01:119:116 Lecture Notes - Lecture 6: Animal, Trichinosis, Gastrointestinal Tract
28 Feb 2017
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Lecture 6 - unikont diversity 3: basal animals. Lack more specific derived traits present in most animals. We will focus on: porifera & cnidaria. Both of which are basal taxa of major clades. Eumetazoa have tissues & symmetry (usually) radial. Bilateria have symmetry & triploblasty: phylum porifera. Water passes through, food particles filtered out. Not a digestive cavity - digestion is intracellular. Collar cells - feeding cells of sponges. Cnidocytes: specializes stinging cells, unique to cnidaria. Coelom or derivative (most: protostomes, deuterostomes. Clade, not phylum: shared derived traits. Named for shared features of some members: Lophophore (feeding structure) trochophore type of larva. Protostome development (some have deuterstome pattern: phylum platyhelminthes. Parasitic (tapeworm: phylum rotifera, phylum mollusca. Very small - 50 micrometer - 2 millimeter (smaller than protists) Mantle: thin sheet of tissue covering visceral mass. Visceral mass: main body mass, contains viscera (internal organs) Body wall, coelom, many organs divided into segments. Ecdysis: molting - shed external coating during growth.
