What Is Unique about Sponges, Cnidarians, and Flatworms? 1. Indicate ways in which sponges differ from other animals; what characteristics separate the parazoa and eumetazoa lineages? 2. Sponges are sessile. Indicate how this feature influences their basic body plan and feeding style. 3. Indicate the difference between types of sponge based on their "skeleton"; how are bath sponges obtained and prepared for sale? 4. Cnidarians are the simplest animals to have organization at the tissue level. What are the advantages of this level of organization? 5. What characteristics differentiate the two lines of eumetazoan animals and to which line do Cnidarians belong? 6. Describe the following aspects of Cnidarian form and function: basic body plan (both polyp and medusa forms) feeding style (what are nematocysts and how do they work?) digestion (where is the body does it occur?) locomotion in polyp vs. medusa forms (are muscles present?) 7. Name two types of sedentary or sessile cnidarians and indicate how they differ from the hydra. 8. Describe the life style of a typical jellyfish (where does it live, what does it eat?); what is important about box jellies? 9. Be able describe one or two characteristics that separate the following lines within the bilateria: protostomia vs. deuterostomia lophotrochozoa vs. ecdysozoa (see Animals-2 for information on the Ecdysozoa) 10. The flatworms are the simplest animal group to develop mesoderm and cephalization. Indicate the advantages of these features, as illustrated by flatworms. 11. Describe, in general terms, the following aspects of form and function in planarians (free-living flatworms): feeding style digestion locomotion (are muscles present?) 12. Indicate the environments in which planarians can be found (do any live on land?). 13. The majority of flatworm species have become parasitic. Indicate why this may have happened..