Platyhelminthes
An example of Turbellaria
About Platyhelminthes:
Members are also known as the flat worm. Their name comes from Greek origin, "platy," which translates to "flat," and "helmins," which translates to "worm." They receive oxygen and nutrients through diffusion and their flat shape. The middle layer of these organisms is made up of a spongy mesoderm cells. This phylum is made up of three classes: the Turbellaria, the Trematoda, and the Cestoda. Species such as the tapeworm and the planaria are also members of the Platyhelminthes phylum.
Their Nervous System:
The Platynelminthes Nervous System is simple. They have two brains called ganglion, which is a small bunching of central nerves. They have two nerve cords running down their bodies called ventral nerve cords. They also have two holes, or eyespots, that help sense light. Their nervous system senses it's surroundings and contracts muscles accordingly. The signals sent out by it's nerves are crucial for movement, finding food and escaping predators.