Nematoda
Nematodes (or roundworms) are bilaterally symmetrical, worm-like organisms that are surrounded by a strong, flexible noncellular layer called a cuticle. The cuticle is secreted by cuticle cells and composed of cuticle cells. Near the body but under the epidermal cells are muscle cells that rune the length of the body. Nematodes move by contraction of the longitudinal muscles. Because their internal pressure is high, this causes the body to flex rather than flatten, and the animal moves by thrashing back and forth. No cilia or flagellae are present.
Nematodes have a very simple nervous system consisting of ring of nerve tissue around the pharynx that rises into dorsal and ventral nerve cords running down the length of the whole body. These nerves run along the body under the epidermal cells but above the muscle cells. The pharynx acts as a sort of brain.
Nematodes have a very simple nervous system consisting of ring of nerve tissue around the pharynx that rises into dorsal and ventral nerve cords running down the length of the whole body. These nerves run along the body under the epidermal cells but above the muscle cells. The pharynx acts as a sort of brain.