In the insect nervous system, the brain is anatomically divided into the protocerebrum, deutocerebrum, and tritocerebrum. Immediately behind the brain is the subesophageal ganglion, which is composed of three pairs of fused ganglia. It controls the mouthparts, the salivary glands and certain muscles.

Echinoderms have rather complex nervous systems, but lack a true centralized brain. All echinoderms have a network of interlacing nerves called a nerve plexus which lies within as well as below the skin.[16] The esophagus is also surrounded by a number of nerve rings which send radial nerves that are often parallel with the branches of the water vascular system. The ring nerves and radial nerves coordinate the sea star's balance and directional systems. Although the echinoderms do not have many well-defined sensory inputs, they are sensitive to touch, light, temperature, orientation, and the status of water around them.[17] The tube feet, spines, and pedicellariae found on sea stars are sensitive to touch, while eyespots on the ends of the rays are light-sensitive.[18]

Monroe wrote:...And someone please lock week 2's thread.

Cpl Kendall wrote:I voted Ventral, purely because nematodes appear in Spongebob Squarepants.

Monroe wrote:Same here. But the Spongebob logic is hard to argue.

Monroe wrote:oh forgot to say Ventral nerve cords and Echinoderm both allow the possibility of being cut in half (or whatever) and regrown into two identical creatures. That might make people in favor of one of those.

Teaos wrote:Basic creatures are basic, with a species with higher though processes you'd imagin cutting it in half would result in loss of function.

Teaos wrote:Maybe not, its just one might remember people and places and another knows how to do math. Cut someone in the right place and you might actually create a evil twin if one side doesnt have the part of the brain that involves morals.