pg - 1 Animals Figure 32.11 Calcarea Silicarea Ctenophora...

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Unformatted text preview: 1 Animals Figure 32.11 Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Molusca Annelida Rotifera Nematoda Arthropoda Radiata Porifera Deuterostomia Lophotrochozoa Ecdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagel ate Two tissue layers, radial symmetry Three tissue layers, Bilateral symmetry Hypothesized phylogeny of animals based on molecular data Outline (phyla in red) Bilateria: Lophotrochozoans Platyhelminthes- the flatworms Lophophorates : Brachiopods , (Phoronids and Ectoprocts) Trochozoans : Molluscs and Annelids Ecdysozoa : Nematodes , Arthropods Deuterostomes : Echinoderms , Chordates Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Molusca Annelida Rotifera Nematoda Arthropoda Radiata Porifera Deuterostomia Lophotrochozoa Ecdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagel ate 2 Bilateria All have bilateral symmetry and triploblastic development Flatworms Members of phylum Platyhelminthes Live in marine, freshwater, and damp terrestrial habitats Are flattened and have a gastrovascular cavity Although placed with the lophotrochozoans They lack either a lophophore or a trochophore larvae Although flatworms undergo triploblastic development they are acoelomates Calcarea Silicarea Ctenophora Cnidaria Echinodermata Chordata Brachiopoda Phoronida Ectoprocta Platyhelminthes Nemertea Molusca Annelida Rotifera Nematoda Arthropoda Radiata Porifera DeuterostomiaLophotrochozoa Ecdysozoa Bilateria Eumetazoa Metazoa Ancestral colonial flagel ate Flatworms are acoelomates Figure 32.8c Body covering (from ectoderm) Tissue- fil ed region (from mesoderm) Digestive tract (from endoderm) Acoelomate. Acoelomates such as flatworms lack a body cavity between the digestive tract and outer body wal . (c) 3 Flatworms are divided into four classes Table 33.2 Turbellarian Turbellarians Are nearly all free-living and mostly marine The best-known turbellarians, commonly called planarians Have light-sensitive eyespots and centralized nerve nets Pharynx. The mouth is at the tip of a muscular pharynx that extends from the animals ventral side. Digestive juices are spil ed onto prey, and the pharynx sucks smal pieces of food into the gastrovascular cavity, where digestion continues. Digestion is completed within the cel s lining the gastro- vascular cavity, which has three branches, each with fine subbranches that pro- vide an extensive surface area. Undigested wastes are egested through the mouth....
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pg - 1 Animals Figure 32.11 Calcarea Silicarea Ctenophora...

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