Planaria
The Planaria are a primitive form of Platyhelminthes, and can range in size from 1 to 500 millimeters. Most of these animals live underwater and are predators. The Planaria have one of the most advanced nervous systems for all flatworms. This system is centered around the head with a ganglion, and sensory organs that can detect light, somewhat like the human eye but less sophisticated. This sophistication is due to the fact that Planaria are free living and not parasitic unlike most other flatworms. The animal can have anywhere from one to four nerve cords running the length of the body and connected to the ganglion.
The Planaria are a primitive form of Platyhelminthes, and can range in size from 1 to 500 millimeters. Most of these animals live underwater and are predators. The Planaria have one of the most advanced nervous systems for all flatworms. This system is centered around the head with a ganglion, and sensory organs that can detect light, somewhat like the human eye but less sophisticated. This sophistication is due to the fact that Planaria are free living and not parasitic unlike most other flatworms. The animal can have anywhere from one to four nerve cords running the length of the body and connected to the ganglion.