Chapter 33 PROTOSTOME ANIMALS

Chapter 33 PROTOSTOME ANIMALS - Chapter33PROTOSTOMEANIMALS

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Chapter 33  PROTOSTOME ANIMALS The first bilaterally symmetrical “coelomates” Summary *Why are protostomes important? *General Characteristics *Phylogeny *Fossil record *DNA analysis of rRNA *Diversification *Lophotrochozoans *Ecdysozoans Why Are We Interested in Protostome Animals? *Food source – crustaceans, mollusks *Pollinate crops, enrich soil *Eat crops *Carry diseases, parasites *Very diverse, very abundant *Important in marine and terrestrial ecosystems. General Characteristics *Embryonic development – Protostomic, Triploblasty *Bilateral symmetry *Segmented bodies evolve in 2 groups *Soft-bodied or exoskeletons  of chitin or chitin + CaCO 3 .  i.e. Invertebrates *Coelom     :  ancester had a coelom however, some groups have reduced  or lost   the coelom, others have a pseudocoelom , fig 33.6 Phylogeny - Fossil Record *Trilobites     , extinct animals that existed 450-550 mya.  Segmented bodies, jointed  appendages and a hard exoskeleton. *Arthropods      appeared about 520 mya  *Insects      appeared about 400 mya around the time land plants proliferated. 1
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Phylogeny - DNA *DNA analysis of rRNA produces 2 groups, fig 33.3 *Lophotrochozoa *Ecdysozoa Diversification *Moved from water to land several times.  Challenges were: *Various types of movement evolved *Various eating structures evolved Lophotrochozoa *Named for the feeding structure, lophophore , and larvae, trochophore , in some  of the members, fig 33.4. ***Grow by adding increments to their bodies. *We will look at 4 of the 14 phyla:  Rotifera, Platyhelminthes, Annelida, and  Mollusca. Rotifera *Free-living animals found in soil, marine and fresh water, fig 32.13 Platyhelminthes - flatworms *Parasitic and free-living varieties *3 classes:  Turbellaria, Trematoda and Cestoda, fig 33.13. *Class Tuberllaria
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Chapter 33 PROTOSTOME ANIMALS - Chapter33PROTOSTOMEANIMALS

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