01:119:116 Lecture Notes - Lecture 6: Symmetry In Biology, Triploblasty, Bilateria
25 Jul 2017
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Intro to bilateria: c/c derived traits of bilateria, protostomes, deuterostomes. Lophotrochozoa clade: c/c derived traits, member phyla. Ecdysozoa clade: c/c derived traits, member phyla. True: mesoderm on both sides of cavity (under ectoderm and around digestive system) Pseudo: still have mesoderm under ectoderm but no mesoderm surrounding intestines. = extant animals those existing today. Lack more specific derived traits present in most animals. Not necessarily primitive, just have more ancestral traits. Sponge morphology (for simple sponges others are more complex) Water passes through, food particles get filtered out. Not a digestive cavity, digestion is intracellular (an ancestral trait) Derived trait of eumetazoa extracellular digestion. Cnidocytes specialized stinging cells, unique to cnidaria (in jellyfish, corals) Mostly marine organisms jellyfish (medusozoa), corals (anthozoa) Clade (group anywhere on tree), not phylum (specific level of classification) Named for shared features of some members: Free-living just swimming and floating around. Morphological trait: crown of cilia at anterior end. Coelomates (ancestral trait), 3 main body parts.
