Examples: Tubellarians, Flukes, Tapeworms Soft, flattened worms that have tissues and an internal organ system. Simplest animal to have 3 embryonic germ layers, bilateral symmetry, and cephalization.

Environment Some in aquatic ecosystem Some form parasitic relationships and infect blood or organs of host animal Food Source Carnivores: feed on tiny aquatic animals Scavengers: feed on recently dead animals Parasites: feed on host organism

Maintaining Homeostasis - Internal (Circulation, Respiration, Excretion) No circulatory system rely mostly on diffusion No respiratory organs or heart Have flame cells for removal of wastes Maintaining Homeostasis - External (Response) Ganglia (group of nerve cells control the nervous system)

Movement  Cilia or muscle cells that allow them to twist and turn Reproduction Most are hermaphrodites but must have a partner to reproduce. Some reproduce by fission (splitting in two) Evolutionary Milestone Bilateral Symmetry

Copy this drawing Or Figure 27-3 Page 685  Vocabulary: Coelom (683); Hermaphrodite (686)