1. Unit 8 Chapter 26 Sponges, Cnidarians, Flatworms, and Roundworms

2. What is a Sponge? Phylum Porifera (“pore-bearing”) Sponges are aquatic, sessile, asymmetrical invertebrates

3. What is a Sponge? Sponges are filter-feeders Feed by filtering small particles from the water that passes through its pores

4. What is a Sponge? Sponges are soft- bodied and may contain sharp, hard spicules for support & defense Others may contain spongin, a soft, fibrous material

5. What is a Sponge? Hermaphrodites, producing both eggs & sperm A few have external fertilization (occurring outside the animal’s body) Most have internal fertilization (eggs & sperm meet within the animal’s body)

6. What is a Cnidarian? Radially symmetrical, aquatic invertebrates Ex: Jellyfish, coral, hydra, & sea anemones

7. What is a Cnidarian? Cnidarian’s body is only two cell layers Cnidarian’s sting their prey with cells called nematocysts, located on their tentacles

8. What is a Cnidarian? Cnidarian’s have two basic body shapes: Medusa = bell-shaped, free-swimming Polyp = tube-shaped, sessile

9. What is a Cnidarian? Many Cnidarians live in colonies Ex: Portuguese man-of-war Some Cnidarians build reefsEx: Coral

10. What is a Flatworm? Phylum Platyhelminthes Acoelomates, with three cell layers Marine, freshwater, & moist land habitats A Fluke

11. What is a Flatworm? Flatworms may be free-living, like the fresh-water Planarian Planaria have a simple nervous system, including eyespots for light detection

12. What is a Flatworm? Planaria have remarkable powers of regeneration, the ability to replace missing parts

13. What is a Flatworm? Flatworms may be parasitic, like the fluke & tapeworm Tapeworms attach to host’s intestines with their scolex (head) and produce many proglottids (body segments)

14. What is a Flatworm? Tapeworms have a complex life history, that may include several hosts

15. What is a Roundworm? Phylum Nematoda Pseudocoelomates, with two body openings Free-living forms are important decomposers in the soil

16. What is a Roundworm? Many roundworms are parasites, i.e. pinworms, hookworms, & heartworms Trichinosis is a disease caused by a roundworm found in improperly cooked pork Heartworms in a Dog’s heart