power1 - 1 Multicellular animals have certain recognizable...

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1 Multicellular animals have certain recognizable traits • Motility via muscles, nerves • Various internal and external skeletons for protection and locomotory support • Food ingestion and internal digestive system Sensory systems • Sensory systems • Excretion/osmoregulation through skin or internal organs • Gas exchange through skin or internal gills or lungs • Reproduction: sperm and egg produced by meiosis 2 The four major internal organ systems of animals involved with exchange of materials: • Digestive • Circulatory • Respiratory • Excretory 3 Are sponges multicellular animals or elaborate colonies of protists? How do they obtain food? Sponges (Porifera) have a loose organization of cells with no muscles, no nerves 4 How do sessile animals feed themselves? • filter-feeding Choanoflagellates are the nearest relatives of sponges 5 What characterizes a true digestive cavity? • internal secretion of digestive enzymes Cnidarians (sea anemones, corals, hydra, etc.) have a gastro-vascular cavity that serves as a stomach and intestine, but it has only one opening 6 Why are muscles and nerves necessary for animals with true digestive cavities? • to ingest food
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power1 - 1 Multicellular animals have certain recognizable...

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