Platyhelminthes
2. The digestive cavity is branched to transport food to all regions of the body.
- Invertebrate
- Simplest animals with bilateral symmetry, an anterior end, three cell layers (ectoderm, endoderm, mesoderm), and cephalization (the concentration of neural and sensory organs at the head region)
- The nervous system consists of a pair of anterior ganglia, usually with two nerve cords winning the length of the organism.
- Can reproduce sexually or asexually and most are monoecious (hermaphrodites).
- Development may be direct (eggs hatch into tiny worms that resemble the adults) or indirect (with a ciliated larval form).
- Have true tissues and organs
- The excretory system consists of flame cells and their associated ducts.
- Digestive cavity has only one opening for both ingestion and egestion so food is unable to be processed continuously.
- Flatworms are acoelomate, which means they have no coelom. They have a solid body with no room for a digestive or respiratory system. This is solved by:
2. The digestive cavity is branched to transport food to all regions of the body.