Flatworms
| Kingdom: | Animalia |
|---|---|
| Subkingdom: | Eumetazoa |
| Clade: | ParaHoxozoa |
| Clade: | Bilateria |
| Clade: | Nephrozoa |
| Unranked: | Protostomia |
| Unranked: | Spiralia |
| Clade: | Rouphozoa |
| Phylum: | Platyhelminthes |
| Source: Integrated Taxonomic Information System | |
| Attribute | Cnidarians and Ctenophores[1] | Platyhelminthes (flatworms)[2][3] | More "advanced" bilaterians[4] |
|---|---|---|---|
| Bilateral symmetry | No | Yes | |
| Number of main cell layers | Two, with jelly-like layer between them (mesoglea) | Three | |
| Distinct brain | No | Yes | |
| Specialized digestive system | No | Yes | |
| Specialized excretory system | No | Yes | |
| Body cavity containing internal organs | No | Yes | |
| Specialized circulatory and respiratory organs | No | Yes | |
- ↑ Cite error: Invalid
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