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Unformatted text preview: BIO LECTURE NOTES (2/20/09) • Q: Which animal phyla does NOT have a radial symmetric body plan during some part of its life cycle? o A: Acoelomorpha • Protosome animals • An overview of protostome evolution o Protostomes are bilaterally symmetric, triploblastic, coelomate animals o Protostomes are a monophyletic group comprising two major lineages: Lophotrochozoa (grow by adding on to external skeletons) and Ecdysozoa (go through molds of outershell and grow more) • There are 22 phyla of protostomes • What is a lophotrochozoan? o The 14 phyla of lophotrochozoans include mollusks, annelids, and flatworms o The name lophotrochozoan was inspired by the presence of a feeding structure called a lophophore and a type of larva called a trochophore . Only some phyla have these morphological traits o A lophophore is a specialized structure that rings the mouth of these animals and functions in suspension feeding o Trochophore larva has a ring of cilia around its middle to aid in swimming • Lophotrochozoans have distinctive traits o Lophophores function in suspension feeding in adults (water current carrying food particles goes toward mouth direction) o Trochophore larvae swim and feed • What is an ecdysozoan? o The primary contrast between lophotrochozoans and ecdysozoans involves their methods of growth o Ecdysozoans grow by molting – shedding of the sofe cuticle or hard exoskeleton o The cuticle and exoskeleton serve to protect these animals from predators o The most prominent of the seven ecdysozoan phyla are the roundworms...
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