BIOL 1030 – TOPIC 12 LECTURE NOTES Topic 12: Introduction to Bilateria, Protostomes, and Lophotrochozoans (Ch. 33) I. Bilateria (clade) A. have bilateral symmetry at some point in their life cycle B. all are triploblastic C. all the rest of the animal phyla that we will cover are in this group D. traditional taxonomy note: 1. were once generally divided into acoelomates, pseudocoelomates, and coelomates 2. acoelomates and pseudocoelomates sometimes called lower bilateria 3. however, based on molecular evidence (sequencing of ribosomal RNA genes) it appears that grouping into acoelomate, pseudocoelomate, and coelomate bilateria produces polyphyletic groups, so…so long old way! 4. even so, the traditional taxonomy is so firmly entrenched that it is worth knowing about E. Most members of Bilateria fall into one of two large clades, Deuterostomia (deuterostomes) and Protostomia (protostomes) F. we will cover one exception to the two main clades: arrow worms II. Phylum Chaetognatha (arrow worms) [clade]
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